The following commit has been merged into the sched/urgent branch of tip: Commit-ID: 7e406d1ff39b8ee574036418a5043c86723170cf Gitweb: https://git.kernel.org/tip/7e406d1ff39b8ee574036418a5043c86723170cf Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> AuthorDate: Sat, 25 Dec 2021 01:04:57 +01:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Tue, 18 Jan 2022 12:09:59 +01:00 sched: Avoid double preemption in __cond_resched_*lock*() For PREEMPT/DYNAMIC_PREEMPT the *_unlock() will already trigger a preemption, no point in then calling preempt_schedule_common() *again*. Use _cond_resched() instead, since this is a NOP for the preemptible configs while it provide a preemption point for the others. Reported-by: xuhaifeng <xuhaifeng@xxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/YcGnvDEYBwOiV0cR@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx --- kernel/sched/core.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 0d2ab2a..56b428c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8218,9 +8218,7 @@ int __cond_resched_lock(spinlock_t *lock) if (spin_needbreak(lock) || resched) { spin_unlock(lock); - if (resched) - preempt_schedule_common(); - else + if (!_cond_resched()) cpu_relax(); ret = 1; spin_lock(lock); @@ -8238,9 +8236,7 @@ int __cond_resched_rwlock_read(rwlock_t *lock) if (rwlock_needbreak(lock) || resched) { read_unlock(lock); - if (resched) - preempt_schedule_common(); - else + if (!_cond_resched()) cpu_relax(); ret = 1; read_lock(lock); @@ -8258,9 +8254,7 @@ int __cond_resched_rwlock_write(rwlock_t *lock) if (rwlock_needbreak(lock) || resched) { write_unlock(lock); - if (resched) - preempt_schedule_common(); - else + if (!_cond_resched()) cpu_relax(); ret = 1; write_lock(lock);
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