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rcu: Don't check irq nesting from rcu idle entry/exit

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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 <fweisbec@gmail.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Frederic Weisbecker 2011-11-28 16:18:56 -08:00 committed by Paul E. McKenney
parent 7cb9249900
commit b6fc602014
1 changed files with 8 additions and 10 deletions
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18
kernel/rcutree.c
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@ -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);
}