rcu: Move RCU-related source code to kernel/rcu directory

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 0 insertions, 3396 deletions

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
deleted file mode 100644
index 240604aa3f70..000000000000
--- a/kernel/rcutree.c
+++ /dev/null
@@ -1,3396 +0,0 @@
-/*
- * Read-Copy Update mechanism for mutual exclusion
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
- *
- * Copyright IBM Corporation, 2008
- *
- * Authors: Dipankar Sarma <dipankar@in.ibm.com>
- *	    Manfred Spraul <manfred@colorfullife.com>
- *	    Paul E. McKenney <paulmck@linux.vnet.ibm.com> Hierarchical version
- *
- * Based on the original work by Paul McKenney <paulmck@us.ibm.com>
- * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
- *
- * For detailed explanation of Read-Copy Update mechanism see -
- *	Documentation/RCU
- */
-#include <linux/types.h>
-#include <linux/kernel.h>
-#include <linux/init.h>
-#include <linux/spinlock.h>
-#include <linux/smp.h>
-#include <linux/rcupdate.h>
-#include <linux/interrupt.h>
-#include <linux/sched.h>
-#include <linux/nmi.h>
-#include <linux/atomic.h>
-#include <linux/bitops.h>
-#include <linux/export.h>
-#include <linux/completion.h>
-#include <linux/moduleparam.h>
-#include <linux/percpu.h>
-#include <linux/notifier.h>
-#include <linux/cpu.h>
-#include <linux/mutex.h>
-#include <linux/time.h>
-#include <linux/kernel_stat.h>
-#include <linux/wait.h>
-#include <linux/kthread.h>
-#include <linux/prefetch.h>
-#include <linux/delay.h>
-#include <linux/stop_machine.h>
-#include <linux/random.h>
-#include <linux/ftrace_event.h>
-#include <linux/suspend.h>
-
-#include "rcutree.h"
-#include <trace/events/rcu.h>
-
-#include "rcu.h"
-
-/* Data structures. */
-
-static struct lock_class_key rcu_node_class[RCU_NUM_LVLS];
-static struct lock_class_key rcu_fqs_class[RCU_NUM_LVLS];
-
-/*
- * In order to export the rcu_state name to the tracing tools, it
- * needs to be added in the __tracepoint_string section.
- * This requires defining a separate variable tp_<sname>_varname
- * that points to the string being used, and this will allow
- * the tracing userspace tools to be able to decipher the string
- * address to the matching string.
- */
-#define RCU_STATE_INITIALIZER(sname, sabbr, cr) \
-static char sname##_varname[] = #sname; \
-static const char *tp_##sname##_varname __used __tracepoint_string = sname##_varname; \
-struct rcu_state sname##_state = { \
-	.level = { &sname##_state.node[0] }, \
-	.call = cr, \
-	.fqs_state = RCU_GP_IDLE, \
-	.gpnum = 0UL - 300UL, \
-	.completed = 0UL - 300UL, \
-	.orphan_lock = __RAW_SPIN_LOCK_UNLOCKED(&sname##_state.orphan_lock), \
-	.orphan_nxttail = &sname##_state.orphan_nxtlist, \
-	.orphan_donetail = &sname##_state.orphan_donelist, \
-	.barrier_mutex = __MUTEX_INITIALIZER(sname##_state.barrier_mutex), \
-	.onoff_mutex = __MUTEX_INITIALIZER(sname##_state.onoff_mutex), \
-	.name = sname##_varname, \
-	.abbr = sabbr, \
-}; \
-DEFINE_PER_CPU(struct rcu_data, sname##_data)
-
-RCU_STATE_INITIALIZER(rcu_sched, 's', call_rcu_sched);
-RCU_STATE_INITIALIZER(rcu_bh, 'b', call_rcu_bh);
-
-static struct rcu_state *rcu_state;
-LIST_HEAD(rcu_struct_flavors);
-
-/* Increase (but not decrease) the CONFIG_RCU_FANOUT_LEAF at boot time. */
-static int rcu_fanout_leaf = CONFIG_RCU_FANOUT_LEAF;
-module_param(rcu_fanout_leaf, int, 0444);
-int rcu_num_lvls __read_mostly = RCU_NUM_LVLS;
-static int num_rcu_lvl[] = {  /* Number of rcu_nodes at specified level. */
-	NUM_RCU_LVL_0,
-	NUM_RCU_LVL_1,
-	NUM_RCU_LVL_2,
-	NUM_RCU_LVL_3,
-	NUM_RCU_LVL_4,
-};
-int rcu_num_nodes __read_mostly = NUM_RCU_NODES; /* Total # rcu_nodes in use. */
-
-/*
- * The rcu_scheduler_active variable transitions from zero to one just
- * before the first task is spawned.  So when this variable is zero, RCU
- * can assume that there is but one task, allowing RCU to (for example)
- * optimize synchronize_sched() to a simple barrier().  When this variable
- * is one, RCU must actually do all the hard work required to detect real
- * grace periods.  This variable is also used to suppress boot-time false
- * positives from lockdep-RCU error checking.
- */
-int rcu_scheduler_active __read_mostly;
-EXPORT_SYMBOL_GPL(rcu_scheduler_active);
-
-/*
- * The rcu_scheduler_fully_active variable transitions from zero to one
- * during the early_initcall() processing, which is after the scheduler
- * is capable of creating new tasks.  So RCU processing (for example,
- * creating tasks for RCU priority boosting) must be delayed until after
- * rcu_scheduler_fully_active transitions from zero to one.  We also
- * currently delay invocation of any RCU callbacks until after this point.
- *
- * It might later prove better for people registering RCU callbacks during
- * early boot to take responsibility for these callbacks, but one step at
- * a time.
- */
-static int rcu_scheduler_fully_active __read_mostly;
-
-#ifdef CONFIG_RCU_BOOST
-
-/*
- * Control variables for per-CPU and per-rcu_node kthreads.  These
- * handle all flavors of RCU.
- */
-static DEFINE_PER_CPU(struct task_struct *, rcu_cpu_kthread_task);
-DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
-DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
-DEFINE_PER_CPU(char, rcu_cpu_has_work);
-
-#endif /* #ifdef CONFIG_RCU_BOOST */
-
-static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu);
-static void invoke_rcu_core(void);
-static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp);
-
-/*
- * Track the rcutorture test sequence number and the update version
- * number within a given test.  The rcutorture_testseq is incremented
- * on every rcutorture module load and unload, so has an odd value
- * when a test is running.  The rcutorture_vernum is set to zero
- * when rcutorture starts and is incremented on each rcutorture update.
- * These variables enable correlating rcutorture output with the
- * RCU tracing information.
- */
-unsigned long rcutorture_testseq;
-unsigned long rcutorture_vernum;
-
-/*
- * Return true if an RCU grace period is in progress.  The ACCESS_ONCE()s
- * permit this function to be invoked without holding the root rcu_node
- * structure's ->lock, but of course results can be subject to change.
- */
-static int rcu_gp_in_progress(struct rcu_state *rsp)
-{
-	return ACCESS_ONCE(rsp->completed) != ACCESS_ONCE(rsp->gpnum);
-}
-
-/*
- * Note a quiescent state.  Because we do not need to know
- * how many quiescent states passed, just if there was at least
- * one since the start of the grace period, this just sets a flag.
- * The caller must have disabled preemption.
- */
-void rcu_sched_qs(int cpu)
-{
-	struct rcu_data *rdp = &per_cpu(rcu_sched_data, cpu);
-
-	if (rdp->passed_quiesce == 0)
-		trace_rcu_grace_period(TPS("rcu_sched"), rdp->gpnum, TPS("cpuqs"));
-	rdp->passed_quiesce = 1;
-}
-
-void rcu_bh_qs(int cpu)
-{
-	struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu);
-
-	if (rdp->passed_quiesce == 0)
-		trace_rcu_grace_period(TPS("rcu_bh"), rdp->gpnum, TPS("cpuqs"));
-	rdp->passed_quiesce = 1;
-}
-
-/*
- * Note a context switch.  This is a quiescent state for RCU-sched,
- * and requires special handling for preemptible RCU.
- * The caller must have disabled preemption.
- */
-void rcu_note_context_switch(int cpu)
-{
-	trace_rcu_utilization(TPS("Start context switch"));
-	rcu_sched_qs(cpu);
-	rcu_preempt_note_context_switch(cpu);
-	trace_rcu_utilization(TPS("End context switch"));
-}
-EXPORT_SYMBOL_GPL(rcu_note_context_switch);
-
-static DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
-	.dynticks_nesting = DYNTICK_TASK_EXIT_IDLE,
-	.dynticks = ATOMIC_INIT(1),
-#ifdef CONFIG_NO_HZ_FULL_SYSIDLE
-	.dynticks_idle_nesting = DYNTICK_TASK_NEST_VALUE,
-	.dynticks_idle = ATOMIC_INIT(1),
-#endif /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */
-};
-
-static long blimit = 10;	/* Maximum callbacks per rcu_do_batch. */
-static long qhimark = 10000;	/* If this many pending, ignore blimit. */
-static long qlowmark = 100;	/* Once only this many pending, use blimit. */
-
-module_param(blimit, long, 0444);
-module_param(qhimark, long, 0444);
-module_param(qlowmark, long, 0444);
-
-static ulong jiffies_till_first_fqs = ULONG_MAX;
-static ulong jiffies_till_next_fqs = ULONG_MAX;
-
-module_param(jiffies_till_first_fqs, ulong, 0644);
-module_param(jiffies_till_next_fqs, ulong, 0644);
-
-static void rcu_start_gp_advanced(struct rcu_state *rsp, struct rcu_node *rnp,
-				  struct rcu_data *rdp);
-static void force_qs_rnp(struct rcu_state *rsp,
-			 int (*f)(struct rcu_data *rsp, bool *isidle,
-				  unsigned long *maxj),
-			 bool *isidle, unsigned long *maxj);
-static void force_quiescent_state(struct rcu_state *rsp);
-static int rcu_pending(int cpu);
-
-/*
- * Return the number of RCU-sched batches processed thus far for debug & stats.
- */
-long rcu_batches_completed_sched(void)
-{
-	return rcu_sched_state.completed;
-}
-EXPORT_SYMBOL_GPL(rcu_batches_completed_sched);
-
-/*
- * Return the number of RCU BH batches processed thus far for debug & stats.
- */
-long rcu_batches_completed_bh(void)
-{
-	return rcu_bh_state.completed;
-}
-EXPORT_SYMBOL_GPL(rcu_batches_completed_bh);
-
-/*
- * Force a quiescent state for RCU BH.
- */
-void rcu_bh_force_quiescent_state(void)
-{
-	force_quiescent_state(&rcu_bh_state);
-}
-EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state);
-
-/*
- * Record the number of times rcutorture tests have been initiated and
- * terminated.  This information allows the debugfs tracing stats to be
- * correlated to the rcutorture messages, even when the rcutorture module
- * is being repeatedly loaded and unloaded.  In other words, we cannot
- * store this state in rcutorture itself.
- */
-void rcutorture_record_test_transition(void)
-{
-	rcutorture_testseq++;
-	rcutorture_vernum = 0;
-}
-EXPORT_SYMBOL_GPL(rcutorture_record_test_transition);
-
-/*
- * Record the number of writer passes through the current rcutorture test.
- * This is also used to correlate debugfs tracing stats with the rcutorture
- * messages.
- */
-void rcutorture_record_progress(unsigned long vernum)
-{
-	rcutorture_vernum++;
-}
-EXPORT_SYMBOL_GPL(rcutorture_record_progress);
-
-/*
- * Force a quiescent state for RCU-sched.
- */
-void rcu_sched_force_quiescent_state(void)
-{
-	force_quiescent_state(&rcu_sched_state);
-}
-EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state);
-
-/*
- * Does the CPU have callbacks ready to be invoked?
- */
-static int
-cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp)
-{
-	return &rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL] &&
-	       rdp->nxttail[RCU_DONE_TAIL] != NULL;
-}
-
-/*
- * Does the current CPU require a not-yet-started grace period?
- * The caller must have disabled interrupts to prevent races with
- * normal callback registry.
- */
-static int
-cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp)
-{
-	int i;
-
-	if (rcu_gp_in_progress(rsp))
-		return 0;  /* No, a grace period is already in progress. */
-	if (rcu_nocb_needs_gp(rsp))
-		return 1;  /* Yes, a no-CBs CPU needs one. */
-	if (!rdp->nxttail[RCU_NEXT_TAIL])
-		return 0;  /* No, this is a no-CBs (or offline) CPU. */
-	if (*rdp->nxttail[RCU_NEXT_READY_TAIL])
-		return 1;  /* Yes, this CPU has newly registered callbacks. */
-	for (i = RCU_WAIT_TAIL; i < RCU_NEXT_TAIL; i++)
-		if (rdp->nxttail[i - 1] != rdp->nxttail[i] &&
-		    ULONG_CMP_LT(ACCESS_ONCE(rsp->completed),
-				 rdp->nxtcompleted[i]))
-			return 1;  /* Yes, CBs for future grace period. */
-	return 0; /* No grace period needed. */
-}
-
-/*
- * Return the root node of the specified rcu_state structure.
- */
-static struct rcu_node *rcu_get_root(struct rcu_state *rsp)
-{
-	return &rsp->node[0];
-}
-
-/*
- * rcu_eqs_enter_common - current CPU is moving towards extended quiescent state
- *
- * If the new value of the ->dynticks_nesting counter now is zero,
- * we really have entered idle, and must do the appropriate accounting.
- * The caller must have disabled interrupts.
- */
-static void rcu_eqs_enter_common(struct rcu_dynticks *rdtp, long long oldval,
-				bool user)
-{
-	trace_rcu_dyntick(TPS("Start"), oldval, rdtp->dynticks_nesting);
-	if (!user && !is_idle_task(current)) {
-		struct task_struct *idle __maybe_unused =
-			idle_task(smp_processor_id());
-
-		trace_rcu_dyntick(TPS("Error on entry: not idle task"), oldval, 0);
-		ftrace_dump(DUMP_ORIG);
-		WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
-			  current->pid, current->comm,
-			  idle->pid, idle->comm); /* must be idle task! */
-	}
-	rcu_prepare_for_idle(smp_processor_id());
-	/* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */
-	smp_mb__before_atomic_inc();  /* See above. */
-	atomic_inc(&rdtp->dynticks);
-	smp_mb__after_atomic_inc();  /* Force ordering with next sojourn. */
-	WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1);
-
-	/*
-	 * It is illegal to enter an extended quiescent state while
-	 * in an RCU read-side critical section.
-	 */
-	rcu_lockdep_assert(!lock_is_held(&rcu_lock_map),
-			   "Illegal idle entry in RCU read-side critical section.");
-	rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map),
-			   "Illegal idle entry in RCU-bh read-side critical section.");
-	rcu_lockdep_assert(!lock_is_held(&rcu_sched_lock_map),
-			   "Illegal idle entry in RCU-sched read-side critical section.");
-}
-
-/*
- * Enter an RCU extended quiescent state, which can be either the
- * idle loop or adaptive-tickless usermode execution.
- */
-static void rcu_eqs_enter(bool user)
-{
-	long long oldval;
-	struct rcu_dynticks *rdtp;
-
-	rdtp = this_cpu_ptr(&rcu_dynticks);
-	oldval = rdtp->dynticks_nesting;
-	WARN_ON_ONCE((oldval & DYNTICK_TASK_NEST_MASK) == 0);
-	if ((oldval & DYNTICK_TASK_NEST_MASK) == DYNTICK_TASK_NEST_VALUE)
-		rdtp->dynticks_nesting = 0;
-	else
-		rdtp->dynticks_nesting -= DYNTICK_TASK_NEST_VALUE;
-	rcu_eqs_enter_common(rdtp, oldval, user);
-}
-
-/**
- * rcu_idle_enter - inform RCU that current CPU is entering idle
- *
- * Enter idle mode, in other words, -leave- the mode in which RCU
- * read-side critical sections can occur.  (Though RCU read-side
- * critical sections can occur in irq handlers in idle, a possibility
- * handled by irq_enter() and irq_exit().)
- *
- * We crowbar the ->dynticks_nesting field to zero to allow for
- * the possibility of usermode upcalls having messed up our count
- * of interrupt nesting level during the prior busy period.
- */
-void rcu_idle_enter(void)
-{
-	unsigned long flags;
-
-	local_irq_save(flags);
-	rcu_eqs_enter(false);
-	rcu_sysidle_enter(this_cpu_ptr(&rcu_dynticks), 0);
-	local_irq_restore(flags);
-}
-EXPORT_SYMBOL_GPL(rcu_idle_enter);
-
-#ifdef CONFIG_RCU_USER_QS
-/**
- * rcu_user_enter - inform RCU that we are resuming userspace.
