On 11/14/22 02:38, Dmitry Osipenko wrote:
> 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: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> Fixes: 79e2cf2e7a19 ("drm/gem: Take reservation lock for vmap/vunmap operations")
> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_gem_vram_helper.c | 18 +++---------------
> 1 file changed, 3 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c b/drivers/gpu/drm/drm_gem_vram_helper.c
> index 125160b534be..b6c7e3803bb3 100644
> --- a/drivers/gpu/drm/drm_gem_vram_helper.c
> +++ b/drivers/gpu/drm/drm_gem_vram_helper.c
> @@ -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);
>
Applied to drm-misc-next
--
Best regards,
Dmitry
