Re: [PATCH] drm/shmem-helpers: vunmap: Don't put pages for dma-buf

[Thomas Zimmermann]

Hi

Am 19.02.21 um 13:22 schrieb Noralf Trønnes:

dma-buf importing was reworked in commit 7d2cd72a9aa3
("drm/shmem-helpers: Simplify dma-buf importing"). Before that commit
drm_gem_shmem_prime_import_sg_table() did set ->pages_use_count=1 and
drm_gem_shmem_vunmap_locked() could call drm_gem_shmem_put_pages()
unconditionally. Now without the use count set, put pages is called also
on dma-bufs. Fix this by only putting pages if it's not imported.

Fixes: 7d2cd72a9aa3 ("drm/shmem-helpers: Simplify dma-buf importing")
Cc: Daniel Vetter <daniel.vet...@ffwll.ch>
Cc: Thomas Zimmermann <tzimmerm...@suse.de>
Signed-off-by: Noralf Trønnes <nor...@tronnes.org>

Just when I saw the error. Nice. :)

Acked-by: Thomas Zimmermann <tzimmerm...@suse.de>
Tested-by: Thomas Zimmermann <tzimmerm...@suse.de>

For testing the GUD driver, you may also want to keep an eye at [1]

Best regards
Thomas

[1] https://lore.kernel.org/dri-devel/02a45c11-fc73-1e5a-3839-30b080950...@amd.com/T/#t

---
  drivers/gpu/drm/drm_gem_shmem_helper.c | 7 ++++---
  1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c 
b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 9825c378dfa6..c8a6547a1757 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -357,13 +357,14 @@ static void drm_gem_shmem_vunmap_locked(struct 
drm_gem_shmem_object *shmem,
        if (--shmem->vmap_use_count > 0)
                return;

+       if (obj->import_attach) {
                dma_buf_vunmap(obj->import_attach->dmabuf, map);
-       else
+       } else {
                vunmap(shmem->vaddr);
+               drm_gem_shmem_put_pages(shmem);
+       }

-       drm_gem_shmem_put_pages(shmem);
  }

- if (obj->import_attach) shmem->vaddr = NULL; /*

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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