- *
- * Enter RCU idle mode right before resuming userspace.  No use of RCU
- * is permitted between this call and rcu_user_exit(). This way the
- * CPU doesn't need to maintain the tick for RCU maintenance purposes
- * when the CPU runs in userspace.
- */
-void rcu_user_enter(void)
-{
-	rcu_eqs_enter(1);
-}
-#endif /* CONFIG_RCU_USER_QS */
-
-/**
- * rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle
- *
- * Exit from an interrupt handler, which might possibly result in entering
- * idle mode, in other words, leaving the mode in which read-side critical
- * sections can occur.
- *
- * This code assumes that the idle loop never does anything that might
- * result in unbalanced calls to irq_enter() and irq_exit().  If your
- * architecture violates this assumption, RCU will give you what you
- * deserve, good and hard.  But very infrequently and irreproducibly.
- *
- * Use things like work queues to work around this limitation.
- *
- * You have been warned.
- */
-void rcu_irq_exit(void)
-{
-	unsigned long flags;
-	long long oldval;
-	struct rcu_dynticks *rdtp;
-
-	local_irq_save(flags);
-	rdtp = this_cpu_ptr(&rcu_dynticks);
-	oldval = rdtp->dynticks_nesting;
-	rdtp->dynticks_nesting--;
-	WARN_ON_ONCE(rdtp->dynticks_nesting < 0);
-	if (rdtp->dynticks_nesting)
-		trace_rcu_dyntick(TPS("--="), oldval, rdtp->dynticks_nesting);
-	else
-		rcu_eqs_enter_common(rdtp, oldval, true);
-	rcu_sysidle_enter(rdtp, 1);
-	local_irq_restore(flags);
-}
-
-/*
- * rcu_eqs_exit_common - current CPU moving away from extended quiescent state
- *
- * If the new value of the ->dynticks_nesting counter was previously zero,
- * we really have exited idle, and must do the appropriate accounting.
- * The caller must have disabled interrupts.
- */
-static void rcu_eqs_exit_common(struct rcu_dynticks *rdtp, long long oldval,
-			       int user)
-{
-	smp_mb__before_atomic_inc();  /* Force ordering w/previous sojourn. */
-	atomic_inc(&rdtp->dynticks);
-	/* CPUs seeing atomic_inc() must see later RCU read-side crit sects */
-	smp_mb__after_atomic_inc();  /* See above. */
-	WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1));
-	rcu_cleanup_after_idle(smp_processor_id());
-	trace_rcu_dyntick(TPS("End"), oldval, rdtp->dynticks_nesting);
-	if (!user && !is_idle_task(current)) {
-		struct task_struct *idle __maybe_unused =
-			idle_task(smp_processor_id());
-
-		trace_rcu_dyntick(TPS("Error on exit: not idle task"),
-				  oldval, rdtp->dynticks_nesting);
-		ftrace_dump(DUMP_ORIG);
-		WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
-			  current->pid, current->comm,
-			  idle->pid, idle->comm); /* must be idle task! */
-	}
-}
-
-/*
- * Exit an RCU extended quiescent state, which can be either the
- * idle loop or adaptive-tickless usermode execution.
- */
-static void rcu_eqs_exit(bool user)
-{
-	struct rcu_dynticks *rdtp;
-	long long oldval;
-
-	rdtp = this_cpu_ptr(&rcu_dynticks);
-	oldval = rdtp->dynticks_nesting;
-	WARN_ON_ONCE(oldval < 0);
-	if (oldval & DYNTICK_TASK_NEST_MASK)
-		rdtp->dynticks_nesting += DYNTICK_TASK_NEST_VALUE;
-	else
-		rdtp->dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
-	rcu_eqs_exit_common(rdtp, oldval, user);
-}
-
-/**
- * rcu_idle_exit - inform RCU that current CPU is leaving idle
- *
- * Exit idle mode, in other words, -enter- the mode in which RCU
- * read-side critical sections can occur.
- *
- * We crowbar the ->dynticks_nesting field to DYNTICK_TASK_NEST to
- * allow for the possibility of usermode upcalls messing up our count
- * of interrupt nesting level during the busy period that is just
- * now starting.
- */
-void rcu_idle_exit(void)
-{
-	unsigned long flags;
-
-	local_irq_save(flags);
-	rcu_eqs_exit(false);
-	rcu_sysidle_exit(this_cpu_ptr(&rcu_dynticks), 0);
-	local_irq_restore(flags);
-}
-EXPORT_SYMBOL_GPL(rcu_idle_exit);
-
-#ifdef CONFIG_RCU_USER_QS
-/**
- * rcu_user_exit - inform RCU that we are exiting userspace.
- *
- * Exit RCU idle mode while entering the kernel because it can
- * run a RCU read side critical section anytime.
- */
-void rcu_user_exit(void)
-{
-	rcu_eqs_exit(1);
-}
-#endif /* CONFIG_RCU_USER_QS */
-
-/**
- * rcu_irq_enter - inform RCU that current CPU is entering irq away from idle
- *
- * Enter an interrupt handler, which might possibly result in exiting
- * idle mode, in other words, entering the mode in which read-side critical
- * sections can occur.
- *
- * Note that the Linux kernel is fully capable of entering an interrupt
- * handler that it never exits, for example when doing upcalls to
- * user mode!  This code assumes that the idle loop never does upcalls to
- * user mode.  If your architecture does do upcalls from the idle loop (or
- * does anything else that results in unbalanced calls to the irq_enter()
- * and irq_exit() functions), RCU will give you what you deserve, good
- * and hard.  But very infrequently and irreproducibly.
- *
- * Use things like work queues to work around this limitation.
- *
- * You have been warned.
- */
-void rcu_irq_enter(void)
-{
-	unsigned long flags;
-	struct rcu_dynticks *rdtp;
-	long long oldval;
-
-	local_irq_save(flags);
-	rdtp = this_cpu_ptr(&rcu_dynticks);
-	oldval = rdtp->dynticks_nesting;
-	rdtp->dynticks_nesting++;
-	WARN_ON_ONCE(rdtp->dynticks_nesting == 0);
-	if (oldval)
-		trace_rcu_dyntick(TPS("++="), oldval, rdtp->dynticks_nesting);
-	else
-		rcu_eqs_exit_common(rdtp, oldval, true);
-	rcu_sysidle_exit(rdtp, 1);
-	local_irq_restore(flags);
-}
-
-/**
- * rcu_nmi_enter - inform RCU of entry to NMI context
- *
- * If the CPU was idle with dynamic ticks active, and there is no
- * irq handler running, this updates rdtp->dynticks_nmi to let the
- * RCU grace-period handling know that the CPU is active.
- */
-void rcu_nmi_enter(void)
-{
-	struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
-
-	if (rdtp->dynticks_nmi_nesting == 0 &&
-	    (atomic_read(&rdtp->dynticks) & 0x1))
-		return;
-	rdtp->dynticks_nmi_nesting++;
-	smp_mb__before_atomic_inc();  /* Force delay from prior write. */
-	atomic_inc(&rdtp->dynticks);
-	/* CPUs seeing atomic_inc() must see later RCU read-side crit sects */
-	smp_mb__after_atomic_inc();  /* See above. */
-	WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1));
-}
-
-/**
- * rcu_nmi_exit - inform RCU of exit from NMI context
- *
- * If the CPU was idle with dynamic ticks active, and there is no
- * irq handler running, this updates rdtp->dynticks_nmi to let the
- * RCU grace-period handling know that the CPU is no longer active.
- */
-void rcu_nmi_exit(void)
-{
-	struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
-
-	if (rdtp->dynticks_nmi_nesting == 0 ||
-	    --rdtp->dynticks_nmi_nesting != 0)
-		return;
-	/* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */
-	smp_mb__before_atomic_inc();  /* See above. */
-	atomic_inc(&rdtp->dynticks);
-	smp_mb__after_atomic_inc();  /* Force delay to next write. */
-	WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1);
-}
-
-/**
- * __rcu_is_watching - are RCU read-side critical sections safe?
- *
- * Return true if RCU is watching the running CPU, which means that
- * this CPU can safely enter RCU read-side critical sections.  Unlike
- * rcu_is_watching(), the caller of __rcu_is_watching() must have at
- * least disabled preemption.
- */
-bool __rcu_is_watching(void)
-{
-	return atomic_read(this_cpu_ptr(&rcu_dynticks.dynticks)) & 0x1;
-}
-
-/**
- * rcu_is_watching - see if RCU thinks that the current CPU is idle
- *
- * If the current CPU is in its idle loop and is neither in an interrupt
- * or NMI handler, return true.
- */
-bool rcu_is_watching(void)
-{
-	int ret;
-
-	preempt_disable();
-	ret = __rcu_is_watching();
-	preempt_enable();
-	return ret;
-}
-EXPORT_SYMBOL_GPL(rcu_is_watching);
-
-#if defined(CONFIG_PROVE_RCU) && defined(CONFIG_HOTPLUG_CPU)
-
-/*
- * Is the current CPU online?  Disable preemption to avoid false positives
- * that could otherwise happen due to the current CPU number being sampled,
- * this task being preempted, its old CPU being taken offline, resuming
- * on some other CPU, then determining that its old CPU is now offline.
- * It is OK to use RCU on an offline processor during initial boot, hence
- * the check for rcu_scheduler_fully_active.  Note also that it is OK
- * for a CPU coming online to use RCU for one jiffy prior to marking itself
- * online in the cpu_online_mask.  Similarly, it is OK for a CPU going
- * offline to continue to use RCU for one jiffy after marking itself
- * offline in the cpu_online_mask.  This leniency is necessary given the
- * non-atomic nature of the online and offline processing, for example,
- * the fact that a CPU enters the scheduler after completing the CPU_DYING
- * notifiers.
- *
- * This is also why RCU internally marks CPUs online during the
- * CPU_UP_PREPARE phase and offline during the CPU_DEAD phase.
- *
- * Disable checking if in an NMI handler because we cannot safely report
- * errors from NMI handlers anyway.
- */
-bool rcu_lockdep_current_cpu_online(void)
-{
-	struct rcu_data *rdp;
-	struct rcu_node *rnp;
-	bool ret;
-
-	if (in_nmi())
-		return 1;
-	preempt_disable();
-	rdp = this_cpu_ptr(&rcu_sched_data);
-	rnp = rdp->mynode;
-	ret = (rdp->grpmask & rnp->qsmaskinit) ||
-	      !rcu_scheduler_fully_active;
-	preempt_enable();
-	return ret;
-}
-EXPORT_SYMBOL_GPL(rcu_lockdep_current_cpu_online);
-
-#endif /* #if defined(CONFIG_PROVE_RCU) && defined(CONFIG_HOTPLUG_CPU) */
-
-/**
- * rcu_is_cpu_rrupt_from_idle - see if idle or immediately interrupted from idle
- *
- * If the current CPU is idle or running at a first-level (not nested)
- * interrupt from idle, return true.  The caller must have at least
- * disabled preemption.
- */
-static int rcu_is_cpu_rrupt_from_idle(void)
-{
-	return __this_cpu_read(rcu_dynticks.dynticks_nesting) <= 1;
-}
-
-/*
- * Snapshot the specified CPU's dynticks counter so that we can later
- * credit them with an implicit quiescent state.  Return 1 if this CPU
- * is in dynticks idle mode, which is an extended quiescent state.
- */
-static int dyntick_save_progress_counter(struct rcu_data *rdp,
-					 bool *isidle, unsigned long *maxj)
-{
-	rdp->dynticks_snap = atomic_add_return(0, &rdp->dynticks->dynticks);
-	rcu_sysidle_check_cpu(rdp, isidle, maxj);
-	return (rdp->dynticks_snap & 0x1) == 0;
-}
-
-/*
- * Return true if the specified CPU has passed through a quiescent
- * state by virtue of being in or having passed through an dynticks
- * idle state since the last call to dyntick_save_progress_counter()
- * for this same CPU, or by virtue of having been offline.
- */
-static int rcu_implicit_dynticks_qs(struct rcu_data *rdp,
-				    bool *isidle, unsigned long *maxj)
-{
-	unsigned int curr;
-	unsigned int snap;
-
-	curr = (unsigned int)atomic_add_return(0, &rdp->dynticks->dynticks);
-	snap = (unsigned int)rdp->dynticks_snap;
-
-	/*
-	 * If the CPU passed through or entered a dynticks idle phase with
-	 * no active irq/NMI handlers, then we can safely pretend that the CPU
-	 * already acknowledged the request to pass through a quiescent
-	 * state.  Either way, that CPU cannot possibly be in an RCU
-	 * read-side critical section that started before the beginning
-	 * of the current RCU grace period.
-	 */
-	if ((curr & 0x1) == 0 || UINT_CMP_GE(curr, snap + 2)) {
-		trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("dti"));
-		rdp->dynticks_fqs++;
-		return 1;
-	}
-
-	/*
-	 * Check for the CPU being offline, but only if the grace period
-	 * is old enough.  We don't need to worry about the CPU changing
-	 * state: If we see it offline even once, it has been through a
-	 * quiescent state.
-	 *
-	 * The reason for insisting that the grace period be at least
-	 * one jiffy old is that CPUs that are not quite online and that
-	 * have just gone offline can still execute RCU read-side critical
-	 * sections.
-	 */
-	if (ULONG_CMP_GE(rdp->rsp->gp_start + 2, jiffies))
-		return 0;  /* Grace period is not old enough. */
-	barrier();
-	if (cpu_is_offline(rdp->cpu)) {
-		trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("ofl"));
-		rdp->offline_fqs++;
-		return 1;
-	}
-
-	/*
-	 * There is a possibility that a CPU in adaptive-ticks state
-	 * might run in the kernel with the scheduling-clock tick disabled
-	 * for an extended time period.  Invoke rcu_kick_nohz_cpu() to
-	 * force the CPU to restart the scheduling-clock tick in this
-	 * CPU is in this state.
-	 */
-	rcu_kick_nohz_cpu(rdp->cpu);
-
-	return 0;
-}
-
-static void record_gp_stall_check_time(struct rcu_state *rsp)
-{
-	unsigned long j = ACCESS_ONCE(jiffies);
-
-	rsp->gp_start = j;
-	smp_wmb(); /* Record start time before stall time. */
-	rsp->jiffies_stall = j + rcu_jiffies_till_stall_check();
-}
-
-/*
- * Dump stacks of all tasks running on stalled CPUs.  This is a fallback
- * for architectures that do not implement trigger_all_cpu_backtrace().
- * The NMI-triggered stack traces are more accurate because they are
- * printed by the target CPU.
- */
-static void rcu_dump_cpu_stacks(struct rcu_state *rsp)
-{
-	int cpu;
-	unsigned long flags;
-	struct rcu_node *rnp;
-
-	rcu_for_each_leaf_node(rsp, rnp) {
-		raw_spin_lock_irqsave(&rnp->lock, flags);
-		if (rnp->qsmask != 0) {
-			for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++)
-				if (rnp->qsmask & (1UL << cpu))
-					dump_cpu_task(rnp->grplo + cpu);
-		}
-		raw_spin_unlock_irqrestore(&rnp->lock, flags);
-	}
-}
-
-static void print_other_cpu_stall(struct rcu_state *rsp)
-{
-	int cpu;
-	long delta;
-	unsigned long flags;
-	int ndetected = 0;
-	struct rcu_node *rnp = rcu_get_root(rsp);
-	long totqlen = 0;
-
-	/* Only let one CPU complain about others per time interval. */
-
-	raw_spin_lock_irqsave(&rnp->lock, flags);
-	delta = jiffies - rsp->jiffies_stall;
-	if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) {
-		raw_spin_unlock_irqrestore(&rnp->lock, flags);
-		return;
-	}
-	rsp->jiffies_stall = jiffies + 3 * rcu_jiffies_till_stall_check() + 3;
-	raw_spin_unlock_irqrestore(&rnp->lock, flags);
-
-	/*
-	 * OK, time to rat on our buddy...
-	 * See Documentation/RCU/stallwarn.txt for info on how to debug
-	 * RCU CPU stall warnings.
-	 */
-	pr_err("INFO: %s detected stalls on CPUs/tasks:",
-	       rsp->name);
-	print_cpu_stall_info_begin();
-	rcu_for_each_leaf_node(rsp, rnp) {
-		raw_spin_lock_irqsave(&rnp->lock, flags);
-		ndetected += rcu_print_task_stall(rnp);
-		if (rnp->qsmask != 0) {
-			for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++)
-				if (rnp->qsmask & (1UL << cpu)) {
-					print_cpu_stall_info(rsp,
-							     rnp->grplo + cpu);
-					ndetected++;
-				}
-		}
-		raw_spin_unlock_irqrestore(&rnp->lock, flags);
-	}
-
-	/*
-	 * Now rat on any tasks that got kicked up to the root rcu_node
-	 * due to CPU offlining.
-	 */
-	rnp = rcu_get_root(rsp);
-	raw_spin_lock_irqsave(&rnp->lock, flags);
-	ndetected += rcu_print_task_stall(rnp);
-	raw_spin_unlock_irqrestore(&rnp->lock, flags);
-
-	print_cpu_stall_info_end();
-	for_each_possible_cpu(cpu)
-		totqlen += per_cpu_ptr(rsp->rda, cpu)->qlen;
-	pr_cont("(detected by %d, t=%ld jiffies, g=%lu, c=%lu, q=%lu)\n",
-	       smp_processor_id(), (long)(jiffies - rsp->gp_start),
-	       rsp->gpnum, rsp->completed, totqlen);
-	if (ndetected == 0)
-		pr_err("INFO: Stall ended before state dump start\n");
-	else if (!trigger_all_cpu_backtrace())
-		rcu_dump_cpu_stacks(rsp);
-
-	/* Complain about tasks blocking the grace period. */
-
-	rcu_print_detail_task_stall(rsp);
-
-	force_quiescent_state(rsp);  /* Kick them all. */
-}
-
-static void print_cpu_stall(struct rcu_state *rsp)
-{
-	int cpu;
-	unsigned long flags;
-	struct rcu_node *rnp = rcu_get_root(rsp);
-	long totqlen = 0;
-
-	/*
-	 * OK, time to rat on ourselves...
-	 * See Documentation/RCU/stallwarn.txt for info on how to debug
-	 * RCU CPU stall warnings.
-	 */
-	pr_err("INFO: %s self-detected stall on CPU", rsp->name);
-	print_cpu_stall_info_begin();
-	print_cpu_stall_info(rsp, smp_processor_id());
-	print_cpu_stall_info_end();
-	for_each_possible_cpu(cpu)
-		totqlen += per_cpu_ptr(rsp->rda, cpu)->qlen;
-	pr_cont(" (t=%lu jiffies g=%lu c=%lu q=%lu)\n",
-		jiffies - rsp->gp_start, rsp->gpnum, rsp->completed, totqlen);
-	if (!trigger_all_cpu_backtrace())
-		dump_stack();
-
-	raw_spin_lock_irqsave(&rnp->lock, flags);
-	if (ULONG_CMP_GE(jiffies, rsp->jiffies_stall))
-		rsp->jiffies_stall = jiffies +
-				     3 * rcu_jiffies_till_stall_check() + 3;
-	raw_spin_unlock_irqrestore(&rnp->lock, flags);
-
-	set_need_resched();  /* kick ourselves to get things going. */
-}
-
-static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
-{
-	unsigned long completed;
-	unsigned long gpnum;
-	unsigned long gps;
-	unsigned long j;
-	unsigned long js;
-	struct rcu_node *rnp;
-
-	if (rcu_cpu_stall_suppress || !rcu_gp_in_progress(rsp))
-		return;
-	j = ACCESS_ONCE(jiffies);
-
-	/*
-	 * Lots of memory barriers to reject false positives.
-	 *
-	 * The idea is to pick up rsp->gpnum, then rsp->jiffies_stall,
-	 * then rsp->gp_start, and finally rsp->completed.  These values
-	 * are updated in the opposite order with memory barriers (or
-	 * equivalent) during grace-period initialization and cleanup.
-	 * Now, a false positive can occur if we get an new value of
-	 * rsp->gp_start and a old value of rsp->jiffies_stall.  But given
-	 * the memory barriers, the only way that this can happen is if one
-	 * grace period ends and another starts between these two fetches.
-	 * Detect this by comparing rsp->completed with the previous fetch
-	 * from rsp->gpnum.
-	 *
-	 * Given this check, comparisons of jiffies, rsp->jiffies_stall,
-	 * and rsp->gp_start suffice to forestall false positives.
-	 */
-	gpnum = ACCESS_ONCE(rsp->gpnum);
-	smp_rmb(); /* Pick up ->gpnum first... */
-	js = ACCESS_ONCE(rsp->jiffies_stall);
-	smp_rmb(); /* ...then ->jiffies_stall before the rest... */
-	gps = ACCESS_ONCE(rsp->gp_start);
-	smp_rmb(); /* ...and finally ->gp_start before ->completed. */
-	completed = ACCESS_ONCE(rsp->completed);
-	if (ULONG_CMP_GE(completed, gpnum) ||
-	    ULONG_CMP_LT(j, js) ||
-	    ULONG_CMP_GE(gps, js))
-		return; /* No stall or GP completed since entering function. */
-	rnp = rdp->mynode;
-	if (rcu_gp_in_progress(rsp) &&
-	    (ACCESS_ONCE(rnp->qsmask) & rdp->grpmask)) {
-
-		/* We haven't checked in, so go dump stack. */
-		print_cpu_stall(rsp);
-
-	} else if (rcu_gp_in_progress(rsp) &&
-		   ULONG_CMP_GE(j, js + RCU_STALL_RAT_DELAY)) {
-
-		/* They had a few time units to dump stack, so complain. */
-		print_other_cpu_stall(rsp);
-	}
-}
-
-/**
- * rcu_cpu_stall_reset - prevent further stall warnings in current grace period
- *
- * Set the stall-warning timeout way off into the future, thus preventing
- * any RCU CPU stall-warning messages from appearing in the current set of
- * RCU grace periods.
- *
- * The caller must disable hard irqs.
- */
-void rcu_cpu_stall_reset(void)
-{
-	struct rcu_state *rsp;
-
-	for_each_rcu_flavor(rsp)
-		rsp->jiffies_stall = jiffies + ULONG_MAX / 2;
-}
-
-/*
- * Initialize the specified rcu_data structure's callback list to empty.
- */
-static void init_callback_list(struct rcu_data *rdp)
-{
-	int i;
-
-	if (init_nocb_callback_list(rdp))
-		return;
-	rdp->nxtlist = NULL;
-	for (i = 0; i < RCU_NEXT_SIZE; i++)
-		rdp->nxttail[i] = &rdp->nxtlist;
-}
-
-/*
- * Determine the value that ->completed will have at the end of the
- * next subsequent grace period.  This is used to tag callbacks so that
- * a CPU can invoke callbacks in a timely fashion even if that CPU has
- * been dyntick-idle for an extended period with callbacks under the
- * influence of RCU_FAST_NO_HZ.
- *
- * The caller must hold rnp->lock with interrupts disabled.
- */
-static unsigned long rcu_cbs_completed(struct rcu_state *rsp,
-				       struct rcu_node *rnp)
-{
-	/*
-	 * If RCU is idle, we just wait for the next grace period.
-	 * But we can only be sure that RCU is idle if we are looking
-	 * at the root rcu_node structure -- otherwise, a new grace
-	 * period might have started, but just not yet gotten around
-	 * to initializing the current non-root rcu_node structure.
-	 */
-	if (rcu_get_root(rsp) == rnp && rnp->gpnum == rnp->completed)
-		return rnp->completed + 1;
-
-	/*
-	 * Otherwise, wait for a possible partial grace period and
-	 * then the subsequent full grace period.
-	 */
-	return rnp->completed + 2;
-}
-
-/*
- * Trace-event helper function for rcu_start_future_gp() and
- * rcu_nocb_wait_gp().
- */
-static void trace_rcu_future_gp(struct rcu_node *rnp, struct rcu_data *rdp,
-				unsigned long c, const char *s)
-{
-	trace_rcu_future_grace_period(rdp->rsp->name, rnp->gpnum,
-				      rnp->completed, c, rnp->level,
-				      rnp->grplo, rnp->grphi, s);
-}
-
-/*
- * Start some future grace period, as needed to handle newly arrived
- * callbacks.  The required future grace periods are recorded in each
- * rcu_node structure's ->need_future_gp field.
- *
- * The caller must hold the specified rcu_node structure's ->lock.
- */
-static unsigned long __maybe_unused
-rcu_start_future_gp(struct rcu_node *rnp, struct rcu_data *rdp)
-{
-	unsigned long c;
-	int i;
-	struct rcu_node *rnp_root = rcu_get_root(rdp->rsp);
-
-	/*
-	 * Pick up grace-period number for new callbacks.  If this
-	 * grace period is already marked as needed, return to the caller.
-	 */
-	c = rcu_cbs_completed(rdp->rsp, rnp);
-	trace_rcu_future_gp(rnp, rdp, c, TPS("Startleaf"));
-	if (rnp->need_future_gp[c & 0x1]) {
-		trace_rcu_future_gp(rnp, rdp, c, TPS("Prestartleaf"));
-		return c;
-	}
-
-	/*
-	 * If either this rcu_node structure or the root rcu_node structure
-	 * believe that a grace period is in progress, then we must wait
-	 * for the one following, which is in "c".  Because our request
-	 * will be noticed at the end of the current grace period, we don't
-	 * need to explicitly start one.
-	 */
-	if (rnp->gpnum != rnp->completed ||
-	    ACCESS_ONCE(rnp->gpnum) != ACCESS_ONCE(rnp->completed)) {
-		rnp->need_future_gp[c & 0x1]++;
-		trace_rcu_future_gp(rnp, rdp, c, TPS("Startedleaf"));
-		return c;
-	}
-
-	/*
-	 * There might be no grace period in progress.  If we don't already
-	 * hold it, acquire the root rcu_node structure's lock in order to
-	 * start one (if needed).
-	 */
-	if (rnp != rnp_root)
-		raw_spin_lock(&rnp_root->lock);
-
-	/*
-	 * Get a new grace-period number.  If there really is no grace
-	 * period in progress, it will be smaller than the one we obtained
-	 * earlier.  Adjust callbacks as needed.  Note that even no-CBs
-	 * CPUs have a ->nxtcompleted[] array, so no no-CBs checks needed.
-	 */
-	c = rcu_cbs_completed(rdp->rsp, rnp_root);
-	for (i = RCU_DONE_TAIL; i < RCU_NEXT_TAIL; i++)
-		if (ULONG_CMP_LT(c, rdp->nxtcompleted[i]))
-			rdp->nxtcompleted[i] = c;
-
-	/*
-	 * If the needed for the required grace period is already
-	 * recorded, trace and leave.
-	 */
-	if (rnp_root->need_future_gp[c & 0x1]) {
-		trace_rcu_future_gp(rnp, rdp, c, TPS("Prestartedroot"));
-		goto unlock_out;
-	}
-
-	/* Record the need for the future grace period. */
-	rnp_root->need_future_gp[c & 0x1]++;
-
-	/* If a grace period is not already in progress, start one. */
-	if (rnp_root->gpnum != rnp_root->completed) {
-		trace_rcu_future_gp(rnp, rdp, c, TPS("Startedleafroot"));
-	} else {
-		trace_rcu_future_gp(rnp, rdp, c, TPS("Startedroot"));
-		rcu_start_gp_advanced(rdp->rsp, rnp_root, rdp);
-	}
-unlock_out:
-	if (rnp != rnp_root)
-		raw_spin_unlock(&rnp_root->lock);
-	return c;
-}
-
-/*
- * Clean up any old requests for the just-ended grace period.  Also return
- * whether any additional grace periods have been requested.  Also invoke
- * rcu_nocb_gp_cleanup() in order to wake up any no-callbacks kthreads
- * waiting for this grace period to complete.
- */
-static int rcu_future_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp)
-{
-	int c = rnp->completed;
-	int needmore;
-	struct rcu_data *rdp = this_cpu_ptr(rsp->rda);
-
-	rcu_nocb_gp_cleanup(rsp, rnp);
-	rnp->need_future_gp[c & 0x1] = 0;
-	needmore = rnp->need_future_gp[(c + 1) & 0x1];
-	trace_rcu_future_gp(rnp, rdp, c,
-			    needmore ? TPS("CleanupMore") : TPS("Cleanup"));
-	return needmore;
-}
-
-/*
- * If there is room, assign a ->completed number to any callbacks on
- * this CPU that have not already been assigned.  Also accelerate any
- * callbacks that were previously assigned a ->completed number that has
- * since proven to be too conservative, which can happen if callbacks get
- * assigned a ->completed number while RCU is idle, but with reference to
- * a non-root rcu_node structure.  This function is idempotent, so it does
- * not hurt to call it repeatedly.
- *
- * The caller must hold rnp->lock with interrupts disabled.
- */
-static void rcu_accelerate_cbs(struct rcu_state *rsp, struct rcu_node *rnp,
-			       struct rcu_data *rdp)
-{
-	unsigned long c;
-	int i;
-
-	/* If the CPU has no callbacks, nothing to do. */
-	if (!rdp->nxttail[RCU_NEXT_TAIL] || !*rdp->nxttail[RCU_DONE_TAIL])
-		return;
-
-	/*
-	 * Starting from the sublist containing the callbacks most
-	 * recently assigned a ->completed number and working down, find the
-	 * first sublist that is not assignable to an upcoming grace period.
-	 * Such a sublist has something in it (first two tests) and has
-	 * a ->completed number assigned that will complete sooner than
-	 * the ->completed number for newly arrived callbacks (last test).
-	 *
-	 * The key point is that any later sublist can be assigned the
-	 * same ->completed number as the newly arrived callbacks, which
-	 * means that the callbacks in any of these later sublist can be
-	 * grouped into a single sublist, whether or not they have already
-	 * been assigned a ->completed number.
-	 */
-	c = rcu_cbs_completed(rsp, rnp);
-	for (i = RCU_NEXT_TAIL - 1; i > RCU_DONE_TAIL; i--)
-		if (rdp->nxttail[i] != rdp->nxttail[i - 1] &&
-		    !ULONG_CMP_GE(rdp->nxtcompleted[i], c))
-			break;
-
-	/*
-	 * If there are no sublist for unassigned callbacks, leave.
-	 * At the same time, advance "i" one sublist, so that "i" will
-	 * index into the sublist where all the remaining callbacks should
-	 * be grouped into.
-	 */
-	if (++i >= RCU_NEXT_TAIL)
-		return;
-
-	/*
-	 * Assign all subsequent callbacks' ->completed number to the next
-	 * full grace period and group them all in the sublist initially
-	 * indexed by "i".
-	 */
-	for (; i <= RCU_NEXT_TAIL; i++) {
-		rdp->nxttail[i] = rdp->nxttail[RCU_NEXT_TAIL];
-		rdp->nxtcompleted[i] = c;
-	}
-	/* Record any needed additional grace periods. */
-	rcu_start_future_gp(rnp, rdp);
-
-	/* Trace depending on how much we were able to accelerate. */
-	if (!*rdp->nxttail[RCU_WAIT_TAIL])
-		trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("AccWaitCB"));
-	else
-		trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("AccReadyCB"));
-}
-
-/*
- * Move any callbacks whose grace period has completed to the
- * RCU_DONE_TAIL sublist, then compact the remaining sublists and
- * assign ->completed numbers to any callbacks in the RCU_NEXT_TAIL
- * sublist.  This function is idempotent, so it does not hurt to
- * invoke it repeatedly.  As long as it is not invoked -too- often...
- *
- * The caller must hold rnp->lock with interrupts disabled.
- */
-static void rcu_advance_cbs(struct rcu_state *rsp, struct rcu_node *rnp,
-			    struct rcu_data *rdp)
-{
-	int i, j;
-
-	/* If the CPU has no callbacks, nothing to do. */
-	if (!rdp->nxttail[RCU_NEXT_TAIL] || !*rdp->nxttail[RCU_DONE_TAIL])
-		return;
-
-	/*
-	 * Find all callbacks whose ->completed numbers indicate that they
-	 * are ready to invoke, and put them into the RCU_DONE_TAIL sublist.
-	 */
-	for (i = RCU_WAIT_TAIL; i < RCU_NEXT_TAIL; i++) {
-		if (ULONG_CMP_LT(rnp->completed, rdp->nxtcompleted[i]))
-			break;
-		rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[i];
-	}
-	/* Clean up any sublist tail pointers that were misordered above. */
-	for (j = RCU_WAIT_TAIL; j < i; j++)
-		rdp->nxttail[j] = rdp->nxttail[RCU_DONE_TAIL];
-
-	/* Copy down callbacks to fill in empty sublists. */
-	for (j = RCU_WAIT_TAIL; i < RCU_NEXT_TAIL; i++, j++) {
-		if (rdp->nxttail[j] == rdp->nxttail[RCU_NEXT_TAIL])
-			break;
-		rdp->nxttail[j] = rdp->nxttail[i];
-		rdp->nxtcompleted[j] = rdp->nxtcompleted[i];
-	}
-
-	/* Classify any remaining callbacks. */
-	rcu_accelerate_cbs(rsp, rnp, rdp);
-}
-
-/*
- * Update CPU-local rcu_data state to record the beginnings and ends of
- * grace periods.  The caller must hold the ->lock of the leaf rcu_node
- * structure corresponding to the current CPU, and must have irqs disabled.
