dma-buf: make returning the exclusive fence optional

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.

Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180110125341.3618-1-christian.koenig@amd.com

diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c
index b759a56..461afa9 100644 (file)
--- 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 @@ unlock:
 
        *pshared_count = shared_count;
        *pshared = shared;
-       *pfence_excl = fence_excl;
+       if (pfence_excl)
+               *pfence_excl = fence_excl;
 
        return ret;
 }