Re: [PATCH 5/5] drm/omap: fix omap_gem_put_paddr() error handling

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Tomi,

Thank you for the patch.

On Thursday 18 June 2015 13:10:39 Tomi Valkeinen wrote:
> If tiler_unpin() call in omap_gem_put_paddr() fails,
> omap_gem_put_paddr() will immediately stop processing and return an
> error.
> 
> This patch remoes that error checking, and also removes
> omap_gem_put_paddr()'s return value, because:
> 
>  * The caller of omap_gem_put_paddr() can do nothing if an error
>    happens, so it's pointless to return an error value
> 
>  * If tiler_unpin() fails, the GEM object will possibly be left in an
>    undefined state, where the DMM mapping may have been removed, but the
>    GEM object still thinks everything is as it should be, leading to
>    crashes later.
> 
>  * There's no point in returning an error from a "free" call, as the
>    caller can do nothing about it. So it's better to clean up as much as
>    possible.
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
>  drivers/gpu/drm/omapdrm/omap_drv.h | 2 +-
>  drivers/gpu/drm/omapdrm/omap_gem.c | 8 +++-----
>  2 files changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/omapdrm/omap_drv.h
> b/drivers/gpu/drm/omapdrm/omap_drv.h index 2ef89c0c3006..1ae8477e4289
> 100644
> --- a/drivers/gpu/drm/omapdrm/omap_drv.h
> +++ b/drivers/gpu/drm/omapdrm/omap_drv.h
> @@ -211,7 +211,7 @@ void omap_gem_dma_sync(struct drm_gem_object *obj,
>  		enum dma_data_direction dir);
>  int omap_gem_get_paddr(struct drm_gem_object *obj,
>  		dma_addr_t *paddr, bool remap);
> -int omap_gem_put_paddr(struct drm_gem_object *obj);
> +void omap_gem_put_paddr(struct drm_gem_object *obj);
>  int omap_gem_get_pages(struct drm_gem_object *obj, struct page ***pages,
>  		bool remap);
>  int omap_gem_put_pages(struct drm_gem_object *obj);
> diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c
> b/drivers/gpu/drm/omapdrm/omap_gem.c index 51c5635aff62..d01d40245298
> 100644
> --- a/drivers/gpu/drm/omapdrm/omap_gem.c
> +++ b/drivers/gpu/drm/omapdrm/omap_gem.c
> @@ -808,10 +808,10 @@ fail:
>  /* Release physical address, when DMA is no longer being performed.. this
>   * could potentially unpin and unmap buffers from TILER
>   */
> -int omap_gem_put_paddr(struct drm_gem_object *obj)
> +void omap_gem_put_paddr(struct drm_gem_object *obj)
>  {
>  	struct omap_gem_object *omap_obj = to_omap_bo(obj);
> -	int ret = 0;
> +	int ret;
> 
>  	mutex_lock(&obj->dev->struct_mutex);
>  	if (omap_obj->paddr_cnt > 0) {
> @@ -821,7 +821,6 @@ int omap_gem_put_paddr(struct drm_gem_object *obj)
>  			if (ret) {
>  				dev_err(obj->dev->dev,
>  					"could not unpin pages: %d\n", ret);
> -				goto fail;
>  			}
>  			ret = tiler_release(omap_obj->block);
>  			if (ret) {
> @@ -832,9 +831,8 @@ int omap_gem_put_paddr(struct drm_gem_object *obj)
>  			omap_obj->block = NULL;
>  		}
>  	}
> -fail:
> +
>  	mutex_unlock(&obj->dev->struct_mutex);
> -	return ret;
>  }
> 
>  /* Get rotated scanout address (only valid if already pinned), at the

-- 
Regards,

Laurent Pinchart

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