drm/xe: Don't free job in TDR

Freeing job in TDR is not safe as TDR can pass the run_job thread
resulting in UAF. It is only safe for free job to naturally be called by
the scheduler. Rather free job in TDR, add to pending list.

Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2811
Cc: Matthew Auld <matthew.auld@intel.com>
Fixes: e275d61c5f3f ("drm/xe/guc: Handle timing out of signaled jobs gracefully")
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241003001657.3517883-3-matthew.brost@intel.com
(cherry picked from commit ea2f6a77d0c40d97f4a4dc93fee4afe15d94926d)
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
index 6349500..8a9254e 100644 (file)
--- a/drivers/gpu/drm/xe/xe_guc_submit.c
+++ b/drivers/gpu/drm/xe/xe_guc_submit.c
@@ -1030,10 +1030,13 @@ guc_exec_queue_timedout_job(struct drm_sched_job *drm_job)
 
        /*
         * TDR has fired before free job worker. Common if exec queue
-        * immediately closed after last fence signaled.
+        * immediately closed after last fence signaled. Add back to pending
+        * list so job can be freed and kick scheduler ensuring free job is not
+        * lost.
         */
        if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &job->fence->flags)) {
-               guc_exec_queue_free_job(drm_job);
+               xe_sched_add_pending_job(sched, job);
+               xe_sched_submission_start(sched);
 
                return DRM_GPU_SCHED_STAT_NOMINAL;
        }