Re: [PATCH] drm/shmem-helper: Fix locking for drm_gem_shmem_get_pages_sgt()

[Javier Martinez Canillas]

Hello Lina,

On 2/5/23 13:51, Asahi Lina wrote:
> Other functions touching shmem->sgt take the pages lock, so do that here
> too. drm_gem_shmem_get_pages() & co take the same lock, so move to the
> _locked() variants to avoid recursive locking.
> 
> Discovered while auditing locking to write the Rust abstractions.
> 
> Fixes: 2194a63a818d ("drm: Add library for shmem backed GEM objects")
> Fixes: 4fa3d66f132b ("drm/shmem: Do dma_unmap_sg before purging pages")
> Signed-off-by: Asahi Lina <lina@xxxxxxxxxxxxx>
> ---

Good catch. The patch looks good to me.

Reviewed-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>

What about drm_gem_shmem_free() BTW, I believe that the helper should also
grab the lock before unmap / free the sgtable?

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat