Re: [PATCH] iommu/amd: Use wait_event in put_pasid_state_wait

[Joerg Roedel <joro@8bytes.org>]

On Wed, Feb 04, 2015 at 05:34:50PM +0100, Peter Zijlstra wrote:
> On Wed, Feb 04, 2015 at 04:10:22PM +0100, Joerg Roedel wrote:
> > From: Joerg Roedel <jroedel@suse.de>
> > 
> > Now that I learned about possible spurious wakeups this
> > place needs fixing too. Replace the self-coded sleep variant
> > with the generic wait_event() helper.
> > 
> > Signed-off-by: Joerg Roedel <jroedel@suse.de>
> > ---
> >  drivers/iommu/amd_iommu_v2.c | 9 +--------
> >  1 file changed, 1 insertion(+), 8 deletions(-)
> > 
> > diff --git a/drivers/iommu/amd_iommu_v2.c b/drivers/iommu/amd_iommu_v2.c
> > index b6398d7..5cc1409 100644
> > --- a/drivers/iommu/amd_iommu_v2.c
> > +++ b/drivers/iommu/amd_iommu_v2.c
> > @@ -266,14 +266,7 @@ static void put_pasid_state(struct pasid_state *pasid_state)
> >  
> >  static void put_pasid_state_wait(struct pasid_state *pasid_state)
> >  {
> > -	DEFINE_WAIT(wait);
> > -
> > -	prepare_to_wait(&pasid_state->wq, &wait, TASK_UNINTERRUPTIBLE);
> > -
> > -	if (!atomic_dec_and_test(&pasid_state->count))
> > -		schedule();
> > -
> > -	finish_wait(&pasid_state->wq, &wait);
> > +	wait_event(pasid_state->wq, !atomic_read(&pasid_state->count));
> >  	free_pasid_state(pasid_state);
> >  }
> 
> You just lost your atomic_dec.

Right, thanks.