- */
-static void __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp)
-{
-	/* Handle the ends of any preceding grace periods first. */
-	if (rdp->completed == rnp->completed) {
-
-		/* No grace period end, so just accelerate recent callbacks. */
-		rcu_accelerate_cbs(rsp, rnp, rdp);
-
-	} else {
-
-		/* Advance callbacks. */
-		rcu_advance_cbs(rsp, rnp, rdp);
-
-		/* Remember that we saw this grace-period completion. */
-		rdp->completed = rnp->completed;
-		trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpuend"));
-	}
-
-	if (rdp->gpnum != rnp->gpnum) {
-		/*
-		 * If the current grace period is waiting for this CPU,
-		 * set up to detect a quiescent state, otherwise don't
-		 * go looking for one.
-		 */
-		rdp->gpnum = rnp->gpnum;
-		trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpustart"));
-		rdp->passed_quiesce = 0;
-		rdp->qs_pending = !!(rnp->qsmask & rdp->grpmask);
-		zero_cpu_stall_ticks(rdp);
-	}
-}
-
-static void note_gp_changes(struct rcu_state *rsp, struct rcu_data *rdp)
-{
-	unsigned long flags;
-	struct rcu_node *rnp;
-
-	local_irq_save(flags);
-	rnp = rdp->mynode;
-	if ((rdp->gpnum == ACCESS_ONCE(rnp->gpnum) &&
-	     rdp->completed == ACCESS_ONCE(rnp->completed)) || /* w/out lock. */
-	    !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */
-		local_irq_restore(flags);
-		return;
-	}
-	__note_gp_changes(rsp, rnp, rdp);
-	raw_spin_unlock_irqrestore(&rnp->lock, flags);
-}
-
-/*
- * Initialize a new grace period.  Return 0 if no grace period required.
- */
-static int rcu_gp_init(struct rcu_state *rsp)
-{
-	struct rcu_data *rdp;
-	struct rcu_node *rnp = rcu_get_root(rsp);
-
-	rcu_bind_gp_kthread();
-	raw_spin_lock_irq(&rnp->lock);
-	if (rsp->gp_flags == 0) {
-		/* Spurious wakeup, tell caller to go back to sleep.  */
-		raw_spin_unlock_irq(&rnp->lock);
-		return 0;
-	}
-	rsp->gp_flags = 0; /* Clear all flags: New grace period. */
-
-	if (WARN_ON_ONCE(rcu_gp_in_progress(rsp))) {
-		/*
-		 * Grace period already in progress, don't start another.
-		 * Not supposed to be able to happen.
-		 */
-		raw_spin_unlock_irq(&rnp->lock);
-		return 0;
-	}
-
-	/* Advance to a new grace period and initialize state. */
-	record_gp_stall_check_time(rsp);
-	smp_wmb(); /* Record GP times before starting GP. */
-	rsp->gpnum++;
-	trace_rcu_grace_period(rsp->name, rsp->gpnum, TPS("start"));
-	raw_spin_unlock_irq(&rnp->lock);
-
-	/* Exclude any concurrent CPU-hotplug operations. */
-	mutex_lock(&rsp->onoff_mutex);
-
-	/*
-	 * Set the quiescent-state-needed bits in all the rcu_node
-	 * structures for all currently online CPUs in breadth-first order,
-	 * starting from the root rcu_node structure, relying on the layout
-	 * of the tree within the rsp->node[] array.  Note that other CPUs
-	 * will access only the leaves of the hierarchy, thus seeing that no
-	 * grace period is in progress, at least until the corresponding
-	 * leaf node has been initialized.  In addition, we have excluded
-	 * CPU-hotplug operations.
-	 *
-	 * The grace period cannot complete until the initialization
-	 * process finishes, because this kthread handles both.
-	 */
-	rcu_for_each_node_breadth_first(rsp, rnp) {
-		raw_spin_lock_irq(&rnp->lock);
-		rdp = this_cpu_ptr(rsp->rda);
-		rcu_preempt_check_blocked_tasks(rnp);
-		rnp->qsmask = rnp->qsmaskinit;
-		ACCESS_ONCE(rnp->gpnum) = rsp->gpnum;
-		WARN_ON_ONCE(rnp->completed != rsp->completed);
-		ACCESS_ONCE(rnp->completed) = rsp->completed;
-		if (rnp == rdp->mynode)
-			__note_gp_changes(rsp, rnp, rdp);
-		rcu_preempt_boost_start_gp(rnp);
-		trace_rcu_grace_period_init(rsp->name, rnp->gpnum,
-					    rnp->level, rnp->grplo,
-					    rnp->grphi, rnp->qsmask);
-		raw_spin_unlock_irq(&rnp->lock);
-#ifdef CONFIG_PROVE_RCU_DELAY
-		if ((prandom_u32() % (rcu_num_nodes + 1)) == 0 &&
-		    system_state == SYSTEM_RUNNING)
-			udelay(200);
-#endif /* #ifdef CONFIG_PROVE_RCU_DELAY */
-		cond_resched();
-	}
-
-	mutex_unlock(&rsp->onoff_mutex);
-	return 1;
-}
-
-/*
- * Do one round of quiescent-state forcing.
- */
-static int rcu_gp_fqs(struct rcu_state *rsp, int fqs_state_in)
-{
-	int fqs_state = fqs_state_in;
-	bool isidle = false;
-	unsigned long maxj;
-	struct rcu_node *rnp = rcu_get_root(rsp);
-
-	rsp->n_force_qs++;
-	if (fqs_state == RCU_SAVE_DYNTICK) {
-		/* Collect dyntick-idle snapshots. */
-		if (is_sysidle_rcu_state(rsp)) {
-			isidle = 1;
-			maxj = jiffies - ULONG_MAX / 4;
-		}
-		force_qs_rnp(rsp, dyntick_save_progress_counter,
-			     &isidle, &maxj);
-		rcu_sysidle_report_gp(rsp, isidle, maxj);
-		fqs_state = RCU_FORCE_QS;
-	} else {
-		/* Handle dyntick-idle and offline CPUs. */
-		isidle = 0;
-		force_qs_rnp(rsp, rcu_implicit_dynticks_qs, &isidle, &maxj);
-	}
-	/* Clear flag to prevent immediate re-entry. */
-	if (ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) {
-		raw_spin_lock_irq(&rnp->lock);
-		rsp->gp_flags &= ~RCU_GP_FLAG_FQS;
-		raw_spin_unlock_irq(&rnp->lock);
-	}
-	return fqs_state;
-}
-
-/*
- * Clean up after the old grace period.
- */
-static void rcu_gp_cleanup(struct rcu_state *rsp)
-{
-	unsigned long gp_duration;
-	int nocb = 0;
-	struct rcu_data *rdp;
-	struct rcu_node *rnp = rcu_get_root(rsp);
-
-	raw_spin_lock_irq(&rnp->lock);
-	gp_duration = jiffies - rsp->gp_start;
-	if (gp_duration > rsp->gp_max)
-		rsp->gp_max = gp_duration;
-
-	/*
-	 * We know the grace period is complete, but to everyone else
-	 * it appears to still be ongoing.  But it is also the case
-	 * that to everyone else it looks like there is nothing that
-	 * they can do to advance the grace period.  It is therefore
-	 * safe for us to drop the lock in order to mark the grace
-	 * period as completed in all of the rcu_node structures.
-	 */
-	raw_spin_unlock_irq(&rnp->lock);
-
-	/*
-	 * Propagate new ->completed value to rcu_node structures so
-	 * that other CPUs don't have to wait until the start of the next
-	 * grace period to process their callbacks.  This also avoids
-	 * some nasty RCU grace-period initialization races by forcing
-	 * the end of the current grace period to be completely recorded in
-	 * all of the rcu_node structures before the beginning of the next
-	 * grace period is recorded in any of the rcu_node structures.
-	 */
-	rcu_for_each_node_breadth_first(rsp, rnp) {
-		raw_spin_lock_irq(&rnp->lock);
-		ACCESS_ONCE(rnp->completed) = rsp->gpnum;
-		rdp = this_cpu_ptr(rsp->rda);
-		if (rnp == rdp->mynode)
-			__note_gp_changes(rsp, rnp, rdp);
-		nocb += rcu_future_gp_cleanup(rsp, rnp);
-		raw_spin_unlock_irq(&rnp->lock);
-		cond_resched();
-	}
-	rnp = rcu_get_root(rsp);
-	raw_spin_lock_irq(&rnp->lock);
-	rcu_nocb_gp_set(rnp, nocb);
-
-	rsp->completed = rsp->gpnum; /* Declare grace period done. */
-	trace_rcu_grace_period(rsp->name, rsp->completed, TPS("end"));
-	rsp->fqs_state = RCU_GP_IDLE;
-	rdp = this_cpu_ptr(rsp->rda);
-	rcu_advance_cbs(rsp, rnp, rdp);  /* Reduce false positives below. */
-	if (cpu_needs_another_gp(rsp, rdp)) {
-		rsp->gp_flags = RCU_GP_FLAG_INIT;
-		trace_rcu_grace_period(rsp->name,
-				       ACCESS_ONCE(rsp->gpnum),
-				       TPS("newreq"));
-	}
-	raw_spin_unlock_irq(&rnp->lock);
-}
-
-/*
- * Body of kthread that handles grace periods.
- */
-static int __noreturn rcu_gp_kthread(void *arg)
-{
-	int fqs_state;
-	int gf;
-	unsigned long j;
-	int ret;
-	struct rcu_state *rsp = arg;
-	struct rcu_node *rnp = rcu_get_root(rsp);
-
-	for (;;) {
-
-		/* Handle grace-period start. */
-		for (;;) {
-			trace_rcu_grace_period(rsp->name,
-					       ACCESS_ONCE(rsp->gpnum),
-					       TPS("reqwait"));
-			wait_event_interruptible(rsp->gp_wq,
-						 ACCESS_ONCE(rsp->gp_flags) &
-						 RCU_GP_FLAG_INIT);
-			if (rcu_gp_init(rsp))
-				break;
-			cond_resched();
-			flush_signals(current);
-			trace_rcu_grace_period(rsp->name,
-					       ACCESS_ONCE(rsp->gpnum),
-					       TPS("reqwaitsig"));
-		}
-
-		/* Handle quiescent-state forcing. */
-		fqs_state = RCU_SAVE_DYNTICK;
-		j = jiffies_till_first_fqs;
-		if (j > HZ) {
-			j = HZ;
-			jiffies_till_first_fqs = HZ;
-		}
-		ret = 0;
-		for (;;) {
-			if (!ret)
-				rsp->jiffies_force_qs = jiffies + j;
-			trace_rcu_grace_period(rsp->name,
-					       ACCESS_ONCE(rsp->gpnum),
-					       TPS("fqswait"));
-			ret = wait_event_interruptible_timeout(rsp->gp_wq,
-					((gf = ACCESS_ONCE(rsp->gp_flags)) &
-					 RCU_GP_FLAG_FQS) ||
-					(!ACCESS_ONCE(rnp->qsmask) &&
-					 !rcu_preempt_blocked_readers_cgp(rnp)),
-					j);
-			/* If grace period done, leave loop. */
-			if (!ACCESS_ONCE(rnp->qsmask) &&
-			    !rcu_preempt_blocked_readers_cgp(rnp))
-				break;
-			/* If time for quiescent-state forcing, do it. */
-			if (ULONG_CMP_GE(jiffies, rsp->jiffies_force_qs) ||
-			    (gf & RCU_GP_FLAG_FQS)) {
-				trace_rcu_grace_period(rsp->name,
-						       ACCESS_ONCE(rsp->gpnum),
-						       TPS("fqsstart"));
-				fqs_state = rcu_gp_fqs(rsp, fqs_state);
-				trace_rcu_grace_period(rsp->name,
-						       ACCESS_ONCE(rsp->gpnum),
-						       TPS("fqsend"));
-				cond_resched();
-			} else {
-				/* Deal with stray signal. */
-				cond_resched();
-				flush_signals(current);
-				trace_rcu_grace_period(rsp->name,
-						       ACCESS_ONCE(rsp->gpnum),
-						       TPS("fqswaitsig"));
-			}
-			j = jiffies_till_next_fqs;
-			if (j > HZ) {
-				j = HZ;
-				jiffies_till_next_fqs = HZ;
-			} else if (j < 1) {
-				j = 1;
-				jiffies_till_next_fqs = 1;
-			}
-		}
-
-		/* Handle grace-period end. */
-		rcu_gp_cleanup(rsp);
-	}
-}
-
-static void rsp_wakeup(struct irq_work *work)
-{
-	struct rcu_state *rsp = container_of(work, struct rcu_state, wakeup_work);
-
-	/* Wake up rcu_gp_kthread() to start the grace period. */
-	wake_up(&rsp->gp_wq);
-}
-
-/*
- * Start a new RCU grace period if warranted, re-initializing the hierarchy
- * in preparation for detecting the next grace period.  The caller must hold
- * the root node's ->lock and hard irqs must be disabled.
- *
- * Note that it is legal for a dying CPU (which is marked as offline) to
- * invoke this function.  This can happen when the dying CPU reports its
- * quiescent state.
- */
-static void
-rcu_start_gp_advanced(struct rcu_state *rsp, struct rcu_node *rnp,
-		      struct rcu_data *rdp)
-{
-	if (!rsp->gp_kthread || !cpu_needs_another_gp(rsp, rdp)) {
-		/*
-		 * Either we have not yet spawned the grace-period
-		 * task, this CPU does not need another grace period,
-		 * or a grace period is already in progress.
-		 * Either way, don't start a new grace period.
-		 */
-		return;
-	}
-	rsp->gp_flags = RCU_GP_FLAG_INIT;
-	trace_rcu_grace_period(rsp->name, ACCESS_ONCE(rsp->gpnum),
-			       TPS("newreq"));
-
-	/*
-	 * We can't do wakeups while holding the rnp->lock, as that
-	 * could cause possible deadlocks with the rq->lock. Defer
-	 * the wakeup to interrupt context.  And don't bother waking
-	 * up the running kthread.
-	 */
-	if (current != rsp->gp_kthread)
-		irq_work_queue(&rsp->wakeup_work);
-}
-
-/*
- * Similar to rcu_start_gp_advanced(), but also advance the calling CPU's
- * callbacks.  Note that rcu_start_gp_advanced() cannot do this because it
- * is invoked indirectly from rcu_advance_cbs(), which would result in
- * endless recursion -- or would do so if it wasn't for the self-deadlock
- * that is encountered beforehand.
- */
-static void
-rcu_start_gp(struct rcu_state *rsp)
-{
-	struct rcu_data *rdp = this_cpu_ptr(rsp->rda);
-	struct rcu_node *rnp = rcu_get_root(rsp);
-
-	/*
-	 * If there is no grace period in progress right now, any
-	 * callbacks we have up to this point will be satisfied by the
-	 * next grace period.  Also, advancing the callbacks reduces the
-	 * probability of false positives from cpu_needs_another_gp()
-	 * resulting in pointless grace periods.  So, advance callbacks
-	 * then start the grace period!
-	 */
-	rcu_advance_cbs(rsp, rnp, rdp);
-	rcu_start_gp_advanced(rsp, rnp, rdp);
-}
-
-/*
- * Report a full set of quiescent states to the specified rcu_state
- * data structure.  This involves cleaning up after the prior grace
- * period and letting rcu_start_gp() start up the next grace period
- * if one is needed.  Note that the caller must hold rnp->lock, which
- * is released before return.
- */
-static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags)
-	__releases(rcu_get_root(rsp)->lock)
-{
-	WARN_ON_ONCE(!rcu_gp_in_progress(rsp));
-	raw_spin_unlock_irqrestore(&rcu_get_root(rsp)->lock, flags);
-	wake_up(&rsp->gp_wq);  /* Memory barrier implied by wake_up() path. */
-}
-
-/*
- * Similar to rcu_report_qs_rdp(), for which it is a helper function.
- * Allows quiescent states for a group of CPUs to be reported at one go
- * to the specified rcu_node structure, though all the CPUs in the group
- * must be represented by the same rcu_node structure (which need not be
- * a leaf rcu_node structure, though it often will be).  That structure's
- * lock must be held upon entry, and it is released before return.
