Commit-ID: b6fc6020140db437069d5bec447858fcfd64d31c
Gitweb: http://git.kernel.org/tip/b6fc6020140db437069d5bec447858fcfd64d31c
Author: Frederic Weisbecker <fweisbec@xxxxxxxxx>
AuthorDate: Mon, 28 Nov 2011 16:18:56 -0800
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Sun, 11 Dec 2011 10:32:07 -0800
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 <fweisbec@xxxxxxxxx>
Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
kernel/rcutree.c | 18 ++++++++----------
1 files changed, 8 insertions(+), 10 deletions(-)
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index bf085d7..860c02c 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);
}
--
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