New subject: [Linaro-mm-sig] [PATCH] dma-buf: make returning the exclusive fence optional

10 Jan 2018

Change reservation_object_get_fences_rcu to make the exclusive fence
pointer optional.
If not specified the exclusive fence is put into the fence array as
well.
This is helpful for a couple of cases where we need all fences in a
single array.
Signed-off-by: Christian König christian.koenig@amd.com
---
 drivers/dma-buf/reservation.c | 31 ++++++++++++++++++++++---------
 1 file changed, 22 insertions(+), 9 deletions(-)

diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c
index b759a569b7b8..461afa9febd4 100644
--- a/drivers/dma-buf/reservation.c
+++ b/drivers/dma-buf/reservation.c
@@ -374,8 +374,9 @@ EXPORT_SYMBOL(reservation_object_copy_fences);
  * @pshared: the array of shared fence ptrs returned (array is krealloc'd to
  * the required size, and must be freed by caller)
  *
- * RETURNS
- * Zero or -errno
+ * Retrieve all fences from the reservation object. If the pointer for the
+ * exclusive fence is not specified the fence is put into the array of the
+ * shared fences as well. Returns either zero or -ENOMEM.
  */
 int reservation_object_get_fences_rcu(struct reservation_object *obj,
    			      struct dma_fence **pfence_excl,
@@ -389,8 +390,8 @@ int reservation_object_get_fences_rcu(struct reservation_object *obj,
do {
    	struct reservation_object_list *fobj;
-		unsigned seq;
-		unsigned int i;
+		unsigned int i, seq;
+		size_t sz = 0;
shared_count = i = 0;
@@ -402,9 +403,14 @@ int reservation_object_get_fences_rcu(struct reservation_object *obj,
    		goto unlock;
fobj = rcu_dereference(obj->fence);
-		if (fobj) {
+		if (fobj)
+			sz += sizeof(*shared) * fobj->shared_max;
+
+		if (!pfence_excl && fence_excl)
+			sz += sizeof(*shared);
+
+		if (sz) {
    		struct dma_fence **nshared;
-			size_t sz = sizeof(*shared) * fobj->shared_max;
nshared = krealloc(shared, sz,
    				   GFP_NOWAIT | __GFP_NOWARN);
@@ -420,13 +426,19 @@ int reservation_object_get_fences_rcu(struct reservation_object *obj,
    			break;
    		}
    		shared = nshared;
-			shared_count = fobj->shared_count;
-
+			shared_count = fobj ? fobj->shared_count : 0;
    		for (i = 0; i < shared_count; ++i) {
    			shared[i] = rcu_dereference(fobj->shared[i]);
    			if (!dma_fence_get_rcu(shared[i]))
    				break;
    		}
+
+			if (!pfence_excl && fence_excl) {
+				shared[i] = fence_excl;
+				fence_excl = NULL;
+				++i;
+				++shared_count;
+			}
    	}
if (i != shared_count || read_seqcount_retry(&obj->seq, seq)) {
@@ -448,7 +460,8 @@ int reservation_object_get_fences_rcu(struct reservation_object *obj,
*pshared_count = shared_count;
    *pshared = shared;
-	*pfence_excl = fence_excl;
+	if (pfence_excl)
+		*pfence_excl = fence_excl;
return ret;
 }
-- 
2.14.1


    