Commit 6d0bfef7 authored by Dmitry Osipenko's avatar Dmitry Osipenko
Browse files

drm/gem-vram: Fix deadlock in drm_gem_vram_vmap() 



Recently DRM framebuffer core and all drivers were moved to unlocked
vmapping functions that take the reservation lock. The drm_gem_vram_vmap()
was missed out by accident and now deadlocks drivers that use drm_gem_vram
helpers when framebuffer is updated, like Bochs driver. Remove the locking
from drm_gem_vram_v[un]map() functions to fix the deadlock.

Reported-by: default avatarDmitry Vyukov <dvyukov@google.com>
Fixes: 79e2cf2e ("drm/gem: Take reservation lock for vmap/vunmap operations")
Signed-off-by: default avatarDmitry Osipenko <dmitry.osipenko@collabora.com>
Reviewed-by: default avatarChristian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221113233850.427704-1-dmitry.osipenko@collabora.com
parent b1d39f0f

drivers/gpu/drm/drm_gem_vram_helper.c

+3 −15
Original line number Diff line number Diff line
@@ -433,25 +433,19 @@ int drm_gem_vram_vmap(struct drm_gem_vram_object *gbo, struct iosys_map *map) 
{

	int ret;



	ret = ttm_bo_reserve(&gbo->bo, true, false, NULL);

	if (ret)

		return ret;

	dma_resv_assert_held(gbo->bo.base.resv);



	ret = drm_gem_vram_pin_locked(gbo, 0);

	if (ret)

		goto err_ttm_bo_unreserve;

		return ret;

	ret = drm_gem_vram_kmap_locked(gbo, map);

	if (ret)

		goto err_drm_gem_vram_unpin_locked;



	ttm_bo_unreserve(&gbo->bo);



	return 0;



err_drm_gem_vram_unpin_locked:

	drm_gem_vram_unpin_locked(gbo);

err_ttm_bo_unreserve:

	ttm_bo_unreserve(&gbo->bo);

	return ret;

}

EXPORT_SYMBOL(drm_gem_vram_vmap);
@@ -467,16 +461,10 @@ EXPORT_SYMBOL(drm_gem_vram_vmap); 
void drm_gem_vram_vunmap(struct drm_gem_vram_object *gbo,

			 struct iosys_map *map)

{

	int ret;



	ret = ttm_bo_reserve(&gbo->bo, false, false, NULL);

	if (WARN_ONCE(ret, "ttm_bo_reserve_failed(): ret=%d\n", ret))

		return;

	dma_resv_assert_held(gbo->bo.base.resv);



	drm_gem_vram_kunmap_locked(gbo, map);

	drm_gem_vram_unpin_locked(gbo);



	ttm_bo_unreserve(&gbo->bo);

}

EXPORT_SYMBOL(drm_gem_vram_vunmap);