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* [PATCH] drm/ttm: Warn on pinning without holding a reference
@ 2020-10-28 11:31 Daniel Vetter
  2020-10-28 11:52 ` Huang Rui
  2020-10-28 12:11 ` Christian König
  0 siblings, 2 replies; 4+ messages in thread
From: Daniel Vetter @ 2020-10-28 11:31 UTC (permalink / raw)
  To: DRI Development; +Cc: Daniel Vetter, Huang Rui, Christian Koenig, Daniel Vetter

Not technically a problem for ttm, but very likely a driver bug and
pretty big time confusing for reviewing code.

So warn about it, both at cleanup time (so we catch these for sure)
and at pin/unpin time (so we know who's the culprit).

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Christian Koenig <christian.koenig@amd.com>
Cc: Huang Rui <ray.huang@amd.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c | 2 +-
 include/drm/ttm/ttm_bo_api.h | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index f51b5e20fa17..a011072ab61d 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -509,7 +509,7 @@ static void ttm_bo_release(struct kref *kref)
 		 * shrinkers, now that they are queued for
 		 * destruction.
 		 */
-		if (bo->pin_count) {
+		if (WARN_ON(bo->pin_count)) {
 			bo->pin_count = 0;
 			ttm_bo_del_from_lru(bo);
 			ttm_bo_add_mem_to_lru(bo, &bo->mem);
diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index 37102e45e496..b45aee23d7d0 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -571,6 +571,7 @@ static inline bool ttm_bo_uses_embedded_gem_object(struct ttm_buffer_object *bo)
 static inline void ttm_bo_pin(struct ttm_buffer_object *bo)
 {
 	dma_resv_assert_held(bo->base.resv);
+	WARN_ON_ONCE(!kref_read(&bo->kref));
 	++bo->pin_count;
 }
 
@@ -584,6 +585,7 @@ static inline void ttm_bo_unpin(struct ttm_buffer_object *bo)
 {
 	dma_resv_assert_held(bo->base.resv);
 	WARN_ON_ONCE(!bo->pin_count);
+	WARN_ON_ONCE(!kref_read(&bo->kref));
 	--bo->pin_count;
 }
 
-- 
2.28.0

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [PATCH] drm/ttm: Warn on pinning without holding a reference
  2020-10-28 11:31 [PATCH] drm/ttm: Warn on pinning without holding a reference Daniel Vetter
@ 2020-10-28 11:52 ` Huang Rui
  2020-10-28 12:11 ` Christian König
  1 sibling, 0 replies; 4+ messages in thread
From: Huang Rui @ 2020-10-28 11:52 UTC (permalink / raw)
  To: Daniel Vetter; +Cc: Daniel Vetter, Koenig, Christian, DRI Development

On Wed, Oct 28, 2020 at 07:31:20PM +0800, Daniel Vetter wrote:
> Not technically a problem for ttm, but very likely a driver bug and
> pretty big time confusing for reviewing code.
> 
> So warn about it, both at cleanup time (so we catch these for sure)
> and at pin/unpin time (so we know who's the culprit).
> 
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

Reviewed-by: Huang Rui <ray.huang@amd.com>

> Cc: Christian Koenig <christian.koenig@amd.com>
> Cc: Huang Rui <ray.huang@amd.com>
> ---
>  drivers/gpu/drm/ttm/ttm_bo.c | 2 +-
>  include/drm/ttm/ttm_bo_api.h | 2 ++
>  2 files changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index f51b5e20fa17..a011072ab61d 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -509,7 +509,7 @@ static void ttm_bo_release(struct kref *kref)
>  		 * shrinkers, now that they are queued for
>  		 * destruction.
>  		 */
> -		if (bo->pin_count) {
> +		if (WARN_ON(bo->pin_count)) {
>  			bo->pin_count = 0;
>  			ttm_bo_del_from_lru(bo);
>  			ttm_bo_add_mem_to_lru(bo, &bo->mem);
> diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> index 37102e45e496..b45aee23d7d0 100644
> --- a/include/drm/ttm/ttm_bo_api.h
> +++ b/include/drm/ttm/ttm_bo_api.h
> @@ -571,6 +571,7 @@ static inline bool ttm_bo_uses_embedded_gem_object(struct ttm_buffer_object *bo)
>  static inline void ttm_bo_pin(struct ttm_buffer_object *bo)
>  {
>  	dma_resv_assert_held(bo->base.resv);
> +	WARN_ON_ONCE(!kref_read(&bo->kref));
>  	++bo->pin_count;
>  }
>  
> @@ -584,6 +585,7 @@ static inline void ttm_bo_unpin(struct ttm_buffer_object *bo)
>  {
>  	dma_resv_assert_held(bo->base.resv);
>  	WARN_ON_ONCE(!bo->pin_count);
> +	WARN_ON_ONCE(!kref_read(&bo->kref));
>  	--bo->pin_count;
>  }
>  
> -- 
> 2.28.0
> 
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH] drm/ttm: Warn on pinning without holding a reference
  2020-10-28 11:31 [PATCH] drm/ttm: Warn on pinning without holding a reference Daniel Vetter
  2020-10-28 11:52 ` Huang Rui
@ 2020-10-28 12:11 ` Christian König
  2020-11-27 15:44   ` Daniel Vetter
  1 sibling, 1 reply; 4+ messages in thread
From: Christian König @ 2020-10-28 12:11 UTC (permalink / raw)
  To: Daniel Vetter, DRI Development; +Cc: Daniel Vetter, Huang Rui

