[PATCH 2/3] drm/i915: bail in alloc_pdp when !FULL_48BIT_PPGTT

[PATCH 2/3] drm/i915: bail in alloc_pdp when !FULL_48BIT_PPGTT

[Matthew Auld]

If we are not in FULL_48BIT_PPGTT mode then we really shouldn't
continue on with our allocations, given that the call to free_pdp would
bail early without freeing everything, thus leaking memory.

v2:
(Joonas Lahtinen)
  - tidy up with goto teardown path

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
---
 drivers/gpu/drm/i915/i915_gem_gtt.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 0d666b3..f996f4b 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -567,13 +567,16 @@ static struct
 i915_page_directory_pointer *alloc_pdp(struct drm_device *dev)
 {
 	struct i915_page_directory_pointer *pdp;
-	int ret = -ENOMEM;
+	int ret = -EINVAL;
 
-	WARN_ON(!USES_FULL_48BIT_PPGTT(dev));
+	if (WARN_ON(!USES_FULL_48BIT_PPGTT(dev)))
+		goto fail_pdp;
 
 	pdp = kzalloc(sizeof(*pdp), GFP_KERNEL);
-	if (!pdp)
-		return ERR_PTR(-ENOMEM);
+	if (!pdp) {
+		ret = -ENOMEM;
+		goto fail_pdp;
+	}
 
 	ret = __pdp_init(dev, pdp);
 	if (ret)
@@ -589,7 +592,7 @@ fail_page_m:
 	__pdp_fini(pdp);
 fail_bitmap:
 	kfree(pdp);
-
+fail_pdp:
 	return ERR_PTR(ret);
 }
 
-- 
2.5.5

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Re: [PATCH 2/3] drm/i915: bail in alloc_pdp when !FULL_48BIT_PPGTT

[Joonas Lahtinen]

On pe, 2016-04-22 at 12:05 +0100, Matthew Auld wrote:
> If we are not in FULL_48BIT_PPGTT mode then we really shouldn't
> continue on with our allocations, given that the call to free_pdp would
> bail early without freeing everything, thus leaking memory.
> 
> v2:
> (Joonas Lahtinen)
>   - tidy up with goto teardown path
> 
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_gem_gtt.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 0d666b3..f996f4b 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -567,13 +567,16 @@ static struct
>  i915_page_directory_pointer *alloc_pdp(struct drm_device *dev)
>  {
>  	struct i915_page_directory_pointer *pdp;
> -	int ret = -ENOMEM;
> +	int ret = -EINVAL;
>  
> -	WARN_ON(!USES_FULL_48BIT_PPGTT(dev));
> +	if (WARN_ON(!USES_FULL_48BIT_PPGTT(dev)))
> +		goto fail_pdp;
>  
>  	pdp = kzalloc(sizeof(*pdp), GFP_KERNEL);
> -	if (!pdp)
> -		return ERR_PTR(-ENOMEM);
> +	if (!pdp) {
> +		ret = -ENOMEM;
> +		goto fail_pdp;
> +	}
>  
>  	ret = __pdp_init(dev, pdp);
>  	if (ret)
> @@ -589,7 +592,7 @@ fail_page_m:
>  	__pdp_fini(pdp);
>  fail_bitmap:
>  	kfree(pdp);
> -
> +fail_pdp:

According to the Kernel Coding Style Chapter 7: "Centralized exiting of
functions", the naming of this label should likely just be "fail:", as
it does not free anything. The label should describe what is done under
the label, not why the label is entered (which may vary as function
grows).

With that,

Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

Regards, Joonas

>  	return ERR_PTR(ret);
>  }
>  
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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