Hi
Am 11.05.20 um 11:35 schrieb Daniel Vetter:
> 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.
>
> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> Cc: Dave Airlie <airlied@xxxxxxxxxx>
> Cc: Sean Paul <sean@xxxxxxxxxx>
> Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx>
> Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Cc: Alex Deucher <alexander.deucher@xxxxxxx>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Sam Ravnborg <sam@xxxxxxxxxxxx>
> ---
> drivers/gpu/drm/udl/udl_gem.c | 22 ++++++++++++----------
> 1 file changed, 12 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/udl/udl_gem.c b/drivers/gpu/drm/udl/udl_gem.c
> index b6e26f98aa0a..c68d3e265329 100644
> --- a/drivers/gpu/drm/udl/udl_gem.c
> +++ b/drivers/gpu/drm/udl/udl_gem.c
> @@ -46,29 +46,31 @@ static void *udl_gem_object_vmap(struct drm_gem_object *obj)
It's still not clear to me why this function exists in the first place.
It's the same code as the default implementation, except that it doesn't
support cached mappings.
I don't see why udl is special. I'd suggest to try to use the original
shmem function and remove this one. Same for the mmap code.
Best regards
Thomas
> if (shmem->vmap_use_count++ > 0)
> goto out;
>
> - ret = drm_gem_shmem_get_pages(shmem);
> - if (ret)
> - goto err_zero_use;
> -
> - if (obj->import_attach)
> + if (obj->import_attach) {
> shmem->vaddr = dma_buf_vmap(obj->import_attach->dmabuf);
> - else
> + } else {
> + ret = drm_gem_shmem_get_pages(shmem);
> + if (ret)
> + goto err;
> +
> shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
> VM_MAP, PAGE_KERNEL);
>
> + if (!shmem->vaddr)
> + drm_gem_shmem_put_pages(shmem);
> + }
> +
> if (!shmem->vaddr) {
> DRM_DEBUG_KMS("Failed to vmap pages\n");
> ret = -ENOMEM;
> - goto err_put_pages;
> + goto err;
> }
>
> out:
> mutex_unlock(&shmem->vmap_lock);
> return shmem->vaddr;
>
> -err_put_pages:
> - drm_gem_shmem_put_pages(shmem);
> -err_zero_use:
> +err:
> shmem->vmap_use_count = 0;
> mutex_unlock(&shmem->vmap_lock);
> return ERR_PTR(ret);
>
--
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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