Commit-ID: e3d85487fba42206024bc3ed32e4b581c7cb46db
Gitweb: https://git.kernel.org/tip/e3d85487fba42206024bc3ed32e4b581c7cb46db
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Wed, 10 Jul 2019 12:57:36 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Sat, 13 Jul 2019 11:23:27 +0200
sched/core: Fix preempt warning in ttwu
John reported a DEBUG_PREEMPT warning caused by commit:
aacedf26fb76 ("sched/core: Optimize try_to_wake_up() for local wakeups")
I overlooked that ttwu_stat() requires preemption disabled.
Reported-by: John Stultz <john.stultz@xxxxxxxxxx>
Tested-by: John Stultz <john.stultz@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Fixes: aacedf26fb76 ("sched/core: Optimize try_to_wake_up() for local wakeups")
Link: https://lkml.kernel.org/r/20190710105736.GK3402@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/sched/core.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index fa43ce3962e7..2b037f195473 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2399,6 +2399,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
unsigned long flags;
int cpu, success = 0;
+ preempt_disable();
if (p == current) {
/*
* We're waking current, this means 'p->on_rq' and 'task_cpu(p)
@@ -2412,7 +2413,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
* it disabling IRQs (this allows not taking ->pi_lock).
*/
if (!(p->state & state))
- return false;
+ goto out;
success = 1;
cpu = task_cpu(p);
@@ -2526,6 +2527,7 @@ unlock:
out:
if (success)
ttwu_stat(p, cpu, wake_flags);
+ preempt_enable();
return success;
}
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