[PATCH -fixes] ttm: Don't return the bo reserved on error path

[PATCH -fixes] ttm: Don't return the bo reserved on error path

[Thomas Hellstrom]

An unlikely race could case a bo to be returned reserved on an error path.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 617b646..0bb0f5f 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -574,10 +574,16 @@ retry:
 		return ret;
 
 	spin_lock(&glob->lru_lock);
+
+	if (unlikely(list_empty(&bo->ddestroy))) {
+		spin_unlock(&glob->lru_lock);
+		return 0;
+	}
+
 	ret = ttm_bo_reserve_locked(bo, interruptible,
 				    no_wait_reserve, false, 0);
 
-	if (unlikely(ret != 0) || list_empty(&bo->ddestroy)) {
+	if (unlikely(ret != 0)) {
 		spin_unlock(&glob->lru_lock);
 		return ret;
 	}
-- 
1.7.4.4

Re: [PATCH -fixes] ttm: Don't return the bo reserved on error path

[Jerome Glisse]

On Mon, Nov 21, 2011 at 01:05:02PM +0100, Thomas Hellstrom wrote:
> An unlikely race could case a bo to be returned reserved on an error path.
> 
> Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
> ---
>  drivers/gpu/drm/ttm/ttm_bo.c |    8 +++++++-
>  1 files changed, 7 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index 617b646..0bb0f5f 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -574,10 +574,16 @@ retry:
>  		return ret;
>  
>  	spin_lock(&glob->lru_lock);
> +
> +	if (unlikely(list_empty(&bo->ddestroy))) {
> +		spin_unlock(&glob->lru_lock);
> +		return 0;
> +	}
> +
>  	ret = ttm_bo_reserve_locked(bo, interruptible,
>  				    no_wait_reserve, false, 0);
>  
> -	if (unlikely(ret != 0) || list_empty(&bo->ddestroy)) {
> +	if (unlikely(ret != 0)) {
>  		spin_unlock(&glob->lru_lock);
>  		return ret;
>  	}
> -- 
> 1.7.4.4
> 
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