- */
-static void
-rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
-		  struct rcu_node *rnp, unsigned long flags)
-	__releases(rnp->lock)
-{
-	struct rcu_node *rnp_c;
-
-	/* Walk up the rcu_node hierarchy. */
-	for (;;) {
-		if (!(rnp->qsmask & mask)) {
-
-			/* Our bit has already been cleared, so done. */
-			raw_spin_unlock_irqrestore(&rnp->lock, flags);
-			return;
-		}
-		rnp->qsmask &= ~mask;
-		trace_rcu_quiescent_state_report(rsp->name, rnp->gpnum,
-						 mask, rnp->qsmask, rnp->level,
-						 rnp->grplo, rnp->grphi,
-						 !!rnp->gp_tasks);
-		if (rnp->qsmask != 0 || rcu_preempt_blocked_readers_cgp(rnp)) {
-
-			/* Other bits still set at this level, so done. */
-			raw_spin_unlock_irqrestore(&rnp->lock, flags);
-			return;
-		}
-		mask = rnp->grpmask;
-		if (rnp->parent == NULL) {
-
-			/* No more levels.  Exit loop holding root lock. */
-
-			break;
-		}
-		raw_spin_unlock_irqrestore(&rnp->lock, flags);
-		rnp_c = rnp;
-		rnp = rnp->parent;
-		raw_spin_lock_irqsave(&rnp->lock, flags);
-		WARN_ON_ONCE(rnp_c->qsmask);
-	}
-
-	/*
-	 * Get here if we are the last CPU to pass through a quiescent
-	 * state for this grace period.  Invoke rcu_report_qs_rsp()
-	 * to clean up and start the next grace period if one is needed.
-	 */
-	rcu_report_qs_rsp(rsp, flags); /* releases rnp->lock. */
-}
-
-/*
- * Record a quiescent state for the specified CPU to that CPU's rcu_data
- * structure.  This must be either called from the specified CPU, or
- * called when the specified CPU is known to be offline (and when it is
- * also known that no other CPU is concurrently trying to help the offline
- * CPU).  The lastcomp argument is used to make sure we are still in the
- * grace period of interest.  We don't want to end the current grace period
- * based on quiescent states detected in an earlier grace period!
- */
-static void
-rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp)
-{
-	unsigned long flags;
-	unsigned long mask;
-	struct rcu_node *rnp;
-
-	rnp = rdp->mynode;
-	raw_spin_lock_irqsave(&rnp->lock, flags);
-	if (rdp->passed_quiesce == 0 || rdp->gpnum != rnp->gpnum ||
-	    rnp->completed == rnp->gpnum) {
-
-		/*
-		 * The grace period in which this quiescent state was
-		 * recorded has ended, so don't report it upwards.
-		 * We will instead need a new quiescent state that lies
-		 * within the current grace period.
-		 */
-		rdp->passed_quiesce = 0;	/* need qs for new gp. */
-		raw_spin_unlock_irqrestore(&rnp->lock, flags);
-		return;
-	}
-	mask = rdp->grpmask;
-	if ((rnp->qsmask & mask) == 0) {
-		raw_spin_unlock_irqrestore(&rnp->lock, flags);
-	} else {
-		rdp->qs_pending = 0;
-
-		/*
-		 * This GP can't end until cpu checks in, so all of our
-		 * callbacks can be processed during the next GP.
-		 */
-		rcu_accelerate_cbs(rsp, rnp, rdp);
-
-		rcu_report_qs_rnp(mask, rsp, rnp, flags); /* rlses rnp->lock */
-	}
-}
-
-/*
- * Check to see if there is a new grace period of which this CPU
- * is not yet aware, and if so, set up local rcu_data state for it.
- * Otherwise, see if this CPU has just passed through its first
- * quiescent state for this grace period, and record that fact if so.
- */
-static void
-rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp)
-{
-	/* Check for grace-period ends and beginnings. */
-	note_gp_changes(rsp, rdp);
-
-	/*
-	 * Does this CPU still need to do its part for current grace period?
-	 * If no, return and let the other CPUs do their part as well.
-	 */
-	if (!rdp->qs_pending)
-		return;
-
-	/*
-	 * Was there a quiescent state since the beginning of the grace
-	 * period? If no, then exit and wait for the next call.
-	 */
-	if (!rdp->passed_quiesce)
-		return;
-
-	/*
-	 * Tell RCU we are done (but rcu_report_qs_rdp() will be the
-	 * judge of that).
-	 */
-	rcu_report_qs_rdp(rdp->cpu, rsp, rdp);
-}
-
-#ifdef CONFIG_HOTPLUG_CPU
-
-/*
- * Send the specified CPU's RCU callbacks to the orphanage.  The
- * specified CPU must be offline, and the caller must hold the
- * ->orphan_lock.
- */
-static void
-rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp,
-			  struct rcu_node *rnp, struct rcu_data *rdp)
-{
-	/* No-CBs CPUs do not have orphanable callbacks. */
-	if (rcu_is_nocb_cpu(rdp->cpu))
-		return;
-
-	/*
-	 * Orphan the callbacks.  First adjust the counts.  This is safe
-	 * because _rcu_barrier() excludes CPU-hotplug operations, so it
-	 * cannot be running now.  Thus no memory barrier is required.
-	 */
-	if (rdp->nxtlist != NULL) {
-		rsp->qlen_lazy += rdp->qlen_lazy;
-		rsp->qlen += rdp->qlen;
-		rdp->n_cbs_orphaned += rdp->qlen;
-		rdp->qlen_lazy = 0;
-		ACCESS_ONCE(rdp->qlen) = 0;
-	}
-
-	/*
-	 * Next, move those callbacks still needing a grace period to
-	 * the orphanage, where some other CPU will pick them up.
-	 * Some of the callbacks might have gone partway through a grace
-	 * period, but that is too bad.  They get to start over because we
-	 * cannot assume that grace periods are synchronized across CPUs.
-	 * We don't bother updating the ->nxttail[] array yet, instead
-	 * we just reset the whole thing later on.
-	 */
-	if (*rdp->nxttail[RCU_DONE_TAIL] != NULL) {
-		*rsp->orphan_nxttail = *rdp->nxttail[RCU_DONE_TAIL];
-		rsp->orphan_nxttail = rdp->nxttail[RCU_NEXT_TAIL];
-		*rdp->nxttail[RCU_DONE_TAIL] = NULL;
-	}
-
-	/*
-	 * Then move the ready-to-invoke callbacks to the orphanage,
-	 * where some other CPU will pick them up.  These will not be
-	 * required to pass though another grace period: They are done.
-	 */
-	if (rdp->nxtlist != NULL) {
-		*rsp->orphan_donetail = rdp->nxtlist;
-		rsp->orphan_donetail = rdp->nxttail[RCU_DONE_TAIL];
-	}
-
-	/* Finally, initialize the rcu_data structure's list to empty.  */
-	init_callback_list(rdp);
-}
-
-/*
- * Adopt the RCU callbacks from the specified rcu_state structure's
- * orphanage.  The caller must hold the ->orphan_lock.
- */
-static void rcu_adopt_orphan_cbs(struct rcu_state *rsp)
-{
-	int i;
-	struct rcu_data *rdp = __this_cpu_ptr(rsp->rda);
-
-	/* No-CBs CPUs are handled specially. */
-	if (rcu_nocb_adopt_orphan_cbs(rsp, rdp))
-		return;
-
-	/* Do the accounting first. */
-	rdp->qlen_lazy += rsp->qlen_lazy;
-	rdp->qlen += rsp->qlen;
-	rdp->n_cbs_adopted += rsp->qlen;
-	if (rsp->qlen_lazy != rsp->qlen)
-		rcu_idle_count_callbacks_posted();
-	rsp->qlen_lazy = 0;
-	rsp->qlen = 0;
-
-	/*
-	 * We do not need a memory barrier here because the only way we
-	 * can get here if there is an rcu_barrier() in flight is if
-	 * we are the task doing the rcu_barrier().
-	 */
-
-	/* First adopt the ready-to-invoke callbacks. */
-	if (rsp->orphan_donelist != NULL) {
-		*rsp->orphan_donetail = *rdp->nxttail[RCU_DONE_TAIL];
-		*rdp->nxttail[RCU_DONE_TAIL] = rsp->orphan_donelist;
-		for (i = RCU_NEXT_SIZE - 1; i >= RCU_DONE_TAIL; i--)
-			if (rdp->nxttail[i] == rdp->nxttail[RCU_DONE_TAIL])
-				rdp->nxttail[i] = rsp->orphan_donetail;
-		rsp->orphan_donelist = NULL;
-		rsp->orphan_donetail = &rsp->orphan_donelist;
-	}
-
-	/* And then adopt the callbacks that still need a grace period. */
-	if (rsp->orphan_nxtlist != NULL) {
-		*rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_nxtlist;
-		rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_nxttail;
-		rsp->orphan_nxtlist = NULL;
-		rsp->orphan_nxttail = &rsp->orphan_nxtlist;
-	}
-}
-
-/*
- * Trace the fact that this CPU is going offline.
- */
-static void rcu_cleanup_dying_cpu(struct rcu_state *rsp)
-{
-	RCU_TRACE(unsigned long mask);
-	RCU_TRACE(struct rcu_data *rdp = this_cpu_ptr(rsp->rda));
-	RCU_TRACE(struct rcu_node *rnp = rdp->mynode);
-
-	RCU_TRACE(mask = rdp->grpmask);
-	trace_rcu_grace_period(rsp->name,
-			       rnp->gpnum + 1 - !!(rnp->qsmask & mask),
-			       TPS("cpuofl"));
-}
-
-/*
- * The CPU has been completely removed, and some other CPU is reporting
- * this fact from process context.  Do the remainder of the cleanup,
- * including orphaning the outgoing CPU's RCU callbacks, and also
- * adopting them.  There can only be one CPU hotplug operation at a time,
- * so no other CPU can be attempting to update rcu_cpu_kthread_task.
- */
-static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
-{
-	unsigned long flags;
-	unsigned long mask;
-	int need_report = 0;
-	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
-	struct rcu_node *rnp = rdp->mynode;  /* Outgoing CPU's rdp & rnp. */
-
-	/* Adjust any no-longer-needed kthreads. */
-	rcu_boost_kthread_setaffinity(rnp, -1);
-
-	/* Remove the dead CPU from the bitmasks in the rcu_node hierarchy. */
-
-	/* Exclude any attempts to start a new grace period. */
-	mutex_lock(&rsp->onoff_mutex);
-	raw_spin_lock_irqsave(&rsp->orphan_lock, flags);
-
-	/* Orphan the dead CPU's callbacks, and adopt them if appropriate. */
-	rcu_send_cbs_to_orphanage(cpu, rsp, rnp, rdp);
-	rcu_adopt_orphan_cbs(rsp);
-
-	/* Remove the outgoing CPU from the masks in the rcu_node hierarchy. */
-	mask = rdp->grpmask;	/* rnp->grplo is constant. */
-	do {
-		raw_spin_lock(&rnp->lock);	/* irqs already disabled. */
-		rnp->qsmaskinit &= ~mask;
-		if (rnp->qsmaskinit != 0) {
-			if (rnp != rdp->mynode)
-				raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
-			break;
-		}
-		if (rnp == rdp->mynode)
-			need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp);
-		else
-			raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
-		mask = rnp->grpmask;
-		rnp = rnp->parent;
-	} while (rnp != NULL);
-
-	/*
-	 * We still hold the leaf rcu_node structure lock here, and
-	 * irqs are still disabled.  The reason for this subterfuge is
-	 * because invoking rcu_report_unblock_qs_rnp() with ->orphan_lock
-	 * held leads to deadlock.
-	 */
-	raw_spin_unlock(&rsp->orphan_lock); /* irqs remain disabled. */
-	rnp = rdp->mynode;
-	if (need_report & RCU_OFL_TASKS_NORM_GP)
-		rcu_report_unblock_qs_rnp(rnp, flags);
-	else
-		raw_spin_unlock_irqrestore(&rnp->lock, flags);
-	if (need_report & RCU_OFL_TASKS_EXP_GP)
-		rcu_report_exp_rnp(rsp, rnp, true);
-	WARN_ONCE(rdp->qlen != 0 || rdp->nxtlist != NULL,
-		  "rcu_cleanup_dead_cpu: Callbacks on offline CPU %d: qlen=%lu, nxtlist=%p\n",
-		  cpu, rdp->qlen, rdp->nxtlist);
-	init_callback_list(rdp);
-	/* Disallow further callbacks on this CPU. */
-	rdp->nxttail[RCU_NEXT_TAIL] = NULL;
-	mutex_unlock(&rsp->onoff_mutex);
-}
-
-#else /* #ifdef CONFIG_HOTPLUG_CPU */
-
-static void rcu_cleanup_dying_cpu(struct rcu_state *rsp)
-{
-}
-
-static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
-{
-}
-
-#endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
-
-/*
- * Invoke any RCU callbacks that have made it to the end of their grace
- * period.  Thottle as specified by rdp->blimit.
- */
-static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
-{
-	unsigned long flags;
-	struct rcu_head *next, *list, **tail;
-	long bl, count, count_lazy;
-	int i;
-
-	/* If no callbacks are ready, just return. */
-	if (!cpu_has_callbacks_ready_to_invoke(rdp)) {
-		trace_rcu_batch_start(rsp->name, rdp->qlen_lazy, rdp->qlen, 0);
-		trace_rcu_batch_end(rsp->name, 0, !!ACCESS_ONCE(rdp->nxtlist),
-				    need_resched(), is_idle_task(current),
-				    rcu_is_callbacks_kthread());
-		return;
-	}
-
-	/*
-	 * Extract the list of ready callbacks, disabling to prevent
-	 * races with call_rcu() from interrupt handlers.
-	 */
-	local_irq_save(flags);
-	WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
-	bl = rdp->blimit;
-	trace_rcu_batch_start(rsp->name, rdp->qlen_lazy, rdp->qlen, bl);
-	list = rdp->nxtlist;
-	rdp->nxtlist = *rdp->nxttail[RCU_DONE_TAIL];
-	*rdp->nxttail[RCU_DONE_TAIL] = NULL;
-	tail = rdp->nxttail[RCU_DONE_TAIL];
-	for (i = RCU_NEXT_SIZE - 1; i >= 0; i--)
-		if (rdp->nxttail[i] == rdp->nxttail[RCU_DONE_TAIL])
-			rdp->nxttail[i] = &rdp->nxtlist;
-	local_irq_restore(flags);
-
-	/* Invoke callbacks. */
-	count = count_lazy = 0;
-	while (list) {
-		next = list->next;
-		prefetch(next);
-		debug_rcu_head_unqueue(list);
-		if (__rcu_reclaim(rsp->name, list))
-			count_lazy++;
-		list = next;
-		/* Stop only if limit reached and CPU has something to do. */
-		if (++count >= bl &&
-		    (need_resched() ||
-		     (!is_idle_task(current) && !rcu_is_callbacks_kthread())))
-			break;
-	}
-
-	local_irq_save(flags);
-	trace_rcu_batch_end(rsp->name, count, !!list, need_resched(),
-			    is_idle_task(current),
-			    rcu_is_callbacks_kthread());
-
-	/* Update count, and requeue any remaining callbacks. */
-	if (list != NULL) {
-		*tail = rdp->nxtlist;
-		rdp->nxtlist = list;
-		for (i = 0; i < RCU_NEXT_SIZE; i++)
-			if (&rdp->nxtlist == rdp->nxttail[i])
-				rdp->nxttail[i] = tail;
-			else
-				break;
-	}
-	smp_mb(); /* List handling before counting for rcu_barrier(). */
-	rdp->qlen_lazy -= count_lazy;
-	ACCESS_ONCE(rdp->qlen) -= count;
-	rdp->n_cbs_invoked += count;
-
-	/* Reinstate batch limit if we have worked down the excess. */
-	if (rdp->blimit == LONG_MAX && rdp->qlen <= qlowmark)
-		rdp->blimit = blimit;
-
-	/* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */
-	if (rdp->qlen == 0 && rdp->qlen_last_fqs_check != 0) {
-		rdp->qlen_last_fqs_check = 0;
-		rdp->n_force_qs_snap = rsp->n_force_qs;
-	} else if (rdp->qlen < rdp->qlen_last_fqs_check - qhimark)
-		rdp->qlen_last_fqs_check = rdp->qlen;
-	WARN_ON_ONCE((rdp->nxtlist == NULL) != (rdp->qlen == 0));
-
-	local_irq_restore(flags);
-
-	/* Re-invoke RCU core processing if there are callbacks remaining. */
-	if (cpu_has_callbacks_ready_to_invoke(rdp))
-		invoke_rcu_core();
-}
-
-/*
- * Check to see if this CPU is in a non-context-switch quiescent state
- * (user mode or idle loop for rcu, non-softirq execution for rcu_bh).
