Messages in this thread Patch in this message | | | Subject | Re: [PATCH v13 02/13] eventfd: Export eventfd_wake_count to modules | From | Jason Wang <> | Date | Wed, 1 Sep 2021 10:50:40 +0800 |
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在 2021/8/31 下午6:36, Xie Yongji 写道: > Export eventfd_wake_count so that some modules can use > the eventfd_signal_count() to check whether the > eventfd_signal() call should be deferred to a safe context. > > Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
And this matches the comment inside eventfd_signal():
/* * Deadlock or stack overflow issues can happen if we recurse here * through waitqueue wakeup handlers. If the caller users potentially * nested waitqueues with custom wakeup handlers, then it should * check eventfd_signal_count() before calling this function. If * it returns true, the eventfd_signal() call should be deferred to a * safe context. */
So:
Acked-by: Jason Wang <jasowang@redhat.com>
> --- > fs/eventfd.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/fs/eventfd.c b/fs/eventfd.c > index e265b6dd4f34..1b3130b8d6c1 100644 > --- a/fs/eventfd.c > +++ b/fs/eventfd.c > @@ -26,6 +26,7 @@ > #include <linux/uio.h> > > DEFINE_PER_CPU(int, eventfd_wake_count); > +EXPORT_PER_CPU_SYMBOL_GPL(eventfd_wake_count); > > static DEFINE_IDA(eventfd_ida); >
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