[PATCH] dma-fence: Bypass signaling annotation from dma_fence_is_signaled

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

For dma_fence_is_signaled signaling critical path annotations are an
annoying cause of false positives when using dma_fence_is_signaled and
indirectly higher level helpers such as dma_resv_test_signaled etc.

Drop the critical path annotation since the "is signaled" API does not
guarantee to ever change the signaled status anyway.

We do that by adding a low level _dma_fence_signal helper and use it from
dma_fence_is_signaled.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Cc: Christian König <christian.koenig at amd.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/dma-buf/dma-fence.c | 26 ++++++++++++++++++++------
 include/linux/dma-fence.h   |  3 ++-
 2 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index f177c56269bb..ace1415f0566 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -444,6 +444,25 @@ int dma_fence_signal_locked(struct dma_fence *fence)
 }
 EXPORT_SYMBOL(dma_fence_signal_locked);
 
+/**
+ * __dma_fence_signal - signal completion of a fence bypassing critical section annotation
+ * @fence: the fence to signal
+ *
+ * This low-level helper should not be used by code external to dma-fence.h|c!
+ */
+int _dma_fence_signal(struct dma_fence *fence)
+{
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(fence->lock, flags);
+	ret = dma_fence_signal_timestamp_locked(fence, ktime_get());
+	spin_unlock_irqrestore(fence->lock, flags);
+
+	return ret;
+}
+EXPORT_SYMBOL(_dma_fence_signal);
+
 /**
  * dma_fence_signal - signal completion of a fence
  * @fence: the fence to signal
@@ -459,7 +478,6 @@ EXPORT_SYMBOL(dma_fence_signal_locked);
  */
 int dma_fence_signal(struct dma_fence *fence)
 {
-	unsigned long flags;
 	int ret;
 	bool tmp;
 
@@ -467,11 +485,7 @@ int dma_fence_signal(struct dma_fence *fence)
 		return -EINVAL;
 
 	tmp = dma_fence_begin_signalling();
-
-	spin_lock_irqsave(fence->lock, flags);
-	ret = dma_fence_signal_timestamp_locked(fence, ktime_get());
-	spin_unlock_irqrestore(fence->lock, flags);
-
+	ret = _dma_fence_signal(fence);
 	dma_fence_end_signalling(tmp);
 
 	return ret;
diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
index d54b595a0fe0..d94768ad70e4 100644
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -387,6 +387,7 @@ static inline void dma_fence_end_signalling(bool cookie) {}
 static inline void __dma_fence_might_wait(void) {}
 #endif
 
+int _dma_fence_signal(struct dma_fence *fence);
 int dma_fence_signal(struct dma_fence *fence);
 int dma_fence_signal_locked(struct dma_fence *fence);
 int dma_fence_signal_timestamp(struct dma_fence *fence, ktime_t timestamp);
@@ -452,7 +453,7 @@ dma_fence_is_signaled(struct dma_fence *fence)
 		return true;
 
 	if (fence->ops->signaled && fence->ops->signaled(fence)) {
-		dma_fence_signal(fence);
+		_dma_fence_signal(fence);
 		return true;
 	}
 
-- 
2.39.2