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)
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 --- drivers/gpu/drm/drm_gem_shmem_helper.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index 2a70159d50ef..9540478e0434 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -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;