- * Also schedule RCU core processing.
- *
- * This function must be called from hardirq context.  It is normally
- * invoked from the scheduling-clock interrupt.  If rcu_pending returns
- * false, there is no point in invoking rcu_check_callbacks().
- */
-void rcu_check_callbacks(int cpu, int user)
-{
-	trace_rcu_utilization(TPS("Start scheduler-tick"));
-	increment_cpu_stall_ticks();
-	if (user || rcu_is_cpu_rrupt_from_idle()) {
-
-		/*
-		 * Get here if this CPU took its interrupt from user
-		 * mode or from the idle loop, and if this is not a
-		 * nested interrupt.  In this case, the CPU is in
-		 * a quiescent state, so note it.
-		 *
-		 * No memory barrier is required here because both
-		 * rcu_sched_qs() and rcu_bh_qs() reference only CPU-local
-		 * variables that other CPUs neither access nor modify,
-		 * at least not while the corresponding CPU is online.
-		 */
-
-		rcu_sched_qs(cpu);
-		rcu_bh_qs(cpu);
-
-	} else if (!in_softirq()) {
-
-		/*
-		 * Get here if this CPU did not take its interrupt from
-		 * softirq, in other words, if it is not interrupting
-		 * a rcu_bh read-side critical section.  This is an _bh
-		 * critical section, so note it.
-		 */
-
-		rcu_bh_qs(cpu);
-	}
-	rcu_preempt_check_callbacks(cpu);
-	if (rcu_pending(cpu))
-		invoke_rcu_core();
-	trace_rcu_utilization(TPS("End scheduler-tick"));
-}
-
-/*
- * Scan the leaf rcu_node structures, processing dyntick state for any that
- * have not yet encountered a quiescent state, using the function specified.
- * Also initiate boosting for any threads blocked on the root rcu_node.
- *
- * The caller must have suppressed start of new grace periods.
- */
-static void force_qs_rnp(struct rcu_state *rsp,
-			 int (*f)(struct rcu_data *rsp, bool *isidle,
-				  unsigned long *maxj),
-			 bool *isidle, unsigned long *maxj)
-{
-	unsigned long bit;
-	int cpu;
-	unsigned long flags;
-	unsigned long mask;
-	struct rcu_node *rnp;
-
-	rcu_for_each_leaf_node(rsp, rnp) {
-		cond_resched();
-		mask = 0;
-		raw_spin_lock_irqsave(&rnp->lock, flags);
-		if (!rcu_gp_in_progress(rsp)) {
-			raw_spin_unlock_irqrestore(&rnp->lock, flags);
-			return;
-		}
-		if (rnp->qsmask == 0) {
-			rcu_initiate_boost(rnp, flags); /* releases rnp->lock */
-			continue;
-		}
-		cpu = rnp->grplo;
-		bit = 1;
-		for (; cpu <= rnp->grphi; cpu++, bit <<= 1) {
-			if ((rnp->qsmask & bit) != 0) {
-				if ((rnp->qsmaskinit & bit) != 0)
-					*isidle = 0;
-				if (f(per_cpu_ptr(rsp->rda, cpu), isidle, maxj))
-					mask |= bit;
-			}
-		}
-		if (mask != 0) {
-
-			/* rcu_report_qs_rnp() releases rnp->lock. */
-			rcu_report_qs_rnp(mask, rsp, rnp, flags);
-			continue;
-		}
-		raw_spin_unlock_irqrestore(&rnp->lock, flags);
-	}
-	rnp = rcu_get_root(rsp);
-	if (rnp->qsmask == 0) {
-		raw_spin_lock_irqsave(&rnp->lock, flags);
-		rcu_initiate_boost(rnp, flags); /* releases rnp->lock. */
-	}
-}
-
-/*
- * Force quiescent states on reluctant CPUs, and also detect which
- * CPUs are in dyntick-idle mode.
- */
-static void force_quiescent_state(struct rcu_state *rsp)
-{
-	unsigned long flags;
-	bool ret;
-	struct rcu_node *rnp;
-	struct rcu_node *rnp_old = NULL;
-
-	/* Funnel through hierarchy to reduce memory contention. */
-	rnp = per_cpu_ptr(rsp->rda, raw_smp_processor_id())->mynode;
-	for (; rnp != NULL; rnp = rnp->parent) {
-		ret = (ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) ||
-		      !raw_spin_trylock(&rnp->fqslock);
-		if (rnp_old != NULL)
-			raw_spin_unlock(&rnp_old->fqslock);
-		if (ret) {
-			rsp->n_force_qs_lh++;
-			return;
-		}
-		rnp_old = rnp;
-	}
-	/* rnp_old == rcu_get_root(rsp), rnp == NULL. */
-
-	/* Reached the root of the rcu_node tree, acquire lock. */
-	raw_spin_lock_irqsave(&rnp_old->lock, flags);
-	raw_spin_unlock(&rnp_old->fqslock);
-	if (ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) {
-		rsp->n_force_qs_lh++;
-		raw_spin_unlock_irqrestore(&rnp_old->lock, flags);
-		return;  /* Someone beat us to it. */
-	}
-	rsp->gp_flags |= RCU_GP_FLAG_FQS;
-	raw_spin_unlock_irqrestore(&rnp_old->lock, flags);
-	wake_up(&rsp->gp_wq);  /* Memory barrier implied by wake_up() path. */
-}
-
-/*
- * This does the RCU core processing work for the specified rcu_state
- * and rcu_data structures.  This may be called only from the CPU to
- * whom the rdp belongs.
- */
-static void
-__rcu_process_callbacks(struct rcu_state *rsp)
-{
-	unsigned long flags;
-	struct rcu_data *rdp = __this_cpu_ptr(rsp->rda);
-
-	WARN_ON_ONCE(rdp->beenonline == 0);
-
-	/* Update RCU state based on any recent quiescent states. */
-	rcu_check_quiescent_state(rsp, rdp);
-
-	/* Does this CPU require a not-yet-started grace period? */
-	local_irq_save(flags);
-	if (cpu_needs_another_gp(rsp, rdp)) {
-		raw_spin_lock(&rcu_get_root(rsp)->lock); /* irqs disabled. */
-		rcu_start_gp(rsp);
-		raw_spin_unlock_irqrestore(&rcu_get_root(rsp)->lock, flags);
-	} else {
-		local_irq_restore(flags);
-	}
-
-	/* If there are callbacks ready, invoke them. */
-	if (cpu_has_callbacks_ready_to_invoke(rdp))
-		invoke_rcu_callbacks(rsp, rdp);
-}
-
-/*
- * Do RCU core processing for the current CPU.
- */
-static void rcu_process_callbacks(struct softirq_action *unused)
-{
-	struct rcu_state *rsp;
-
-	if (cpu_is_offline(smp_processor_id()))
-		return;
-	trace_rcu_utilization(TPS("Start RCU core"));
-	for_each_rcu_flavor(rsp)
-		__rcu_process_callbacks(rsp);
-	trace_rcu_utilization(TPS("End RCU core"));
-}
-
-/*
- * Schedule RCU callback invocation.  If the specified type of RCU
- * does not support RCU priority boosting, just do a direct call,
- * otherwise wake up the per-CPU kernel kthread.  Note that because we
- * are running on the current CPU with interrupts disabled, the
- * rcu_cpu_kthread_task cannot disappear out from under us.
- */
-static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
-{
-	if (unlikely(!ACCESS_ONCE(rcu_scheduler_fully_active)))
-		return;
-	if (likely(!rsp->boost)) {
-		rcu_do_batch(rsp, rdp);
-		return;
-	}
-	invoke_rcu_callbacks_kthread();
-}
-
-static void invoke_rcu_core(void)
-{
-	if (cpu_online(smp_processor_id()))
-		raise_softirq(RCU_SOFTIRQ);
-}
-
-/*
- * Handle any core-RCU processing required by a call_rcu() invocation.
- */
-static void __call_rcu_core(struct rcu_state *rsp, struct rcu_data *rdp,
-			    struct rcu_head *head, unsigned long flags)
-{
-	/*
-	 * If called from an extended quiescent state, invoke the RCU
-	 * core in order to force a re-evaluation of RCU's idleness.
-	 */
-	if (!rcu_is_watching() && cpu_online(smp_processor_id()))
-		invoke_rcu_core();
-
-	/* If interrupts were disabled or CPU offline, don't invoke RCU core. */
-	if (irqs_disabled_flags(flags) || cpu_is_offline(smp_processor_id()))
-		return;
-
-	/*
-	 * Force the grace period if too many callbacks or too long waiting.
-	 * Enforce hysteresis, and don't invoke force_quiescent_state()
-	 * if some other CPU has recently done so.  Also, don't bother
-	 * invoking force_quiescent_state() if the newly enqueued callback
-	 * is the only one waiting for a grace period to complete.
-	 */
-	if (unlikely(rdp->qlen > rdp->qlen_last_fqs_check + qhimark)) {
-
-		/* Are we ignoring a completed grace period? */
-		note_gp_changes(rsp, rdp);
-
-		/* Start a new grace period if one not already started. */
-		if (!rcu_gp_in_progress(rsp)) {
-			struct rcu_node *rnp_root = rcu_get_root(rsp);
-
-			raw_spin_lock(&rnp_root->lock);
-			rcu_start_gp(rsp);
-			raw_spin_unlock(&rnp_root->lock);
-		} else {
-			/* Give the grace period a kick. */
-			rdp->blimit = LONG_MAX;
-			if (rsp->n_force_qs == rdp->n_force_qs_snap &&
-			    *rdp->nxttail[RCU_DONE_TAIL] != head)
-				force_quiescent_state(rsp);
-			rdp->n_force_qs_snap = rsp->n_force_qs;
-			rdp->qlen_last_fqs_check = rdp->qlen;
-		}
-	}
-}
-
-/*
- * RCU callback function to leak a callback.
- */
-static void rcu_leak_callback(struct rcu_head *rhp)
-{
-}
-
-/*
- * Helper function for call_rcu() and friends.  The cpu argument will
- * normally be -1, indicating "currently running CPU".  It may specify
- * a CPU only if that CPU is a no-CBs CPU.  Currently, only _rcu_barrier()
- * is expected to specify a CPU.
- */
-static void
-__call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
-	   struct rcu_state *rsp, int cpu, bool lazy)
-{
-	unsigned long flags;
-	struct rcu_data *rdp;
-
-	WARN_ON_ONCE((unsigned long)head & 0x3); /* Misaligned rcu_head! */
-	if (debug_rcu_head_queue(head)) {
-		/* Probable double call_rcu(), so leak the callback. */
-		ACCESS_ONCE(head->func) = rcu_leak_callback;
-		WARN_ONCE(1, "__call_rcu(): Leaked duplicate callback\n");
-		return;
-	}
-	head->func = func;
-	head->next = NULL;
-
-	/*
-	 * Opportunistically note grace-period endings and beginnings.
-	 * Note that we might see a beginning right after we see an
-	 * end, but never vice versa, since this CPU has to pass through
-	 * a quiescent state betweentimes.
-	 */
-	local_irq_save(flags);
-	rdp = this_cpu_ptr(rsp->rda);
-
-	/* Add the callback to our list. */
-	if (unlikely(rdp->nxttail[RCU_NEXT_TAIL] == NULL) || cpu != -1) {
-		int offline;
-
-		if (cpu != -1)
-			rdp = per_cpu_ptr(rsp->rda, cpu);
-		offline = !__call_rcu_nocb(rdp, head, lazy);
-		WARN_ON_ONCE(offline);
-		/* _call_rcu() is illegal on offline CPU; leak the callback. */
-		local_irq_restore(flags);
-		return;
-	}
-	ACCESS_ONCE(rdp->qlen)++;
-	if (lazy)
-		rdp->qlen_lazy++;
-	else
-		rcu_idle_count_callbacks_posted();
-	smp_mb();  /* Count before adding callback for rcu_barrier(). */
-	*rdp->nxttail[RCU_NEXT_TAIL] = head;
-	rdp->nxttail[RCU_NEXT_TAIL] = &head->next;
-
-	if (__is_kfree_rcu_offset((unsigned long)func))
-		trace_rcu_kfree_callback(rsp->name, head, (unsigned long)func,
-					 rdp->qlen_lazy, rdp->qlen);
-	else
-		trace_rcu_callback(rsp->name, head, rdp->qlen_lazy, rdp->qlen);
-
-	/* Go handle any RCU core processing required. */
-	__call_rcu_core(rsp, rdp, head, flags);
-	local_irq_restore(flags);
-}
-
-/*
- * Queue an RCU-sched callback for invocation after a grace period.
- */
-void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
-{
-	__call_rcu(head, func, &rcu_sched_state, -1, 0);
-}
-EXPORT_SYMBOL_GPL(call_rcu_sched);
-
-/*
- * Queue an RCU callback for invocation after a quicker grace period.
- */
-void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
-{
-	__call_rcu(head, func, &rcu_bh_state, -1, 0);
-}
-EXPORT_SYMBOL_GPL(call_rcu_bh);
-
-/*
- * Because a context switch is a grace period for RCU-sched and RCU-bh,
- * any blocking grace-period wait automatically implies a grace period
- * if there is only one CPU online at any point time during execution
- * of either synchronize_sched() or synchronize_rcu_bh().  It is OK to
- * occasionally incorrectly indicate that there are multiple CPUs online
- * when there was in fact only one the whole time, as this just adds
- * some overhead: RCU still operates correctly.
- */
-static inline int rcu_blocking_is_gp(void)
-{
-	int ret;
-
-	might_sleep();  /* Check for RCU read-side critical section. */
-	preempt_disable();
-	ret = num_online_cpus() <= 1;
-	preempt_enable();
-	return ret;
-}
-
-/**
- * synchronize_sched - wait until an rcu-sched grace period has elapsed.
- *
- * Control will return to the caller some time after a full rcu-sched
- * grace period has elapsed, in other words after all currently executing
- * rcu-sched read-side critical sections have completed.   These read-side
- * critical sections are delimited by rcu_read_lock_sched() and
- * rcu_read_unlock_sched(), and may be nested.  Note that preempt_disable(),
- * local_irq_disable(), and so on may be used in place of
- * rcu_read_lock_sched().
- *
- * This means that all preempt_disable code sequences, including NMI and
- * non-threaded hardware-interrupt handlers, in progress on entry will
- * have completed before this primitive returns.  However, this does not
- * guarantee that softirq handlers will have completed, since in some
- * kernels, these handlers can run in process context, and can block.
- *
- * Note that this guarantee implies further memory-ordering guarantees.
- * On systems with more than one CPU, when synchronize_sched() returns,
- * each CPU is guaranteed to have executed a full memory barrier since the
- * end of its last RCU-sched read-side critical section whose beginning
- * preceded the call to synchronize_sched().  In addition, each CPU having
- * an RCU read-side critical section that extends beyond the return from
- * synchronize_sched() is guaranteed to have executed a full memory barrier
- * after the beginning of synchronize_sched() and before the beginning of
- * that RCU read-side critical section.  Note that these guarantees include
- * CPUs that are offline, idle, or executing in user mode, as well as CPUs
- * that are executing in the kernel.
- *
- * Furthermore, if CPU A invoked synchronize_sched(), which returned
- * to its caller on CPU B, then both CPU A and CPU B are guaranteed
- * to have executed a full memory barrier during the execution of
- * synchronize_sched() -- even if CPU A and CPU B are the same CPU (but
- * again only if the system has more than one CPU).
- *
- * This primitive provides the guarantees made by the (now removed)
- * synchronize_kernel() API.  In contrast, synchronize_rcu() only
- * guarantees that rcu_read_lock() sections will have completed.
- * In "classic RCU", these two guarantees happen to be one and
- * the same, but can differ in realtime RCU implementations.
- */
-void synchronize_sched(void)
-{
-	rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) &&
-			   !lock_is_held(&rcu_lock_map) &&
-			   !lock_is_held(&rcu_sched_lock_map),
-			   "Illegal synchronize_sched() in RCU-sched read-side critical section");
-	if (rcu_blocking_is_gp())
-		return;
-	if (rcu_expedited)
-		synchronize_sched_expedited();
-	else
-		wait_rcu_gp(call_rcu_sched);
-}
-EXPORT_SYMBOL_GPL(synchronize_sched);
-
-/**
- * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed.
- *
- * Control will return to the caller some time after a full rcu_bh grace
- * period has elapsed, in other words after all currently executing rcu_bh
- * read-side critical sections have completed.  RCU read-side critical
- * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(),
- * and may be nested.
- *
- * See the description of synchronize_sched() for more detailed information
- * on memory ordering guarantees.
