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author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2009-12-02 21:10:15 +0100 |
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committer | Ingo Molnar <mingo@elte.hu> | 2009-12-03 11:35:25 +0100 |
commit | d9a3da0699b24a589b27a61e1a5b5bd30d9db669 (patch) | |
tree | f7440e396a6c818f3cef514ccc31ab55d88025ef /kernel/rcutree.h | |
parent | rcu: Enable fourth level of TREE_RCU hierarchy (diff) | |
download | linux-d9a3da0699b24a589b27a61e1a5b5bd30d9db669.tar.xz linux-d9a3da0699b24a589b27a61e1a5b5bd30d9db669.zip |
rcu: Add expedited grace-period support for preemptible RCU
Implement an synchronize_rcu_expedited() for preemptible RCU
that actually is expedited. This uses
synchronize_sched_expedited() to force all threads currently
running in a preemptible-RCU read-side critical section onto the
appropriate ->blocked_tasks[] list, then takes a snapshot of all
of these lists and waits for them to drain.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1259784616158-git-send-email->
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/rcutree.h')
-rw-r--r-- | kernel/rcutree.h | 35 |
1 files changed, 32 insertions, 3 deletions
diff --git a/kernel/rcutree.h b/kernel/rcutree.h index df2e0b694744..d2a0046f63b2 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -104,8 +104,12 @@ struct rcu_node { /* an rcu_data structure, otherwise, each */ /* bit corresponds to a child rcu_node */ /* structure. */ + unsigned long expmask; /* Groups that have ->blocked_tasks[] */ + /* elements that need to drain to allow the */ + /* current expedited grace period to */ + /* complete (only for TREE_PREEMPT_RCU). */ unsigned long qsmaskinit; - /* Per-GP initialization for qsmask. */ + /* Per-GP initial value for qsmask & expmask. */ unsigned long grpmask; /* Mask to apply to parent qsmask. */ /* Only one bit will be set in this mask. */ int grplo; /* lowest-numbered CPU or group here. */ @@ -113,7 +117,7 @@ struct rcu_node { u8 grpnum; /* CPU/group number for next level up. */ u8 level; /* root is at level 0. */ struct rcu_node *parent; - struct list_head blocked_tasks[2]; + struct list_head blocked_tasks[4]; /* Tasks blocked in RCU read-side critsect. */ /* Grace period number (->gpnum) x blocked */ /* by tasks on the (x & 0x1) element of the */ @@ -128,6 +132,21 @@ struct rcu_node { for ((rnp) = &(rsp)->node[0]; \ (rnp) < &(rsp)->node[NUM_RCU_NODES]; (rnp)++) +/* + * Do a breadth-first scan of the non-leaf rcu_node structures for the + * specified rcu_state structure. Note that if there is a singleton + * rcu_node tree with but one rcu_node structure, this loop is a no-op. + */ +#define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \ + for ((rnp) = &(rsp)->node[0]; \ + (rnp) < (rsp)->level[NUM_RCU_LVLS - 1]; (rnp)++) + +/* + * Scan the leaves of the rcu_node hierarchy for the specified rcu_state + * structure. Note that if there is a singleton rcu_node tree with but + * one rcu_node structure, this loop -will- visit the rcu_node structure. + * It is still a leaf node, even if it is also the root node. + */ #define rcu_for_each_leaf_node(rsp, rnp) \ for ((rnp) = (rsp)->level[NUM_RCU_LVLS - 1]; \ (rnp) < &(rsp)->node[NUM_RCU_NODES]; (rnp)++) @@ -261,7 +280,7 @@ struct rcu_state { long gpnum; /* Current gp number. */ long completed; /* # of last completed gp. */ - /* End of fields guarded by root rcu_node's lock. */ + /* End of fields guarded by root rcu_node's lock. */ spinlock_t onofflock; /* exclude on/offline and */ /* starting new GP. Also */ @@ -293,6 +312,13 @@ struct rcu_state { #endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ }; +/* Return values for rcu_preempt_offline_tasks(). */ + +#define RCU_OFL_TASKS_NORM_GP 0x1 /* Tasks blocking normal */ + /* GP were moved to root. */ +#define RCU_OFL_TASKS_EXP_GP 0x2 /* Tasks blocking expedited */ + /* GP were moved to root. */ + #ifdef RCU_TREE_NONCORE /* @@ -333,6 +359,9 @@ static void rcu_preempt_offline_cpu(int cpu); static void rcu_preempt_check_callbacks(int cpu); static void rcu_preempt_process_callbacks(void); void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu)); +#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU) +static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp); +#endif /* #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU) */ static int rcu_preempt_pending(int cpu); static int rcu_preempt_needs_cpu(int cpu); static void __cpuinit rcu_preempt_init_percpu_data(int cpu); |