2015-02-04 15:10:27

by Joerg Roedel

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

From: Joerg Roedel <[email protected]>

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 <[email protected]>
---
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);
}

--
1.8.4.5

2015-02-04 16:35:03

by Peter Zijlstra

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

On Wed, Feb 04, 2015 at 04:10:22PM +0100, Joerg Roedel wrote:
> From: Joerg Roedel <[email protected]>
>
> 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 <[email protected]>
> ---
> 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.

2015-02-04 16:36:28

by Joerg Roedel

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

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 <[email protected]>
> >
> > 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 <[email protected]>
> > ---
> > 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.

2015-02-05 11:40:23

by Joerg Roedel

Subject: [PATCH v2] iommu/amd: Use wait_event in put_pasid_state_wait

On Wed, Feb 04, 2015 at 05:34:50PM +0100, Peter Zijlstra wrote:
> You just lost your atomic_dec.

So this should be the correct version then.

>From 2a52250e542d8964c8285a37b71fe838a44c05c4 Mon Sep 17 00:00:00 2001
From: Joerg Roedel <[email protected]>
Date: Wed, 4 Feb 2015 15:50:38 +0100
Subject: [PATCH 1/2] iommu/amd: Use wait_event in put_pasid_state_wait

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 <[email protected]>
---
drivers/iommu/amd_iommu_v2.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/iommu/amd_iommu_v2.c b/drivers/iommu/amd_iommu_v2.c
index b6398d7..e01bc8f 100644
--- a/drivers/iommu/amd_iommu_v2.c
+++ b/drivers/iommu/amd_iommu_v2.c
@@ -266,14 +266,13 @@ static void put_pasid_state(struct pasid_state *pasid_state)

static void put_pasid_state_wait(struct pasid_state *pasid_state)
{
- DEFINE_WAIT(wait);
+ /* Drop our reference */
+ atomic_dec(&pasid_state->count);

- prepare_to_wait(&pasid_state->wq, &wait, TASK_UNINTERRUPTIBLE);
+ /* Wait for others to drop their references */
+ wait_event(pasid_state->wq, !atomic_read(&pasid_state->count));

- if (!atomic_dec_and_test(&pasid_state->count))
- schedule();
-
- finish_wait(&pasid_state->wq, &wait);
+ /* Get rid of it */
free_pasid_state(pasid_state);
}

--
1.8.4.5

2015-02-05 12:23:43

by Oded Gabbay

Subject: Re: [PATCH v2] iommu/amd: Use wait_event in put_pasid_state_wait

On 02/05/2015 01:40 PM, Joerg Roedel wrote:
> So this should be the correct version then.
>
> From 2a52250e542d8964c8285a37b71fe838a44c05c4 Mon Sep 17 00:00:00 2001
> From: Joerg Roedel<[email protected]>
> Date: Wed, 4 Feb 2015 15:50:38 +0100
> Subject: [PATCH 1/2] iommu/amd: Use wait_event in put_pasid_state_wait
>
> 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<[email protected]>

Tested-by: Oded Gabbay <[email protected]>

Oded