diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index 05090fb0fd5a..bd58688b81a7 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -1170,7 +1170,12 @@ const char __rcu *dma_fence_driver_name(struct dma_fence *fence) /* RCU protection is required for safe access to returned string */ ops = rcu_dereference(fence->ops); - if (ops) + + /* + * Make load ordering irrelevant by checking both signaled state and ops + * pointer and ops pointer is only set to NULL on newer implementations. + */ + if (!dma_fence_test_signaled_flag(fence) && ops) return (const char __rcu *)ops->get_driver_name(fence); else return (const char __rcu *)"detached-driver"; @@ -1203,7 +1208,12 @@ const char __rcu *dma_fence_timeline_name(struct dma_fence *fence) /* RCU protection is required for safe access to returned string */ ops = rcu_dereference(fence->ops); - if (ops) + + /* + * Make load ordering irrelevant by checking both signaled state and ops + * pointer and ops pointer is only set to NULL on newer implementations. + */ + if (!dma_fence_test_signaled_flag(fence) && ops) return (const char __rcu *)ops->get_timeline_name(fence); else return (const char __rcu *)"signaled-timeline"; diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h index 158cd609f103..ffa99b930843 100644 --- a/include/linux/dma-fence.h +++ b/include/linux/dma-fence.h @@ -141,6 +141,9 @@ struct dma_fence_ops { * compute the name at runtime, without having it to store permanently * for each fence, or build a cache of some sort. * + * The returned string is RCU protected and can be freed after the fence + * signaled and a RCU grace period passed. + * * This callback is mandatory. */ const char * (*get_driver_name)(struct dma_fence *fence); @@ -153,6 +156,9 @@ struct dma_fence_ops { * having it to store permanently for each fence, or build a cache of * some sort. * + * The returned string is RCU protected and can be freed after the fence + * signaled and a RCU grace period passed. + * * This callback is mandatory. */ const char * (*get_timeline_name)(struct dma_fence *fence);