From b6fc6020140db437069d5bec447858fcfd64d31c Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Mon, 28 Nov 2011 16:18:56 -0800 Subject: [PATCH] rcu: Don't check irq nesting from rcu idle entry/exit Because tasks do not nest, rcu_idle_enter() and rcu_idle_exit() do not need to check for nesting. This commit therefore moves nesting checks from rcu_idle_enter_common() to rcu_irq_exit() and from rcu_idle_exit_common() to rcu_irq_enter(). Signed-off-by: Frederic Weisbecker Cc: Josh Triplett Signed-off-by: Paul E. McKenney --- kernel/rcutree.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index bf085d7f6a3f..860c02c7c959 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -350,10 +350,6 @@ static int rcu_implicit_offline_qs(struct rcu_data *rdp) */ static void rcu_idle_enter_common(struct rcu_dynticks *rdtp, long long oldval) { - if (rdtp->dynticks_nesting) { - trace_rcu_dyntick("--=", oldval, rdtp->dynticks_nesting); - return; - } trace_rcu_dyntick("Start", oldval, rdtp->dynticks_nesting); if (!is_idle_task(current)) { struct task_struct *idle = idle_task(smp_processor_id()); @@ -426,7 +422,10 @@ void rcu_irq_exit(void) oldval = rdtp->dynticks_nesting; rdtp->dynticks_nesting--; WARN_ON_ONCE(rdtp->dynticks_nesting < 0); - rcu_idle_enter_common(rdtp, oldval); + if (rdtp->dynticks_nesting) + trace_rcu_dyntick("--=", oldval, rdtp->dynticks_nesting); + else + rcu_idle_enter_common(rdtp, oldval); local_irq_restore(flags); } @@ -439,10 +438,6 @@ void rcu_irq_exit(void) */ static void rcu_idle_exit_common(struct rcu_dynticks *rdtp, long long oldval) { - if (oldval) { - trace_rcu_dyntick("++=", oldval, rdtp->dynticks_nesting); - return; - } 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 */ @@ -518,7 +513,10 @@ void rcu_irq_enter(void) oldval = rdtp->dynticks_nesting; rdtp->dynticks_nesting++; WARN_ON_ONCE(rdtp->dynticks_nesting == 0); - rcu_idle_exit_common(rdtp, oldval); + if (oldval) + trace_rcu_dyntick("++=", oldval, rdtp->dynticks_nesting); + else + rcu_idle_exit_common(rdtp, oldval); local_irq_restore(flags); }