Re: [PATCH] drm/i915: Use kcalloc more

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 19 Sep 2013, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> No buffer overflows here, but better safe than sorry.
>
> v2:
> - Fixup the sizeof conversion, I've missed the pointer deref (Jani).
> - Drop the redundant GFP_ZERO, kcalloc alreads memsets (Jani).
> - Use kmalloc_array for the execbuf fastpath to avoid the memset
>   (Chris). I've opted to leave all other conversions as-is since they
>   aren't in a fastpath and dealing with cleared memory instead of
>   random garbage is just generally nicer.

Whether the change to kmalloc_array makes sense or not I leave for you
and Chris to figure out; otherwise it looks like it does what it says on
the box.

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
>  drivers/gpu/drm/i915/i915_gem_execbuffer.c | 8 +++++---
>  drivers/gpu/drm/i915/i915_gem_gtt.c        | 4 ++--
>  drivers/gpu/drm/i915/i915_gem_tiling.c     | 6 +++---
>  drivers/gpu/drm/i915/i915_gpu_error.c      | 4 ++--
>  drivers/gpu/drm/i915/intel_display.c       | 2 +-
>  5 files changed, 13 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index ee93357..ccfb8e6 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -1047,7 +1047,8 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
>  			return -EINVAL;
>  		}
>  
> -		cliprects = kmalloc(args->num_cliprects * sizeof(*cliprects),
> +		cliprects = kcalloc(args->num_cliprects,
> +				    sizeof(*cliprects),
>  				    GFP_KERNEL);
>  		if (cliprects == NULL) {
>  			ret = -ENOMEM;
> @@ -1302,8 +1303,9 @@ i915_gem_execbuffer2(struct drm_device *dev, void *data,
>  		return -EINVAL;
>  	}
>  
> -	exec2_list = kmalloc(sizeof(*exec2_list)*args->buffer_count,
> -			     GFP_TEMPORARY | __GFP_NOWARN | __GFP_NORETRY);
> +	exec2_list = kmalloc_array(args->buffer_count, sizeof(*exec2_list),
> +				   GFP_TEMPORARY |
> +				   __GFP_NOWARN | __GFP_NORETRY);
>  	if (exec2_list == NULL)
>  		exec2_list = drm_malloc_ab(sizeof(*exec2_list),
>  					   args->buffer_count);
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 212f6d8..e999496 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -336,7 +336,7 @@ static int gen6_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
>  	ppgtt->base.insert_entries = gen6_ppgtt_insert_entries;
>  	ppgtt->base.cleanup = gen6_ppgtt_cleanup;
>  	ppgtt->base.scratch = dev_priv->gtt.base.scratch;
> -	ppgtt->pt_pages = kzalloc(sizeof(struct page *)*ppgtt->num_pd_entries,
> +	ppgtt->pt_pages = kcalloc(ppgtt->num_pd_entries, sizeof(struct page *),
>  				  GFP_KERNEL);
>  	if (!ppgtt->pt_pages)
>  		return -ENOMEM;
> @@ -347,7 +347,7 @@ static int gen6_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
>  			goto err_pt_alloc;
>  	}
>  
> -	ppgtt->pt_dma_addr = kzalloc(sizeof(dma_addr_t) *ppgtt->num_pd_entries,
> +	ppgtt->pt_dma_addr = kcalloc(ppgtt->num_pd_entries, sizeof(dma_addr_t),
>  				     GFP_KERNEL);
>  	if (!ppgtt->pt_dma_addr)
>  		goto err_pt_alloc;
> diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c b/drivers/gpu/drm/i915/i915_gem_tiling.c
> index 032e9ef..ac9ebe9 100644
> --- a/drivers/gpu/drm/i915/i915_gem_tiling.c
> +++ b/drivers/gpu/drm/i915/i915_gem_tiling.c
> @@ -393,7 +393,7 @@ i915_gem_set_tiling(struct drm_device *dev, void *data,
>  	/* Try to preallocate memory required to save swizzling on put-pages */
>  	if (i915_gem_object_needs_bit17_swizzle(obj)) {
>  		if (obj->bit_17 == NULL) {
> -			obj->bit_17 = kmalloc(BITS_TO_LONGS(obj->base.size >> PAGE_SHIFT) *
> +			obj->bit_17 = kcalloc(BITS_TO_LONGS(obj->base.size >> PAGE_SHIFT),
>  					      sizeof(long), GFP_KERNEL);
>  		}
>  	} else {
> @@ -504,8 +504,8 @@ i915_gem_object_save_bit_17_swizzle(struct drm_i915_gem_object *obj)
>  	int i;
>  
>  	if (obj->bit_17 == NULL) {
> -		obj->bit_17 = kmalloc(BITS_TO_LONGS(page_count) *
> -					   sizeof(long), GFP_KERNEL);
> +		obj->bit_17 = kcalloc(BITS_TO_LONGS(page_count),
> +				      sizeof(long), GFP_KERNEL);
>  		if (obj->bit_17 == NULL) {
>  			DRM_ERROR("Failed to allocate memory for bit 17 "
>  				  "record\n");
> diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
> index c38d575..fde7c4d 100644
> --- a/drivers/gpu/drm/i915/i915_gpu_error.c
> +++ b/drivers/gpu/drm/i915/i915_gpu_error.c
> @@ -791,7 +791,7 @@ static void i915_gem_record_rings(struct drm_device *dev,
>  
>  		error->ring[i].num_requests = count;
>  		error->ring[i].requests =
> -			kmalloc(count*sizeof(struct drm_i915_error_request),
> +			kcalloc(count, sizeof(*error->ring[i].requests),
>  				GFP_ATOMIC);
>  		if (error->ring[i].requests == NULL) {
>  			error->ring[i].num_requests = 0;
> @@ -833,7 +833,7 @@ static void i915_gem_capture_vm(struct drm_i915_private *dev_priv,
>  	error->pinned_bo_count[ndx] = i - error->active_bo_count[ndx];
>  
>  	if (i) {
> -		active_bo = kmalloc(sizeof(*active_bo)*i, GFP_ATOMIC);
> +		active_bo = kcalloc(i, sizeof(*active_bo), GFP_ATOMIC);
>  		if (active_bo)
>  			pinned_bo = active_bo + error->active_bo_count[ndx];
>  	}
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index fe8db37..6b8a107 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -9031,7 +9031,7 @@ static int __intel_set_mode(struct drm_crtc *crtc,
>  	unsigned disable_pipes, prepare_pipes, modeset_pipes;
>  	int ret = 0;
>  
> -	saved_mode = kmalloc(2 * sizeof(*saved_mode), GFP_KERNEL);
> +	saved_mode = kcalloc(2, sizeof(*saved_mode), GFP_KERNEL);
>  	if (!saved_mode)
>  		return -ENOMEM;
>  	saved_hwmode = saved_mode + 1;
> -- 
> 1.8.4.rc3
>

-- 
Jani Nikula, Intel Open Source Technology Center