dma-buf: return index of the first signaled fence (v2)

Return the index of the first signaled fence.  This information
is useful in some APIs like Vulkan.

v2: rebase on drm-next (fence -> dma_fence)
Signed-off-by: monk.liu <monk.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
 [sumits: fix warnings]
Link: http://patchwork.freedesktop.org/patch/msgid/1478290570-30982-1-git-send-email-alexander.deucher@amd.com

drivers/dma-buf/dma-fence.c

@@ -403,14 +403,18 @@ dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout)
 EXPORT_SYMBOL(dma_fence_default_wait);
 
 static bool
-dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count)
+dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count,
+			    uint32_t *idx)
 {
 	int i;
 
 	for (i = 0; i < count; ++i) {
 		struct dma_fence *fence = fences[i];
-		if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+		if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
+			if (idx)
+				*idx = i;
 			return true;
+		}
 	}
 	return false;
 }
@@ -422,6 +426,8 @@ dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count)
  * @count:	[in]	number of fences to wait on
  * @intr:	[in]	if true, do an interruptible wait
  * @timeout:	[in]	timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
+ * @idx:       [out]	the first signaled fence index, meaningful only on
+ *			positive return
  *
  * Returns -EINVAL on custom fence wait implementation, -ERESTARTSYS if
  * interrupted, 0 if the wait timed out, or the remaining timeout in jiffies
@@ -433,7 +439,7 @@ dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count)
  */
 signed long
 dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
-			   bool intr, signed long timeout)
+			   bool intr, signed long timeout, uint32_t *idx)
 {
 	struct default_wait_cb *cb;
 	signed long ret = timeout;
@@ -444,8 +450,11 @@ dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
 
 	if (timeout == 0) {
 		for (i = 0; i < count; ++i)
-			if (dma_fence_is_signaled(fences[i]))
+			if (dma_fence_is_signaled(fences[i])) {
+				if (idx)
+					*idx = i;
 				return 1;
+			}
 
 		return 0;
 	}
@@ -468,6 +477,8 @@ dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
 		if (dma_fence_add_callback(fence, &cb[i].base,
 					   dma_fence_default_wait_cb)) {
 			/* This fence is already signaled */
+			if (idx)
+				*idx = i;
 			goto fence_rm_cb;
 		}
 	}
@@ -478,7 +489,7 @@ dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
 		else
 			set_current_state(TASK_UNINTERRUPTIBLE);
 
-		if (dma_fence_test_signaled_any(fences, count))
+		if (dma_fence_test_signaled_any(fences, count, idx))
 			break;
 
 		ret = schedule_timeout(ret);

include/linux/dma-fence.h

@@ -382,7 +382,8 @@ signed long dma_fence_wait_timeout(struct dma_fence *,
 				   bool intr, signed long timeout);
 signed long dma_fence_wait_any_timeout(struct dma_fence **fences,
 				       uint32_t count,
-				       bool intr, signed long timeout);
+				       bool intr, signed long timeout,
+				       uint32_t *idx);
 
 /**
  * dma_fence_wait - sleep until the fence gets signaled