[PATCH 1/2] dma-buf/dma-fence: Trim dma_fence_add_callback()

[Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>]

Rearrange the code to pull the operations beore the fence->lock critical
section, and remove a small amount of redundancy:

Function                                     old     new   delta
dma_fence_add_callback                       156     145     -11

Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
 drivers/dma-buf/dma-fence.c | 26 +++++++++++---------------
 1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index 656e9ac2d028..8d5bdfce638e 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -348,29 +348,25 @@ EXPORT_SYMBOL(dma_fence_enable_sw_signaling);
 int dma_fence_add_callback(struct dma_fence *fence, struct dma_fence_cb *cb,
 			   dma_fence_func_t func)
 {
-	unsigned long flags;
-	int ret = 0;
+	int ret = -ENOENT;
 
 	if (WARN_ON(!fence || !func))
 		return -EINVAL;
 
-	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
-		INIT_LIST_HEAD(&cb->node);
-		return -ENOENT;
-	}
+	cb->func = func;
+	INIT_LIST_HEAD(&cb->node);
 
-	spin_lock_irqsave(fence->lock, flags);
+	if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
+		unsigned long flags;
 
-	if (__dma_fence_enable_signaling(fence)) {
-		cb->func = func;
-		list_add_tail(&cb->node, &fence->cb_list);
-	} else {
-		INIT_LIST_HEAD(&cb->node);
-		ret = -ENOENT;
+		spin_lock_irqsave(fence->lock, flags);
+		if (__dma_fence_enable_signaling(fence)) {
+			list_add_tail(&cb->node, &fence->cb_list);
+			ret = 0;
+		}
+		spin_unlock_irqrestore(fence->lock, flags);
 	}
 
-	spin_unlock_irqrestore(fence->lock, flags);
-
 	return ret;
 }
 EXPORT_SYMBOL(dma_fence_add_callback);
-- 
2.20.1

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