Commit 4d2f8bc6 authored by Tvrtko Ursulin's avatar Tvrtko Ursulin Committed by Tvrtko Ursulin
Browse files

drm/i915: Protect access to driver and timeline name 



Protect the access to driver and timeline name which otherwise could be
freed as dma-fence exported is signalling fences.

This prepares the code for incoming dma-fence API changes which will start
asserting these accesses are done from a RCU locked section.

Now that the safe access is handled in the dma-fence API, the external
callers such as sync_file, and our internal code paths, we can drop the
similar protection from i915_fence_get_timeline_name().

This prepares the code for incoming dma-fence API changes which will start
asserting these accesses are done from a RCU locked section.

Signed-off-by: default avatarTvrtko Ursulin <tvrtko.ursulin@igalia.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com> # v1
Signed-off-by: default avatarTvrtko Ursulin <tursulin@ursulin.net>
Link: https://lore.kernel.org/r/20250610164226.10817-3-tvrtko.ursulin@igalia.com
parent ad10976d

drivers/gpu/drm/i915/gt/intel_gt_requests.c

+8 −2
Original line number Diff line number Diff line
@@ -250,11 +250,17 @@ void intel_gt_watchdog_work(struct work_struct *work) 
	llist_for_each_entry_safe(rq, rn, first, watchdog.link) {

		if (!i915_request_completed(rq)) {

			struct dma_fence *f = &rq->fence;

			const char __rcu *timeline;

			const char __rcu *driver;



			rcu_read_lock();

			driver = dma_fence_driver_name(f);

			timeline = dma_fence_timeline_name(f);

			pr_notice("Fence expiration time out i915-%s:%s:%llx!\n",

				  dma_fence_driver_name(f),

				  dma_fence_timeline_name(f),

				  rcu_dereference(driver),

				  rcu_dereference(timeline),

				  f->seqno);

			rcu_read_unlock();

			i915_request_cancel(rq, -EINTR);

		}

		i915_request_put(rq);

drivers/gpu/drm/i915/i915_request.c

+5 −2
Original line number Diff line number Diff line
@@ -2184,7 +2184,7 @@ void i915_request_show(struct drm_printer *m, 
		       const char *prefix,

		       int indent)

{

	const char *name = dma_fence_timeline_name((struct dma_fence *)&rq->fence);

	const char __rcu *timeline;

	char buf[80] = "";

	int x = 0;
@@ -2220,6 +2220,8 @@ void i915_request_show(struct drm_printer *m, 


	x = print_sched_attr(&rq->sched.attr, buf, x, sizeof(buf));



	rcu_read_lock();

	timeline = dma_fence_timeline_name((struct dma_fence *)&rq->fence);

	drm_printf(m, "%s%.*s%c %llx:%lld%s%s %s @ %dms: %s\n",

		   prefix, indent, "                ",

		   queue_status(rq),
@@ -2228,7 +2230,8 @@ void i915_request_show(struct drm_printer *m, 
		   fence_status(rq),

		   buf,

		   jiffies_to_msecs(jiffies - rq->emitted_jiffies),

		   name);

		   rcu_dereference(timeline));

	rcu_read_unlock();

}



static bool engine_match_ring(struct intel_engine_cs *engine, struct i915_request *rq)

drivers/gpu/drm/i915/i915_sw_fence.c

+8 −2
Original line number Diff line number Diff line
@@ -430,16 +430,22 @@ static void timer_i915_sw_fence_wake(struct timer_list *t) 
	struct i915_sw_dma_fence_cb_timer *cb = timer_container_of(cb, t,

								   timer);

	struct i915_sw_fence *fence;

	const char __rcu *timeline;

	const char __rcu *driver;



	fence = xchg(&cb->base.fence, NULL);

	if (!fence)

		return;



	rcu_read_lock();

	driver = dma_fence_driver_name(cb->dma);

	timeline = dma_fence_timeline_name(cb->dma);

	pr_notice("Asynchronous wait on fence %s:%s:%llx timed out (hint:%ps)\n",

		  dma_fence_driver_name(cb->dma),

		  dma_fence_timeline_name(cb->dma),

		  rcu_dereference(driver),

		  rcu_dereference(timeline),

		  cb->dma->seqno,

		  i915_sw_fence_debug_hint(fence));

	rcu_read_unlock();



	i915_sw_fence_set_error_once(fence, -ETIMEDOUT);

	i915_sw_fence_complete(fence);