- */
-void synchronize_rcu_bh(void)
-{
-	rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) &&
-			   !lock_is_held(&rcu_lock_map) &&
-			   !lock_is_held(&rcu_sched_lock_map),
-			   "Illegal synchronize_rcu_bh() in RCU-bh read-side critical section");
-	if (rcu_blocking_is_gp())
-		return;
-	if (rcu_expedited)
-		synchronize_rcu_bh_expedited();
-	else
-		wait_rcu_gp(call_rcu_bh);
-}
-EXPORT_SYMBOL_GPL(synchronize_rcu_bh);
-
-static int synchronize_sched_expedited_cpu_stop(void *data)
-{
-	/*
-	 * There must be a full memory barrier on each affected CPU
-	 * between the time that try_stop_cpus() is called and the
-	 * time that it returns.
-	 *
-	 * In the current initial implementation of cpu_stop, the
-	 * above condition is already met when the control reaches
-	 * this point and the following smp_mb() is not strictly
-	 * necessary.  Do smp_mb() anyway for documentation and
-	 * robustness against future implementation changes.
-	 */
-	smp_mb(); /* See above comment block. */
-	return 0;
-}
-
-/**
- * synchronize_sched_expedited - Brute-force RCU-sched grace period
- *
- * Wait for an RCU-sched grace period to elapse, but use a "big hammer"
- * approach to force the grace period to end quickly.  This consumes
- * significant time on all CPUs and is unfriendly to real-time workloads,
- * so is thus not recommended for any sort of common-case code.  In fact,
- * if you are using synchronize_sched_expedited() in a loop, please
- * restructure your code to batch your updates, and then use a single
- * synchronize_sched() instead.
- *
- * Note that it is illegal to call this function while holding any lock
- * that is acquired by a CPU-hotplug notifier.  And yes, it is also illegal
- * to call this function from a CPU-hotplug notifier.  Failing to observe
- * these restriction will result in deadlock.
- *
- * This implementation can be thought of as an application of ticket
- * locking to RCU, with sync_sched_expedited_started and
- * sync_sched_expedited_done taking on the roles of the halves
- * of the ticket-lock word.  Each task atomically increments
- * sync_sched_expedited_started upon entry, snapshotting the old value,
- * then attempts to stop all the CPUs.  If this succeeds, then each
- * CPU will have executed a context switch, resulting in an RCU-sched
- * grace period.  We are then done, so we use atomic_cmpxchg() to
- * update sync_sched_expedited_done to match our snapshot -- but
- * only if someone else has not already advanced past our snapshot.
- *
- * On the other hand, if try_stop_cpus() fails, we check the value
- * of sync_sched_expedited_done.  If it has advanced past our
- * initial snapshot, then someone else must have forced a grace period
- * some time after we took our snapshot.  In this case, our work is
- * done for us, and we can simply return.  Otherwise, we try again,
- * but keep our initial snapshot for purposes of checking for someone
- * doing our work for us.
- *
- * If we fail too many times in a row, we fall back to synchronize_sched().
- */
-void synchronize_sched_expedited(void)
-{
-	long firstsnap, s, snap;
-	int trycount = 0;
-	struct rcu_state *rsp = &rcu_sched_state;
-
-	/*
-	 * If we are in danger of counter wrap, just do synchronize_sched().
-	 * By allowing sync_sched_expedited_started to advance no more than
-	 * ULONG_MAX/8 ahead of sync_sched_expedited_done, we are ensuring
-	 * that more than 3.5 billion CPUs would be required to force a
-	 * counter wrap on a 32-bit system.  Quite a few more CPUs would of
-	 * course be required on a 64-bit system.
-	 */
-	if (ULONG_CMP_GE((ulong)atomic_long_read(&rsp->expedited_start),
-			 (ulong)atomic_long_read(&rsp->expedited_done) +
-			 ULONG_MAX / 8)) {
-		synchronize_sched();
-		atomic_long_inc(&rsp->expedited_wrap);
-		return;
-	}
-
-	/*
-	 * Take a ticket.  Note that atomic_inc_return() implies a
-	 * full memory barrier.
-	 */
-	snap = atomic_long_inc_return(&rsp->expedited_start);
-	firstsnap = snap;
-	get_online_cpus();
-	WARN_ON_ONCE(cpu_is_offline(raw_smp_processor_id()));
-
-	/*
-	 * Each pass through the following loop attempts to force a
-	 * context switch on each CPU.
-	 */
-	while (try_stop_cpus(cpu_online_mask,
-			     synchronize_sched_expedited_cpu_stop,
-			     NULL) == -EAGAIN) {
-		put_online_cpus();
-		atomic_long_inc(&rsp->expedited_tryfail);
-
-		/* Check to see if someone else did our work for us. */
-		s = atomic_long_read(&rsp->expedited_done);
-		if (ULONG_CMP_GE((ulong)s, (ulong)firstsnap)) {
-			/* ensure test happens before caller kfree */
-			smp_mb__before_atomic_inc(); /* ^^^ */
-			atomic_long_inc(&rsp->expedited_workdone1);
-			return;
-		}
-
-		/* No joy, try again later.  Or just synchronize_sched(). */
-		if (trycount++ < 10) {
-			udelay(trycount * num_online_cpus());
-		} else {
-			wait_rcu_gp(call_rcu_sched);
-			atomic_long_inc(&rsp->expedited_normal);
-			return;
-		}
-
-		/* Recheck to see if someone else did our work for us. */
-		s = atomic_long_read(&rsp->expedited_done);
-		if (ULONG_CMP_GE((ulong)s, (ulong)firstsnap)) {
-			/* ensure test happens before caller kfree */
-			smp_mb__before_atomic_inc(); /* ^^^ */
-			atomic_long_inc(&rsp->expedited_workdone2);
-			return;
-		}
-
-		/*
-		 * Refetching sync_sched_expedited_started allows later
-		 * callers to piggyback on our grace period.  We retry
-		 * after they started, so our grace period works for them,
-		 * and they started after our first try, so their grace
-		 * period works for us.
-		 */
-		get_online_cpus();
-		snap = atomic_long_read(&rsp->expedited_start);
-		smp_mb(); /* ensure read is before try_stop_cpus(). */
-	}
-	atomic_long_inc(&rsp->expedited_stoppedcpus);
-
-	/*
-	 * Everyone up to our most recent fetch is covered by our grace
-	 * period.  Update the counter, but only if our work is still
-	 * relevant -- which it won't be if someone who started later
-	 * than we did already did their update.
-	 */
-	do {
-		atomic_long_inc(&rsp->expedited_done_tries);
-		s = atomic_long_read(&rsp->expedited_done);
-		if (ULONG_CMP_GE((ulong)s, (ulong)snap)) {
-			/* ensure test happens before caller kfree */
-			smp_mb__before_atomic_inc(); /* ^^^ */
-			atomic_long_inc(&rsp->expedited_done_lost);
-			break;
-		}
-	} while (atomic_long_cmpxchg(&rsp->expedited_done, s, snap) != s);
-	atomic_long_inc(&rsp->expedited_done_exit);
-
-	put_online_cpus();
-}
-EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
-
-/*
- * Check to see if there is any immediate RCU-related work to be done
- * by the current CPU, for the specified type of RCU, returning 1 if so.
- * The checks are in order of increasing expense: checks that can be
- * carried out against CPU-local state are performed first.  However,
- * we must check for CPU stalls first, else we might not get a chance.
- */
-static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
-{
-	struct rcu_node *rnp = rdp->mynode;
-
-	rdp->n_rcu_pending++;
-
-	/* Check for CPU stalls, if enabled. */
-	check_cpu_stall(rsp, rdp);
-
-	/* Is the RCU core waiting for a quiescent state from this CPU? */
-	if (rcu_scheduler_fully_active &&
-	    rdp->qs_pending && !rdp->passed_quiesce) {
-		rdp->n_rp_qs_pending++;
-	} else if (rdp->qs_pending && rdp->passed_quiesce) {
-		rdp->n_rp_report_qs++;
-		return 1;
-	}
-
-	/* Does this CPU have callbacks ready to invoke? */
-	if (cpu_has_callbacks_ready_to_invoke(rdp)) {
-		rdp->n_rp_cb_ready++;
-		return 1;
-	}
-
-	/* Has RCU gone idle with this CPU needing another grace period? */
-	if (cpu_needs_another_gp(rsp, rdp)) {
-		rdp->n_rp_cpu_needs_gp++;
-		return 1;
-	}
-
-	/* Has another RCU grace period completed?  */
-	if (ACCESS_ONCE(rnp->completed) != rdp->completed) { /* outside lock */
-		rdp->n_rp_gp_completed++;
-		return 1;
-	}
-
-	/* Has a new RCU grace period started? */
-	if (ACCESS_ONCE(rnp->gpnum) != rdp->gpnum) { /* outside lock */
-		rdp->n_rp_gp_started++;
-		return 1;
-	}
-
-	/* nothing to do */
-	rdp->n_rp_need_nothing++;
-	return 0;
-}
-
-/*
- * Check to see if there is any immediate RCU-related work to be done
- * by the current CPU, returning 1 if so.  This function is part of the
- * RCU implementation; it is -not- an exported member of the RCU API.
- */
-static int rcu_pending(int cpu)
-{
-	struct rcu_state *rsp;
-
-	for_each_rcu_flavor(rsp)
-		if (__rcu_pending(rsp, per_cpu_ptr(rsp->rda, cpu)))
-			return 1;
-	return 0;
-}
-
-/*
- * Return true if the specified CPU has any callback.  If all_lazy is
- * non-NULL, store an indication of whether all callbacks are lazy.
- * (If there are no callbacks, all of them are deemed to be lazy.)
- */
-static int rcu_cpu_has_callbacks(int cpu, bool *all_lazy)
-{
-	bool al = true;
-	bool hc = false;
-	struct rcu_data *rdp;
-	struct rcu_state *rsp;
-
-	for_each_rcu_flavor(rsp) {
-		rdp = per_cpu_ptr(rsp->rda, cpu);
-		if (!rdp->nxtlist)
-			continue;
-		hc = true;
-		if (rdp->qlen != rdp->qlen_lazy || !all_lazy) {
-			al = false;
-			break;
-		}
-	}
-	if (all_lazy)
-		*all_lazy = al;
-	return hc;
-}
-
-/*
- * Helper function for _rcu_barrier() tracing.  If tracing is disabled,
- * the compiler is expected to optimize this away.
- */
-static void _rcu_barrier_trace(struct rcu_state *rsp, const char *s,
-			       int cpu, unsigned long done)
-{
-	trace_rcu_barrier(rsp->name, s, cpu,
-			  atomic_read(&rsp->barrier_cpu_count), done);
-}
-
-/*
- * RCU callback function for _rcu_barrier().  If we are last, wake
- * up the task executing _rcu_barrier().
- */
-static void rcu_barrier_callback(struct rcu_head *rhp)
-{
-	struct rcu_data *rdp = container_of(rhp, struct rcu_data, barrier_head);
-	struct rcu_state *rsp = rdp->rsp;
-
-	if (atomic_dec_and_test(&rsp->barrier_cpu_count)) {
-		_rcu_barrier_trace(rsp, "LastCB", -1, rsp->n_barrier_done);
-		complete(&rsp->barrier_completion);
-	} else {
-		_rcu_barrier_trace(rsp, "CB", -1, rsp->n_barrier_done);
-	}
-}
-
-/*
- * Called with preemption disabled, and from cross-cpu IRQ context.
- */
-static void rcu_barrier_func(void *type)
-{
-	struct rcu_state *rsp = type;
-	struct rcu_data *rdp = __this_cpu_ptr(rsp->rda);
-
-	_rcu_barrier_trace(rsp, "IRQ", -1, rsp->n_barrier_done);
-	atomic_inc(&rsp->barrier_cpu_count);
-	rsp->call(&rdp->barrier_head, rcu_barrier_callback);
-}
-
-/*
- * Orchestrate the specified type of RCU barrier, waiting for all
- * RCU callbacks of the specified type to complete.
- */
-static void _rcu_barrier(struct rcu_state *rsp)
-{
-	int cpu;
-	struct rcu_data *rdp;
-	unsigned long snap = ACCESS_ONCE(rsp->n_barrier_done);
-	unsigned long snap_done;
-
-	_rcu_barrier_trace(rsp, "Begin", -1, snap);
-
-	/* Take mutex to serialize concurrent rcu_barrier() requests. */
-	mutex_lock(&rsp->barrier_mutex);
-
-	/*
-	 * Ensure that all prior references, including to ->n_barrier_done,
-	 * are ordered before the _rcu_barrier() machinery.
-	 */
-	smp_mb();  /* See above block comment. */
-
-	/*
-	 * Recheck ->n_barrier_done to see if others did our work for us.
-	 * This means checking ->n_barrier_done for an even-to-odd-to-even
-	 * transition.  The "if" expression below therefore rounds the old
-	 * value up to the next even number and adds two before comparing.
-	 */
-	snap_done = rsp->n_barrier_done;
-	_rcu_barrier_trace(rsp, "Check", -1, snap_done);
-
-	/*
-	 * If the value in snap is odd, we needed to wait for the current
-	 * rcu_barrier() to complete, then wait for the next one, in other
-	 * words, we need the value of snap_done to be three larger than
-	 * the value of snap.  On the other hand, if the value in snap is
-	 * even, we only had to wait for the next rcu_barrier() to complete,
-	 * in other words, we need the value of snap_done to be only two
-	 * greater than the value of snap.  The "(snap + 3) & ~0x1" computes
-	 * this for us (thank you, Linus!).
-	 */
-	if (ULONG_CMP_GE(snap_done, (snap + 3) & ~0x1)) {
-		_rcu_barrier_trace(rsp, "EarlyExit", -1, snap_done);
-		smp_mb(); /* caller's subsequent code after above check. */
-		mutex_unlock(&rsp->barrier_mutex);
-		return;
-	}
-
-	/*
-	 * Increment ->n_barrier_done to avoid duplicate work.  Use
-	 * ACCESS_ONCE() to prevent the compiler from speculating
-	 * the increment to precede the early-exit check.
-	 */
-	ACCESS_ONCE(rsp->n_barrier_done)++;
-	WARN_ON_ONCE((rsp->n_barrier_done & 0x1) != 1);
-	_rcu_barrier_trace(rsp, "Inc1", -1, rsp->n_barrier_done);
-	smp_mb(); /* Order ->n_barrier_done increment with below mechanism. */
-
-	/*
-	 * Initialize the count to one rather than to zero in order to
-	 * avoid a too-soon return to zero in case of a short grace period
-	 * (or preemption of this task).  Exclude CPU-hotplug operations
-	 * to ensure that no offline CPU has callbacks queued.
-	 */
-	init_completion(&rsp->barrier_completion);
-	atomic_set(&rsp->barrier_cpu_count, 1);
-	get_online_cpus();
-
-	/*
-	 * Force each CPU with callbacks to register a new callback.
-	 * When that callback is invoked, we will know that all of the
-	 * corresponding CPU's preceding callbacks have been invoked.
-	 */
-	for_each_possible_cpu(cpu) {
-		if (!cpu_online(cpu) && !rcu_is_nocb_cpu(cpu))
-			continue;
-		rdp = per_cpu_ptr(rsp->rda, cpu);
-		if (rcu_is_nocb_cpu(cpu)) {
-			_rcu_barrier_trace(rsp, "OnlineNoCB", cpu,
-					   rsp->n_barrier_done);
-			atomic_inc(&rsp->barrier_cpu_count);
-			__call_rcu(&rdp->barrier_head, rcu_barrier_callback,
-				   rsp, cpu, 0);
-		} else if (ACCESS_ONCE(rdp->qlen)) {
-			_rcu_barrier_trace(rsp, "OnlineQ", cpu,
-					   rsp->n_barrier_done);
-			smp_call_function_single(cpu, rcu_barrier_func, rsp, 1);
-		} else {
-			_rcu_barrier_trace(rsp, "OnlineNQ", cpu,
-					   rsp->n_barrier_done);
-		}
-	}
-	put_online_cpus();
-
-	/*
-	 * Now that we have an rcu_barrier_callback() callback on each
-	 * CPU, and thus each counted, remove the initial count.
-	 */
-	if (atomic_dec_and_test(&rsp->barrier_cpu_count))
-		complete(&rsp->barrier_completion);
-
-	/* Increment ->n_barrier_done to prevent duplicate work. */
-	smp_mb(); /* Keep increment after above mechanism. */
-	ACCESS_ONCE(rsp->n_barrier_done)++;
-	WARN_ON_ONCE((rsp->n_barrier_done & 0x1) != 0);
-	_rcu_barrier_trace(rsp, "Inc2", -1, rsp->n_barrier_done);
-	smp_mb(); /* Keep increment before caller's subsequent code. */
-
-	/* Wait for all rcu_barrier_callback() callbacks to be invoked. */
-	wait_for_completion(&rsp->barrier_completion);
-
-	/* Other rcu_barrier() invocations can now safely proceed. */
-	mutex_unlock(&rsp->barrier_mutex);
-}
-
-/**
- * rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete.
