4 files changed, 44 insertions, 20 deletions

diff --git a/drivers/dma-buf/dma-fence-unwrap.c b/drivers/dma-buf/dma-fence-unwrap.c
index 7002bca792ff..c625bb2b5d56 100644
--- a/drivers/dma-buf/dma-fence-unwrap.c
+++ b/drivers/dma-buf/dma-fence-unwrap.c
@@ -66,18 +66,36 @@ struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences,
 {
 	struct dma_fence_array *result;
 	struct dma_fence *tmp, **array;
+	ktime_t timestamp;
 	unsigned int i;
 	size_t count;
 
 	count = 0;
+	timestamp = ns_to_ktime(0);
 	for (i = 0; i < num_fences; ++i) {
-		dma_fence_unwrap_for_each(tmp, &iter[i], fences[i])
-			if (!dma_fence_is_signaled(tmp))
+		dma_fence_unwrap_for_each(tmp, &iter[i], fences[i]) {
+			if (!dma_fence_is_signaled(tmp)) {
 				++count;
+			} else if (test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT,
+					    &tmp->flags)) {
+				if (ktime_after(tmp->timestamp, timestamp))
+					timestamp = tmp->timestamp;
+			} else {
+				/*
+				 * Use the current time if the fence is
+				 * currently signaling.
+				 */
+				timestamp = ktime_get();
+			}
+		}
 	}
 
+	/*
+	 * If we couldn't find a pending fence just return a private signaled
+	 * fence with the timestamp of the last signaled one.
+	 */
 	if (count == 0)
-		return dma_fence_get_stub();
+		return dma_fence_allocate_private_stub(timestamp);
 
 	array = kmalloc_array(count, sizeof(*array), GFP_KERNEL);
 	if (!array)
@@ -138,7 +156,7 @@ restart:
 	} while (tmp);
 
 	if (count == 0) {
-		tmp = dma_fence_get_stub();
+		tmp = dma_fence_allocate_private_stub(ktime_get());
 		goto return_tmp;
 	}
 
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index f177c56269bb..8aa8f8cb7071 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -150,16 +150,17 @@ EXPORT_SYMBOL(dma_fence_get_stub);
 
 /**
  * dma_fence_allocate_private_stub - return a private, signaled fence
+ * @timestamp: timestamp when the fence was signaled
  *
  * Return a newly allocated and signaled stub fence.
  */
-struct dma_fence *dma_fence_allocate_private_stub(void)
+struct dma_fence *dma_fence_allocate_private_stub(ktime_t timestamp)
 {
 	struct dma_fence *fence;
 
 	fence = kzalloc(sizeof(*fence), GFP_KERNEL);
 	if (fence == NULL)
-		return ERR_PTR(-ENOMEM);
+		return NULL;
 
 	dma_fence_init(fence,
 		       &dma_fence_stub_ops,
@@ -169,7 +170,7 @@ struct dma_fence *dma_fence_allocate_private_stub(void)
 	set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 		&fence->flags);
 
-	dma_fence_signal(fence);
+	dma_fence_signal_timestamp(fence, timestamp);
 
 	return fence;
 }
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index b6f71eb00866..38b4110378de 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -571,6 +571,7 @@ int dma_resv_get_fences(struct dma_resv *obj, enum dma_resv_usage usage,
 	dma_resv_for_each_fence_unlocked(&cursor, fence) {
 
 		if (dma_resv_iter_is_restarted(&cursor)) {
+			struct dma_fence **new_fences;
 			unsigned int count;
 
 			while (*num_fences)
@@ -579,13 +580,17 @@ int dma_resv_get_fences(struct dma_resv *obj, enum dma_resv_usage usage,
 			count = cursor.num_fences + 1;
 
 			/* Eventually re-allocate the array */
-			*fences = krealloc_array(*fences, count,
-						 sizeof(void *),
-						 GFP_KERNEL);
-			if (count && !*fences) {
+			new_fences = krealloc_array(*fences, count,
+						    sizeof(void *),
+						    GFP_KERNEL);
+			if (count && !new_fences) {
+				kfree(*fences);
+				*fences = NULL;
+				*num_fences = 0;
 				dma_resv_iter_end(&cursor);
 				return -ENOMEM;
 			}
+			*fences = new_fences;
 		}
 
 		(*fences)[(*num_fences)++] = dma_fence_get(fence);
diff --git a/drivers/dma-buf/sw_sync.c b/drivers/dma-buf/sw_sync.c
index 63f0aeb66db6..f0a35277fd84 100644
--- a/drivers/dma-buf/sw_sync.c
+++ b/drivers/dma-buf/sw_sync.c
@@ -191,6 +191,7 @@ static const struct dma_fence_ops timeline_fence_ops = {
  */
 static void sync_timeline_signal(struct sync_timeline *obj, unsigned int inc)
 {
+	LIST_HEAD(signalled);
 	struct sync_pt *pt, *next;
 
 	trace_sync_timeline(obj);
@@ -203,21 +204,20 @@ static void sync_timeline_signal(struct sync_timeline *obj, unsigned int inc)
 		if (!timeline_fence_signaled(&pt->base))
 			break;
 
-		list_del_init(&pt->link);
+		dma_fence_get(&pt->base);
+
+		list_move_tail(&pt->link, &signalled);
 		rb_erase(&pt->node, &obj->pt_tree);
 
-		/*
-		 * A signal callback may release the last reference to this
-		 * fence, causing it to be freed. That operation has to be
-		 * last to avoid a use after free inside this loop, and must
-		 * be after we remove the fence from the timeline in order to
-		 * prevent deadlocking on timeline->lock inside
-		 * timeline_fence_release().
-		 */
 		dma_fence_signal_locked(&pt->base);
 	}
 
 	spin_unlock_irq(&obj->lock);
+
+	list_for_each_entry_safe(pt, next, &signalled, link) {
+		list_del_init(&pt->link);
+		dma_fence_put(&pt->base);
+	}
 }
 
 /**