Re: [PATCH] fscache: Use wake_up_var() to wake up pending volume acquisition

[David Howells]

Hou Tao <houtao@xxxxxxxxxxxxxxx> wrote:

> >  			clear_bit(FSCACHE_VOLUME_ACQUIRE_PENDING, &cursor->flags);

Maybe this should be clear_bit_unlock() instead.

And I wonder if:

	set_bit(FSCACHE_VOLUME_ACQUIRE_PENDING, &candidate->flags);

in fscache_hash_volume() needs a barrier before it.

> > -			wake_up_bit(&cursor->flags, FSCACHE_VOLUME_ACQUIRE_PENDING);
> > +			/*
> > +			 * Paired with barrier in wait_var_event(). Check
> > +			 * waitqueue_active() and wake_up_var() for details.
> > +			 */
> > +			smp_mb__after_atomic();
> > +			wake_up_var(&cursor->flags);

That doesn't seem right.

wake_up_bit() is more selective, so should be preferred to wake_up_var().

David