[PATCH v2 2/2] fscache: Add the missing smp_mb__after_atomic() before wake_up_bit()

[David Howells]

Hou Tao <houtao at huaweicloud.com> wrote:

> fscache_create_volume_work() uses wake_up_bit() to wake up the processes
> which are waiting for the completion of volume creation. According to
> comments in wake_up_bit() and waitqueue_active(), an extra smp_mb() is
> needed to guarantee the memory order between FSCACHE_VOLUME_CREATING
> flag and waitqueue_active() before invoking wake_up_bit().

What two values are you ordering?

If we're using this to create a critical section, then yes, we would need a
barrier to order the changes inside the critical section before changing the
memory location that forms the lock - but this is not a critical section.

David