diff options
| -rw-r--r-- | include/linux/rcupdate.h | 27 | ||||
| -rw-r--r-- | kernel/rcutiny.c | 2 | ||||
| -rw-r--r-- | kernel/rcutree.c | 2 |
3 files changed, 31 insertions, 0 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 6ee663c8745a..937217425c47 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -190,6 +190,33 @@ extern void rcu_idle_exit(void); extern void rcu_irq_enter(void); extern void rcu_irq_exit(void); +/** + * RCU_NONIDLE - Indicate idle-loop code that needs RCU readers + * @a: Code that RCU needs to pay attention to. + * + * RCU, RCU-bh, and RCU-sched read-side critical sections are forbidden + * in the inner idle loop, that is, between the rcu_idle_enter() and + * the rcu_idle_exit() -- RCU will happily ignore any such read-side + * critical sections. However, things like powertop need tracepoints + * in the inner idle loop. + * + * This macro provides the way out: RCU_NONIDLE(do_something_with_RCU()) + * will tell RCU that it needs to pay attending, invoke its argument + * (in this example, a call to the do_something_with_RCU() function), + * and then tell RCU to go back to ignoring this CPU. It is permissible + * to nest RCU_NONIDLE() wrappers, but the nesting level is currently + * quite limited. If deeper nesting is required, it will be necessary + * to adjust DYNTICK_TASK_NESTING_VALUE accordingly. + * + * This macro may be used from process-level code only. + */ +#define RCU_NONIDLE(a) \ + do { \ + rcu_idle_exit(); \ + do { a; } while (0); \ + rcu_idle_enter(); \ + } while (0) + /* * Infrastructure to implement the synchronize_() primitives in * TREE_RCU and rcu_barrier_() primitives in TINY_RCU. diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c index c8b0e1582c04..37a5444204d2 100644 --- a/kernel/rcutiny.c +++ b/kernel/rcutiny.c @@ -97,6 +97,7 @@ void rcu_idle_enter(void) rcu_idle_enter_common(oldval); local_irq_restore(flags); } +EXPORT_SYMBOL_GPL(rcu_idle_enter); /* * Exit an interrupt handler towards idle. @@ -153,6 +154,7 @@ void rcu_idle_exit(void) rcu_idle_exit_common(oldval); local_irq_restore(flags); } +EXPORT_SYMBOL_GPL(rcu_idle_exit); /* * Enter an interrupt handler, moving away from idle. diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 92b47760edf3..eacc10b03531 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -402,6 +402,7 @@ void rcu_idle_enter(void) rcu_idle_enter_common(rdtp, oldval); local_irq_restore(flags); } +EXPORT_SYMBOL_GPL(rcu_idle_enter); /** * rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle @@ -493,6 +494,7 @@ void rcu_idle_exit(void) rcu_idle_exit_common(rdtp, oldval); local_irq_restore(flags); } +EXPORT_SYMBOL_GPL(rcu_idle_exit); /** * rcu_irq_enter - inform RCU that current CPU is entering irq away from idle |