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virgl: Don't destroy resource while it's in use. 

This is the race condition: thread 1 check reference count of resource
and then find out out it's zero and then it begin to destroy it. Around
the same time, thread 2 gets the lock and get the resource from the hash
table and plan to use it. Then this resource gets destroyed while it's
still in use.

Signed-off-by: Lepton Wu <lepton@chromium.org>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9701>
This commit is contained in:
Lepton Wu 2021-03-18 23:05:19 -07:00 committed by Marge Bot
parent bf549e4c88
commit c54fb6ef3d
1 changed files with 10 additions and 0 deletions
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10
src/gallium/winsys/virgl/drm/virgl_drm_winsys.c
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@ -72,6 +72,16 @@ static void virgl_hw_res_destroy(struct virgl_drm_winsys *qdws,
struct drm_gem_close args;
mtx_lock(&qdws->bo_handles_mutex);
/* We intentionally avoid taking the lock in
* virgl_drm_resource_reference. Now that the
* lock is taken, we need to check the refcount
* again. */
if (pipe_is_referenced(&res->reference)) {
mtx_unlock(&qdws->bo_handles_mutex);
return;
}
_mesa_hash_table_remove_key(qdws->bo_handles,
(void *)(uintptr_t)res->bo_handle);
if (res->flink_name)