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drm/shmem-helpers: Don't call get/put_pages on imported dma-buf in vmap

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There's no direct harm, because for the shmem helpers these are noops
on imported buffers. The trouble is in the locks these take - I want
to change dma_buf_vmap locking, and so need to make sure that we only
ever take certain locks on one side of the dma-buf interface: Either
for exporters, or for importers.

v2: Change the control flow less compared to what's there (Thomas)

Tested-by: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Noralf Trønnes <noralf@tronnes.org>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200514202256.490926-1-daniel.vetter@ffwll.ch
This commit is contained in:
Daniel Vetter 2020-05-14 22:22:56 +02:00
parent 3a5a5971bc
commit 0cc5fb4e87
1 changed files with 6 additions and 5 deletions
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11
drivers/gpu/drm/drm_gem_shmem_helper.c
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@ -252,15 +252,15 @@ static void *drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem)
if (shmem->vmap_use_count++ > 0)
return shmem->vaddr;
ret = drm_gem_shmem_get_pages(shmem);
if (ret)
goto err_zero_use;
if (obj->import_attach) {
shmem->vaddr = dma_buf_vmap(obj->import_attach->dmabuf);
} else {
pgprot_t prot = PAGE_KERNEL;
ret = drm_gem_shmem_get_pages(shmem);
if (ret)
goto err_zero_use;
if (!shmem->map_cached)
prot = pgprot_writecombine(prot);
shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
@ -276,7 +276,8 @@ static void *drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem)
return shmem->vaddr;
err_put_pages:
drm_gem_shmem_put_pages(shmem);
if (!obj->import_attach)
drm_gem_shmem_put_pages(shmem);
err_zero_use:
shmem->vmap_use_count = 0;