[RFC v2 12/13] drm/i915: Protect access to driver and timeline name

[Tvrtko Ursulin]

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

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at igalia.com>
---
 drivers/gpu/drm/i915/gt/intel_gt_requests.c | 2 ++
 drivers/gpu/drm/i915/i915_request.c         | 5 +++--
 drivers/gpu/drm/i915/i915_sw_fence.c        | 2 ++
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_gt_requests.c b/drivers/gpu/drm/i915/gt/intel_gt_requests.c
index ae3557ed6c1e..11fca24c8b5b 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_requests.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_requests.c
@@ -251,10 +251,12 @@ void intel_gt_watchdog_work(struct work_struct *work)
 		if (!i915_request_completed(rq)) {
 			struct dma_fence *f = &rq->fence;
 
+			dma_fence_access_begin();
 			pr_notice("Fence expiration time out i915-%s:%s:%llx!\n",
 				  dma_fence_driver_name(f),
 				  dma_fence_timeline_name(f),
 				  f->seqno);
+			dma_fence_access_end();
 			i915_request_cancel(rq, -EINTR);
 		}
 		i915_request_put(rq);
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 4874c4f1e4ab..8008b7767641 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -2184,7 +2184,6 @@ 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);
 	char buf[80] = "";
 	int x = 0;
 
@@ -2220,6 +2219,7 @@ void i915_request_show(struct drm_printer *m,
 
 	x = print_sched_attr(&rq->sched.attr, buf, x, sizeof(buf));
 
+	dma_fence_access_begin();
 	drm_printf(m, "%s%.*s%c %llx:%lld%s%s %s @ %dms: %s\n",
 		   prefix, indent, "                ",
 		   queue_status(rq),
@@ -2228,7 +2228,8 @@ void i915_request_show(struct drm_printer *m,
 		   fence_status(rq),
 		   buf,
 		   jiffies_to_msecs(jiffies - rq->emitted_jiffies),
-		   name);
+		   dma_fence_timeline_name((struct dma_fence *)&rq->fence));
+	dma_fence_access_end();
 }
 
 static bool engine_match_ring(struct intel_engine_cs *engine, struct i915_request *rq)
diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c
index e51ca7e50a4e..e7bdc1165b90 100644
--- a/drivers/gpu/drm/i915/i915_sw_fence.c
+++ b/drivers/gpu/drm/i915/i915_sw_fence.c
@@ -434,11 +434,13 @@ static void timer_i915_sw_fence_wake(struct timer_list *t)
 	if (!fence)
 		return;
 
+	dma_fence_access_begin();
 	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),
 		  cb->dma->seqno,
 		  i915_sw_fence_debug_hint(fence));
+	dma_fence_access_end();
 
 	i915_sw_fence_set_error_once(fence, -ETIMEDOUT);
 	i915_sw_fence_complete(fence);
-- 
2.48.0