[PATCH 05/40] drm/i915: Take rcu_read_lock for querying fence's driver/timeline names

[Chris Wilson]

The name very often may be freed independently of the fence, with the
only protection being RCU. To be safe as we read the names, hold RCU.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_sw_fence.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c
index 2744558f3050..dfabf291e5cd 100644
--- a/drivers/gpu/drm/i915/i915_sw_fence.c
+++ b/drivers/gpu/drm/i915/i915_sw_fence.c
@@ -430,11 +430,13 @@ static void timer_i915_sw_fence_wake(struct timer_list *t)
 	if (!fence)
 		return;
 
+	rcu_read_lock();
 	pr_notice("Asynchronous wait on fence %s:%s:%llx timed out (hint:%ps)\n",
 		  cb->dma->ops->get_driver_name(cb->dma),
 		  cb->dma->ops->get_timeline_name(cb->dma),
 		  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);
-- 
2.20.1