- */
-void rcu_barrier_bh(void)
-{
-	_rcu_barrier(&rcu_bh_state);
-}
-EXPORT_SYMBOL_GPL(rcu_barrier_bh);
-
-/**
- * rcu_barrier_sched - Wait for in-flight call_rcu_sched() callbacks.
- */
-void rcu_barrier_sched(void)
-{
-	_rcu_barrier(&rcu_sched_state);
-}
-EXPORT_SYMBOL_GPL(rcu_barrier_sched);
-
-/*
- * Do boot-time initialization of a CPU's per-CPU RCU data.
- */
-static void __init
-rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
-{
-	unsigned long flags;
-	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
-	struct rcu_node *rnp = rcu_get_root(rsp);
-
-	/* Set up local state, ensuring consistent view of global state. */
-	raw_spin_lock_irqsave(&rnp->lock, flags);
-	rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo);
-	init_callback_list(rdp);
-	rdp->qlen_lazy = 0;
-	ACCESS_ONCE(rdp->qlen) = 0;
-	rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
-	WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != DYNTICK_TASK_EXIT_IDLE);
-	WARN_ON_ONCE(atomic_read(&rdp->dynticks->dynticks) != 1);
-	rdp->cpu = cpu;
-	rdp->rsp = rsp;
-	rcu_boot_init_nocb_percpu_data(rdp);
-	raw_spin_unlock_irqrestore(&rnp->lock, flags);
-}
-
-/*
- * Initialize a CPU's per-CPU RCU data.  Note that only one online or
- * offline event can be happening at a given time.  Note also that we
- * can accept some slop in the rsp->completed access due to the fact
- * that this CPU cannot possibly have any RCU callbacks in flight yet.
- */
-static void
-rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptible)
-{
-	unsigned long flags;
-	unsigned long mask;
-	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
-	struct rcu_node *rnp = rcu_get_root(rsp);
-
-	/* Exclude new grace periods. */
-	mutex_lock(&rsp->onoff_mutex);
-
-	/* Set up local state, ensuring consistent view of global state. */
-	raw_spin_lock_irqsave(&rnp->lock, flags);
-	rdp->beenonline = 1;	 /* We have now been online. */
-	rdp->preemptible = preemptible;
-	rdp->qlen_last_fqs_check = 0;
-	rdp->n_force_qs_snap = rsp->n_force_qs;
-	rdp->blimit = blimit;
-	init_callback_list(rdp);  /* Re-enable callbacks on this CPU. */
-	rdp->dynticks->dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
-	rcu_sysidle_init_percpu_data(rdp->dynticks);
-	atomic_set(&rdp->dynticks->dynticks,
-		   (atomic_read(&rdp->dynticks->dynticks) & ~0x1) + 1);
-	raw_spin_unlock(&rnp->lock);		/* irqs remain disabled. */
-
-	/* Add CPU to rcu_node bitmasks. */
-	rnp = rdp->mynode;
-	mask = rdp->grpmask;
-	do {
-		/* Exclude any attempts to start a new GP on small systems. */
-		raw_spin_lock(&rnp->lock);	/* irqs already disabled. */
-		rnp->qsmaskinit |= mask;
-		mask = rnp->grpmask;
-		if (rnp == rdp->mynode) {
-			/*
-			 * If there is a grace period in progress, we will
-			 * set up to wait for it next time we run the
-			 * RCU core code.
-			 */
-			rdp->gpnum = rnp->completed;
-			rdp->completed = rnp->completed;
-			rdp->passed_quiesce = 0;
-			rdp->qs_pending = 0;
-			trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpuonl"));
-		}
-		raw_spin_unlock(&rnp->lock); /* irqs already disabled. */
-		rnp = rnp->parent;
-	} while (rnp != NULL && !(rnp->qsmaskinit & mask));
-	local_irq_restore(flags);
-
-	mutex_unlock(&rsp->onoff_mutex);
-}
-
-static void rcu_prepare_cpu(int cpu)
-{
-	struct rcu_state *rsp;
-
-	for_each_rcu_flavor(rsp)
-		rcu_init_percpu_data(cpu, rsp,
-				     strcmp(rsp->name, "rcu_preempt") == 0);
-}
-
-/*
- * Handle CPU online/offline notification events.
- */
-static int rcu_cpu_notify(struct notifier_block *self,
-				    unsigned long action, void *hcpu)
-{
-	long cpu = (long)hcpu;
-	struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu);
-	struct rcu_node *rnp = rdp->mynode;
-	struct rcu_state *rsp;
-
-	trace_rcu_utilization(TPS("Start CPU hotplug"));
-	switch (action) {
-	case CPU_UP_PREPARE:
-	case CPU_UP_PREPARE_FROZEN:
-		rcu_prepare_cpu(cpu);
-		rcu_prepare_kthreads(cpu);
-		break;
-	case CPU_ONLINE:
-	case CPU_DOWN_FAILED:
-		rcu_boost_kthread_setaffinity(rnp, -1);
-		break;
-	case CPU_DOWN_PREPARE:
-		rcu_boost_kthread_setaffinity(rnp, cpu);
-		break;
-	case CPU_DYING:
-	case CPU_DYING_FROZEN:
-		for_each_rcu_flavor(rsp)
-			rcu_cleanup_dying_cpu(rsp);
-		break;
-	case CPU_DEAD:
-	case CPU_DEAD_FROZEN:
-	case CPU_UP_CANCELED:
-	case CPU_UP_CANCELED_FROZEN:
-		for_each_rcu_flavor(rsp)
-			rcu_cleanup_dead_cpu(cpu, rsp);
-		break;
-	default:
-		break;
-	}
-	trace_rcu_utilization(TPS("End CPU hotplug"));
-	return NOTIFY_OK;
-}
-
-static int rcu_pm_notify(struct notifier_block *self,
-			 unsigned long action, void *hcpu)
-{
-	switch (action) {
-	case PM_HIBERNATION_PREPARE:
-	case PM_SUSPEND_PREPARE:
-		if (nr_cpu_ids <= 256) /* Expediting bad for large systems. */
-			rcu_expedited = 1;
-		break;
-	case PM_POST_HIBERNATION:
-	case PM_POST_SUSPEND:
-		rcu_expedited = 0;
-		break;
-	default:
-		break;
-	}
-	return NOTIFY_OK;
-}
-
-/*
- * Spawn the kthread that handles this RCU flavor's grace periods.
- */
-static int __init rcu_spawn_gp_kthread(void)
-{
-	unsigned long flags;
-	struct rcu_node *rnp;
-	struct rcu_state *rsp;
-	struct task_struct *t;
-
-	for_each_rcu_flavor(rsp) {
-		t = kthread_run(rcu_gp_kthread, rsp, "%s", rsp->name);
-		BUG_ON(IS_ERR(t));
-		rnp = rcu_get_root(rsp);
-		raw_spin_lock_irqsave(&rnp->lock, flags);
-		rsp->gp_kthread = t;
-		raw_spin_unlock_irqrestore(&rnp->lock, flags);
-		rcu_spawn_nocb_kthreads(rsp);
-	}
-	return 0;
-}
-early_initcall(rcu_spawn_gp_kthread);
-
-/*
- * This function is invoked towards the end of the scheduler's initialization
- * process.  Before this is called, the idle task might contain
- * RCU read-side critical sections (during which time, this idle
- * task is booting the system).  After this function is called, the
- * idle tasks are prohibited from containing RCU read-side critical
- * sections.  This function also enables RCU lockdep checking.
- */
-void rcu_scheduler_starting(void)
-{
-	WARN_ON(num_online_cpus() != 1);
-	WARN_ON(nr_context_switches() > 0);
-	rcu_scheduler_active = 1;
-}
-
-/*
- * Compute the per-level fanout, either using the exact fanout specified
- * or balancing the tree, depending on CONFIG_RCU_FANOUT_EXACT.
- */
-#ifdef CONFIG_RCU_FANOUT_EXACT
-static void __init rcu_init_levelspread(struct rcu_state *rsp)
-{
-	int i;
-
-	for (i = rcu_num_lvls - 1; i > 0; i--)
-		rsp->levelspread[i] = CONFIG_RCU_FANOUT;
-	rsp->levelspread[0] = rcu_fanout_leaf;
-}
-#else /* #ifdef CONFIG_RCU_FANOUT_EXACT */
-static void __init rcu_init_levelspread(struct rcu_state *rsp)
-{
-	int ccur;
-	int cprv;
-	int i;
-
-	cprv = nr_cpu_ids;
-	for (i = rcu_num_lvls - 1; i >= 0; i--) {
-		ccur = rsp->levelcnt[i];
-		rsp->levelspread[i] = (cprv + ccur - 1) / ccur;
-		cprv = ccur;
-	}
-}
-#endif /* #else #ifdef CONFIG_RCU_FANOUT_EXACT */
-
-/*
- * Helper function for rcu_init() that initializes one rcu_state structure.
- */
-static void __init rcu_init_one(struct rcu_state *rsp,
-		struct rcu_data __percpu *rda)
-{
-	static char *buf[] = { "rcu_node_0",
-			       "rcu_node_1",
-			       "rcu_node_2",
-			       "rcu_node_3" };  /* Match MAX_RCU_LVLS */
-	static char *fqs[] = { "rcu_node_fqs_0",
-			       "rcu_node_fqs_1",
-			       "rcu_node_fqs_2",
-			       "rcu_node_fqs_3" };  /* Match MAX_RCU_LVLS */
-	int cpustride = 1;
-	int i;
-	int j;
-	struct rcu_node *rnp;
-
-	BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf));  /* Fix buf[] init! */
-
-	/* Silence gcc 4.8 warning about array index out of range. */
-	if (rcu_num_lvls > RCU_NUM_LVLS)
-		panic("rcu_init_one: rcu_num_lvls overflow");
-
-	/* Initialize the level-tracking arrays. */
-
-	for (i = 0; i < rcu_num_lvls; i++)
-		rsp->levelcnt[i] = num_rcu_lvl[i];
-	for (i = 1; i < rcu_num_lvls; i++)
-		rsp->level[i] = rsp->level[i - 1] + rsp->levelcnt[i - 1];
-	rcu_init_levelspread(rsp);
-
-	/* Initialize the elements themselves, starting from the leaves. */
-
-	for (i = rcu_num_lvls - 1; i >= 0; i--) {
-		cpustride *= rsp->levelspread[i];
-		rnp = rsp->level[i];
-		for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) {
-			raw_spin_lock_init(&rnp->lock);
-			lockdep_set_class_and_name(&rnp->lock,
-						   &rcu_node_class[i], buf[i]);
-			raw_spin_lock_init(&rnp->fqslock);
-			lockdep_set_class_and_name(&rnp->fqslock,
-						   &rcu_fqs_class[i], fqs[i]);
-			rnp->gpnum = rsp->gpnum;
-			rnp->completed = rsp->completed;
-			rnp->qsmask = 0;
-			rnp->qsmaskinit = 0;
-			rnp->grplo = j * cpustride;
-			rnp->grphi = (j + 1) * cpustride - 1;
-			if (rnp->grphi >= NR_CPUS)
-				rnp->grphi = NR_CPUS - 1;
-			if (i == 0) {
-				rnp->grpnum = 0;
-				rnp->grpmask = 0;
-				rnp->parent = NULL;
-			} else {
-				rnp->grpnum = j % rsp->levelspread[i - 1];
-				rnp->grpmask = 1UL << rnp->grpnum;
-				rnp->parent = rsp->level[i - 1] +
-					      j / rsp->levelspread[i - 1];
-			}
-			rnp->level = i;
-			INIT_LIST_HEAD(&rnp->blkd_tasks);
-			rcu_init_one_nocb(rnp);
-		}
-	}
-
-	rsp->rda = rda;
-	init_waitqueue_head(&rsp->gp_wq);
-	init_irq_work(&rsp->wakeup_work, rsp_wakeup);
-	rnp = rsp->level[rcu_num_lvls - 1];
-	for_each_possible_cpu(i) {
-		while (i > rnp->grphi)
-			rnp++;
-		per_cpu_ptr(rsp->rda, i)->mynode = rnp;
-		rcu_boot_init_percpu_data(i, rsp);
-	}
-	list_add(&rsp->flavors, &rcu_struct_flavors);
-}
-
-/*
- * Compute the rcu_node tree geometry from kernel parameters.  This cannot
- * replace the definitions in rcutree.h because those are needed to size
- * the ->node array in the rcu_state structure.
- */
-static void __init rcu_init_geometry(void)
-{
-	ulong d;
-	int i;
-	int j;
-	int n = nr_cpu_ids;
-	int rcu_capacity[MAX_RCU_LVLS + 1];
-
-	/*
-	 * Initialize any unspecified boot parameters.
-	 * The default values of jiffies_till_first_fqs and
-	 * jiffies_till_next_fqs are set to the RCU_JIFFIES_TILL_FORCE_QS
-	 * value, which is a function of HZ, then adding one for each
-	 * RCU_JIFFIES_FQS_DIV CPUs that might be on the system.
-	 */
-	d = RCU_JIFFIES_TILL_FORCE_QS + nr_cpu_ids / RCU_JIFFIES_FQS_DIV;
-	if (jiffies_till_first_fqs == ULONG_MAX)
-		jiffies_till_first_fqs = d;
-	if (jiffies_till_next_fqs == ULONG_MAX)
-		jiffies_till_next_fqs = d;
-
-	/* If the compile-time values are accurate, just leave. */
-	if (rcu_fanout_leaf == CONFIG_RCU_FANOUT_LEAF &&
-	    nr_cpu_ids == NR_CPUS)
-		return;
-
-	/*
-	 * Compute number of nodes that can be handled an rcu_node tree
-	 * with the given number of levels.  Setting rcu_capacity[0] makes
-	 * some of the arithmetic easier.
-	 */
-	rcu_capacity[0] = 1;
-	rcu_capacity[1] = rcu_fanout_leaf;
-	for (i = 2; i <= MAX_RCU_LVLS; i++)
-		rcu_capacity[i] = rcu_capacity[i - 1] * CONFIG_RCU_FANOUT;
-
-	/*
-	 * The boot-time rcu_fanout_leaf parameter is only permitted
-	 * to increase the leaf-level fanout, not decrease it.  Of course,
-	 * the leaf-level fanout cannot exceed the number of bits in
-	 * the rcu_node masks.  Finally, the tree must be able to accommodate
-	 * the configured number of CPUs.  Complain and fall back to the
-	 * compile-time values if these limits are exceeded.
-	 */
-	if (rcu_fanout_leaf < CONFIG_RCU_FANOUT_LEAF ||
-	    rcu_fanout_leaf > sizeof(unsigned long) * 8 ||
-	    n > rcu_capacity[MAX_RCU_LVLS]) {
-		WARN_ON(1);
-		return;
-	}
-
-	/* Calculate the number of rcu_nodes at each level of the tree. */
-	for (i = 1; i <= MAX_RCU_LVLS; i++)
-		if (n <= rcu_capacity[i]) {
-			for (j = 0; j <= i; j++)
-				num_rcu_lvl[j] =
-					DIV_ROUND_UP(n, rcu_capacity[i - j]);
-			rcu_num_lvls = i;
-			for (j = i + 1; j <= MAX_RCU_LVLS; j++)
-				num_rcu_lvl[j] = 0;
-			break;
-		}
-
-	/* Calculate the total number of rcu_node structures. */
-	rcu_num_nodes = 0;
-	for (i = 0; i <= MAX_RCU_LVLS; i++)
-		rcu_num_nodes += num_rcu_lvl[i];
-	rcu_num_nodes -= n;
-}
-
-void __init rcu_init(void)
-{
-	int cpu;
-
-	rcu_bootup_announce();
-	rcu_init_geometry();
-	rcu_init_one(&rcu_bh_state, &rcu_bh_data);
-	rcu_init_one(&rcu_sched_state, &rcu_sched_data);
-	__rcu_init_preempt();
-	open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
-
-	/*
-	 * We don't need protection against CPU-hotplug here because
-	 * this is called early in boot, before either interrupts
-	 * or the scheduler are operational.
-	 */
-	cpu_notifier(rcu_cpu_notify, 0);
-	pm_notifier(rcu_pm_notify, 0);
-	for_each_online_cpu(cpu)
-		rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
-}
-
-#include "rcutree_plugin.h"