linux-kernel - [PATCH 03/11] dma-buf/fence: add signal_on

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Message-Id: <1464786612-5010-4-git-send-email-deathsimple@vodafone.de>
Date:	Wed,  1 Jun 2016 15:10:04 +0200
From:	Christian König <deathsimple@...afone.de>
To:	dri-devel@...ts.freedesktop.org
Cc:	linux-kernel@...r.kernel.org, daniel@...ll.ch,
	chris@...is-wilson.co.uk, gustavo@...ovan.org
Subject: [PATCH 03/11] dma-buf/fence: add signal_on_any to the fence array v2

From: Christian König <christian.koenig@....com>

If @signal_on_any is true the fence array signals if any fence in the array
signals, otherwise it signals when all fences in the array signal.

v2: fix signaled test and add comment suggested by Chris Wilson.

Signed-off-by: Christian König <christian.koenig@....com>
---
 drivers/dma-buf/fence-array.c | 33 +++++++++++++++++++++++++--------
 include/linux/fence-array.h   |  3 ++-
 2 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/drivers/dma-buf/fence-array.c b/drivers/dma-buf/fence-array.c
index 8141217..a8731c8 100644
--- a/drivers/dma-buf/fence-array.c
+++ b/drivers/dma-buf/fence-array.c
@@ -41,6 +41,7 @@ static void fence_array_cb_func(struct fence *f, struct fence_cb *cb)
 
 	if (atomic_dec_and_test(&array->num_pending))
 		fence_signal(&array->base);
+	fence_put(&array->base);
 }
 
 static bool fence_array_enable_signaling(struct fence *fence)
@@ -51,10 +52,21 @@ static bool fence_array_enable_signaling(struct fence *fence)
 
 	for (i = 0; i < array->num_fences; ++i) {
 		cb[i].array = array;
+		/*
+		 * As we may report that the fence is signaled before all
+		 * callbacks are complete, we need to take an additional
+		 * reference count on the array so that we do not free it too
+		 * early. The core fence handling will only hold the reference
+		 * until we signal the array as complete (but that is now
+		 * insufficient).
+		 */
+		fence_get(&array->base);
 		if (fence_add_callback(array->fences[i], &cb[i].cb,
-				       fence_array_cb_func))
+				       fence_array_cb_func)) {
+			fence_put(&array->base);
 			if (atomic_dec_and_test(&array->num_pending))
 				return false;
+		}
 	}
 
 	return true;
@@ -64,7 +76,7 @@ static bool fence_array_signaled(struct fence *fence)
 {
 	struct fence_array *array = to_fence_array(fence);
 
-	return atomic_read(&array->num_pending) == 0;
+	return atomic_read(&array->num_pending) <= 0;
 }
 
 static void fence_array_release(struct fence *fence)
@@ -90,10 +102,11 @@ const struct fence_ops fence_array_ops = {
 
 /**
  * fence_array_create - Create a custom fence array
- * @num_fences:	[in]	number of fences to add in the array
- * @fences:	[in]	array containing the fences
- * @context:	[in]	fence context to use
- * @seqno:	[in]	sequence number to use
+ * @num_fences:		[in]	number of fences to add in the array
+ * @fences:		[in]	array containing the fences
+ * @context:		[in]	fence context to use
+ * @seqno:		[in]	sequence number to use
+ * @signal_on_any	[in]	signal on any fence in the array
  *
  * Allocate a fence_array object and initialize the base fence with fence_init().
  * In case of error it returns NULL.
@@ -101,9 +114,13 @@ const struct fence_ops fence_array_ops = {
  * The caller should allocte the fences array with num_fences size
  * and fill it with the fences it wants to add to the object. Ownership of this
  * array is take and fence_put() is used on each fence on release.
+ *
+ * If @signal_on_any is true the fence array signals if any fence in the array
+ * signals, otherwise it signals when all fences in the array signal.
  */
 struct fence_array *fence_array_create(int num_fences, struct fence **fences,
-				       u64 context, unsigned seqno)
+				       u64 context, unsigned seqno,
+				       bool signal_on_any)
 {
 	struct fence_array *array;
 	size_t size = sizeof(*array);
@@ -119,7 +136,7 @@ struct fence_array *fence_array_create(int num_fences, struct fence **fences,
 		   context, seqno);
 
 	array->num_fences = num_fences;
-	atomic_set(&array->num_pending, num_fences);
+	atomic_set(&array->num_pending, signal_on_any ? 1 : num_fences);
 	array->fences = fences;
 
 	return array;
diff --git a/include/linux/fence-array.h b/include/linux/fence-array.h
index 593ab98..86baaa4 100644
--- a/include/linux/fence-array.h
+++ b/include/linux/fence-array.h
@@ -67,6 +67,7 @@ static inline struct fence_array *to_fence_array(struct fence *fence)
 }
 
 struct fence_array *fence_array_create(int num_fences, struct fence **fences,
-				       u64 context, unsigned seqno);
+				       u64 context, unsigned seqno,
+				       bool signal_on_any);
 
 #endif /* __LINUX_FENCE_ARRAY_H */
-- 
2.5.0