Am 28.10.20 um 12:31 schrieb Daniel Vetter:
> Not technically a problem for ttm, but very likely a driver bug and
> pretty big time confusing for reviewing code.
>
> So warn about it, both at cleanup time (so we catch these for sure)
> and at pin/unpin time (so we know who's the culprit).
>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> Cc: Christian Koenig <christian.koenig@amd.com>
> Cc: Huang Rui <ray.huang@amd.com>

Reviewed-by: Christian König <christian.koenig@amd.com>

> ---
>   drivers/gpu/drm/ttm/ttm_bo.c | 2 +-
>   include/drm/ttm/ttm_bo_api.h | 2 ++
>   2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index f51b5e20fa17..a011072ab61d 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -509,7 +509,7 @@ static void ttm_bo_release(struct kref *kref)
>   		 * shrinkers, now that they are queued for
>   		 * destruction.
>   		 */
> -		if (bo->pin_count) {
> +		if (WARN_ON(bo->pin_count)) {
>   			bo->pin_count = 0;
>   			ttm_bo_del_from_lru(bo);
>   			ttm_bo_add_mem_to_lru(bo, &bo->mem);
> diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> index 37102e45e496..b45aee23d7d0 100644
> --- a/include/drm/ttm/ttm_bo_api.h
> +++ b/include/drm/ttm/ttm_bo_api.h
> @@ -571,6 +571,7 @@ static inline bool ttm_bo_uses_embedded_gem_object(struct ttm_buffer_object *bo)
>   static inline void ttm_bo_pin(struct ttm_buffer_object *bo)
>   {
>   	dma_resv_assert_held(bo->base.resv);
> +	WARN_ON_ONCE(!kref_read(&bo->kref));
>   	++bo->pin_count;
>   }
>   
> @@ -584,6 +585,7 @@ static inline void ttm_bo_unpin(struct ttm_buffer_object *bo)
>   {
>   	dma_resv_assert_held(bo->base.resv);
>   	WARN_ON_ONCE(!bo->pin_count);
> +	WARN_ON_ONCE(!kref_read(&bo->kref));
>   	--bo->pin_count;
>   }
>   

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH] drm/ttm: Warn on pinning without holding a reference
  2020-10-28 12:11 ` Christian König
@ 2020-11-27 15:44   ` Daniel Vetter
  0 siblings, 0 replies; 4+ messages in thread
From: Daniel Vetter @ 2020-11-27 15:44 UTC (permalink / raw)
  To: Christian König
  Cc: Daniel Vetter, Huang Rui, DRI Development, Daniel Vetter

On Wed, Oct 28, 2020 at 01:11:51PM +0100, Christian König wrote:
> Am 28.10.20 um 12:31 schrieb Daniel Vetter:
> > Not technically a problem for ttm, but very likely a driver bug and
> > pretty big time confusing for reviewing code.
> > 
> > So warn about it, both at cleanup time (so we catch these for sure)
> > and at pin/unpin time (so we know who's the culprit).
> > 
> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> > Cc: Christian Koenig <christian.koenig@amd.com>
> > Cc: Huang Rui <ray.huang@amd.com>
> 
> Reviewed-by: Christian König <christian.koenig@amd.com>

Remembered this patch, pushed it. Thanks to you both for the reviews.
-Daniel

> 
> > ---
> >   drivers/gpu/drm/ttm/ttm_bo.c | 2 +-
> >   include/drm/ttm/ttm_bo_api.h | 2 ++
> >   2 files changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> > index f51b5e20fa17..a011072ab61d 100644
> > --- a/drivers/gpu/drm/ttm/ttm_bo.c
> > +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> > @@ -509,7 +509,7 @@ static void ttm_bo_release(struct kref *kref)
> >   		 * shrinkers, now that they are queued for
> >   		 * destruction.
> >   		 */
> > -		if (bo->pin_count) {
> > +		if (WARN_ON(bo->pin_count)) {
> >   			bo->pin_count = 0;
> >   			ttm_bo_del_from_lru(bo);
> >   			ttm_bo_add_mem_to_lru(bo, &bo->mem);
> > diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> > index 37102e45e496..b45aee23d7d0 100644
> > --- a/include/drm/ttm/ttm_bo_api.h
> > +++ b/include/drm/ttm/ttm_bo_api.h
> > @@ -571,6 +571,7 @@ static inline bool ttm_bo_uses_embedded_gem_object(struct ttm_buffer_object *bo)
> >   static inline void ttm_bo_pin(struct ttm_buffer_object *bo)
> >   {
> >   	dma_resv_assert_held(bo->base.resv);
> > +	WARN_ON_ONCE(!kref_read(&bo->kref));
> >   	++bo->pin_count;
> >   }
> > @@ -584,6 +585,7 @@ static inline void ttm_bo_unpin(struct ttm_buffer_object *bo)
> >   {
> >   	dma_resv_assert_held(bo->base.resv);
> >   	WARN_ON_ONCE(!bo->pin_count);
> > +	WARN_ON_ONCE(!kref_read(&bo->kref));
> >   	--bo->pin_count;
> >   }
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

^ permalink raw reply	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-11-27 15:44 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2020-10-28 11:31 [PATCH] drm/ttm: Warn on pinning without holding a reference Daniel Vetter
2020-10-28 11:52 ` Huang Rui
2020-10-28 12:11 ` Christian König
2020-11-27 15:44   ` Daniel Vetter

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