[PATCH v6 4/4] drm/xe: Make dma-fences compliant with the safe access rules

[Lucas De Marchi]

On Tue, Jun 10, 2025 at 05:42:26PM +0100, Tvrtko Ursulin wrote:
>Xe can free some of the data pointed to by the dma-fences it exports. Most
>notably the timeline name can get freed if userspace closes the associated
>submit queue. At the same time the fence could have been exported to a
>third party (for example a sync_fence fd) which will then cause an use-
>after-free on subsequent access.
>
>To make this safe we need to make the driver compliant with the newly
>documented dma-fence rules. Driver has to ensure a RCU grace period
>between signalling a fence and freeing any data pointed to by said fence.
>
>For the timeline name we simply make the queue be freed via kfree_rcu and
>for the shared lock associated with multiple queues we add a RCU grace
>period before freeing the per GT structure holding the lock.
>
>Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at igalia.com>
>Reviewed-by: Matthew Brost <matthew.brost at intel.com>


Acked-by: Lucas De Marchi <lucas.demarchi at intel.com>

for merging this through drm-misc tree.

Lucas De Marchi