[PATCH 6/7] RFC: dma-buf: Add an extra fence to dma_resv_get_singleton_unlocked

[Jason Ekstrand]

For dma-buf sync_file import, we want to get all the fences on a
dma_resv plus one more.  We could wrap the fence we get back in an array
fence or we could make dma_resv_get_singleton_unlocked take "one more"
to make this case easier.

Signed-off-by: Jason Ekstrand <jason at jlekstrand.net>
Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Christian König <christian.koenig at amd.com>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
---
 drivers/dma-buf/dma-buf.c  |  2 +-
 drivers/dma-buf/dma-resv.c | 23 +++++++++++++++++++++--
 include/linux/dma-resv.h   |  3 ++-
 3 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 65a9574ee04ed..ea117de962903 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -389,7 +389,7 @@ static long dma_buf_export_sync_file(struct dma_buf *dmabuf,
 		return fd;
 
 	if (arg.flags & DMA_BUF_SYNC_WRITE) {
-		fence = dma_resv_get_singleton_unlocked(dmabuf->resv);
+		fence = dma_resv_get_singleton_unlocked(dmabuf->resv, NULL);
 		if (IS_ERR(fence)) {
 			ret = PTR_ERR(fence);
 			goto err_put_fd;
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 23db2181c8ad8..5a5e13a01e516 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -527,6 +527,7 @@ EXPORT_SYMBOL_GPL(dma_resv_get_fences_unlocked);
 /**
  * dma_resv_get_singleton_unlocked - get a single fence for the dma_resv object
  * @obj: the reservation object
+ * @extra: extra fence to add to the resulting array
  *
  * Get a single fence representing all unsignaled fences in the dma_resv object
  * plus the given extra fence. If we got only one fence return a new
@@ -535,7 +536,8 @@ EXPORT_SYMBOL_GPL(dma_resv_get_fences_unlocked);
  * RETURNS
  * The singleton dma_fence on success or an ERR_PTR on failure
  */
-struct dma_fence *dma_resv_get_singleton_unlocked(struct dma_resv *obj)
+struct dma_fence *dma_resv_get_singleton_unlocked(struct dma_resv *obj,
+						  struct dma_fence *extra)
 {
 	struct dma_fence *result, **resv_fences, *fence, *chain, **fences;
 	struct dma_fence_array *array;
@@ -546,7 +548,7 @@ struct dma_fence *dma_resv_get_singleton_unlocked(struct dma_resv *obj)
 	if (err)
 		return ERR_PTR(err);
 
-	if (num_resv_fences == 0)
+	if (num_resv_fences == 0 && !extra)
 		return NULL;
 
 	num_fences = 0;
@@ -562,6 +564,16 @@ struct dma_fence *dma_resv_get_singleton_unlocked(struct dma_resv *obj)
 		}
 	}
 
+	if (extra) {
+		dma_fence_deep_dive_for_each(fence, chain, j, extra) {
+			if (dma_fence_is_signaled(fence))
+				continue;
+
+			result = fence;
+			++num_fences;
+		}
+	}
+
 	if (num_fences <= 1) {
 		result = dma_fence_get(result);
 		goto put_resv_fences;
@@ -582,6 +594,13 @@ struct dma_fence *dma_resv_get_singleton_unlocked(struct dma_resv *obj)
 		}
 	}
 
+	if (extra) {
+		dma_fence_deep_dive_for_each(fence, chain, j, extra) {
+			if (dma_fence_is_signaled(fence))
+				fences[num_fences++] = dma_fence_get(fence);
+		}
+	}
+
 	if (num_fences <= 1) {
 		result = num_fences ? fences[0] : NULL;
 		kfree(fences);
diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
index c5fa09555eca5..4b1dabfa7017d 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -285,7 +285,8 @@ int dma_resv_get_fences_unlocked(struct dma_resv *obj,
 
 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
 
-struct dma_fence *dma_resv_get_singleton_unlocked(struct dma_resv *obj);
+struct dma_fence *dma_resv_get_singleton_unlocked(struct dma_resv *obj,
+						  struct dma_fence *extra);
 
 long dma_resv_wait_timeout_unlocked(struct dma_resv *obj, bool wait_all, bool intr,
 				    unsigned long timeout);
-- 
2.31.1