[PATCH 2/2] dma-buf/fence-array: hold fences reference when creating an array

[Gustavo Padovan]

From: Gustavo Padovan <gustavo.padovan at collabora.co.uk>

When creating fence arrays we were not holding references to the fences
in the array, however when destroy the array we were putting away a
reference to these fences.

This patch hold the ref for all fences in the array when creating the
array.

It then removes the code that was holding the fences on both amdgpu_vm and
sync_file. For sync_file, specially, we worked on small referencing
refactor for sync_file_merge().

Signed-off-by: Gustavo Padovan <gustavo.padovan at collabora.co.uk>
---
 drivers/dma-buf/fence-array.c          |  8 ++++----
 drivers/dma-buf/sync_file.c            | 14 +++-----------
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c |  3 ---
 3 files changed, 7 insertions(+), 18 deletions(-)

diff --git a/drivers/dma-buf/fence-array.c b/drivers/dma-buf/fence-array.c
index f1989fc..598737f 100644
--- a/drivers/dma-buf/fence-array.c
+++ b/drivers/dma-buf/fence-array.c
@@ -112,10 +112,6 @@ EXPORT_SYMBOL(fence_array_ops);
  * Allocate a fence_array object and initialize the base fence with fence_init().
  * In case of error it returns NULL.
  *
- * The caller should allocate 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 taken 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.
  */
@@ -125,6 +121,7 @@ struct fence_array *fence_array_create(int num_fences, struct fence **fences,
 {
 	struct fence_array *array;
 	size_t size = sizeof(*array);
+	int i;
 
 	/* Allocate the callback structures behind the array. */
 	size += num_fences * sizeof(struct fence_array_cb);
@@ -140,6 +137,9 @@ struct fence_array *fence_array_create(int num_fences, struct fence **fences,
 	atomic_set(&array->num_pending, signal_on_any ? 1 : num_fences);
 	array->fences = fences;
 
+	for (i = 0; i < array->num_fences; ++i)
+		fence_get(array->fences[i]);
+
 	return array;
 }
 EXPORT_SYMBOL(fence_array_create);
diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
index 235f8ac..678baaf 100644
--- a/drivers/dma-buf/sync_file.c
+++ b/drivers/dma-buf/sync_file.c
@@ -142,14 +142,8 @@ static int sync_file_set_fence(struct sync_file *sync_file,
 {
 	struct fence_array *array;
 
-	/*
-	 * The reference for the fences in the new sync_file and held
-	 * in add_fence() during the merge procedure, so for num_fences == 1
-	 * we already own a new reference to the fence. For num_fence > 1
-	 * we own the reference of the fence_array creation.
-	 */
 	if (num_fences == 1) {
-		sync_file->fence = fences[0];
+		sync_file->fence = fence_get(fences[0]);
 		kfree(fences);
 	} else {
 		array = fence_array_create(num_fences, fences,
@@ -180,10 +174,8 @@ static void add_fence(struct fence **fences, int *i, struct fence *fence)
 {
 	fences[*i] = fence;
 
-	if (!fence_is_signaled(fence)) {
-		fence_get(fence);
+	if (!fence_is_signaled(fence))
 		(*i)++;
-	}
 }
 
 /**
@@ -255,7 +247,7 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
 		add_fence(fences, &i, b_fences[i_b]);
 
 	if (i == 0)
-		fences[i++] = fence_get(a_fences[0]);
+		fences[i++] = a_fences[0];
 
 	if (num_fences > i) {
 		nfences = krealloc(fences, i * sizeof(*fences),
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index bc4b22c..4ee7988 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -228,9 +228,6 @@ int amdgpu_vm_grab_id(struct amdgpu_vm *vm, struct amdgpu_ring *ring,
 		struct fence_array *array;
 		unsigned j;
 
-		for (j = 0; j < i; ++j)
-			fence_get(fences[j]);
-
 		array = fence_array_create(i, fences, fence_context,
 					   seqno, true);
 		if (!array) {
-- 
2.5.5