Messages in this thread | | | From | Waiman Long <> | Subject | Re: [PATCH] semaphore: Add might_sleep() to down_*() family | Date | Sun, 8 Aug 2021 23:01:07 -0400 |
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On 8/8/21 10:12 PM, Xiaoming Ni wrote: > Semaphore is sleeping lock. Add might_sleep() to down*() family > (with exception of down_trylock()) to detect atomic context sleep. > > Previously discussed with Peter Zijlstra, see link: > https://lore.kernel.org/lkml/20210806082320.GD22037@worktop.programming.kicks-ass.net > > Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> > --- > kernel/locking/semaphore.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/kernel/locking/semaphore.c b/kernel/locking/semaphore.c > index 9aa855a96c4a..9ee381e4d2a4 100644 > --- a/kernel/locking/semaphore.c > +++ b/kernel/locking/semaphore.c > @@ -54,6 +54,7 @@ void down(struct semaphore *sem) > { > unsigned long flags; > > + might_sleep(); > raw_spin_lock_irqsave(&sem->lock, flags); > if (likely(sem->count > 0)) > sem->count--; > @@ -77,6 +78,7 @@ int down_interruptible(struct semaphore *sem) > unsigned long flags; > int result = 0; > > + might_sleep(); > raw_spin_lock_irqsave(&sem->lock, flags); > if (likely(sem->count > 0)) > sem->count--; > @@ -103,6 +105,7 @@ int down_killable(struct semaphore *sem) > unsigned long flags; > int result = 0; > > + might_sleep(); > raw_spin_lock_irqsave(&sem->lock, flags); > if (likely(sem->count > 0)) > sem->count--; > @@ -157,6 +160,7 @@ int down_timeout(struct semaphore *sem, long timeout) > unsigned long flags; > int result = 0; > > + might_sleep(); > raw_spin_lock_irqsave(&sem->lock, flags); > if (likely(sem->count > 0)) > sem->count--;
I think it is simpler to just put a "might_sleep()" in __down_common() which is the function where sleep can actually happen.
Cheers, Longman
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