[RFC 13/14] dma-fence: Add helper for custom fence context when merging fences

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursulin at igalia.com>

Add a dma_fence_unwrap_merge_context() helper which works exactly the same
as the existing dma_fence_unwrap_merge() apart that instead of always
allocating a new fence context it allows the caller to specify it.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at igalia.com>
Cc: Christian König <christian.koenig at amd.com>
Cc: Danilo Krummrich <dakr at redhat.com>
Cc: Matthew Brost <matthew.brost at intel.com>
Cc: Philipp Stanner <pstanner at redhat.com>
---
 drivers/dma-buf/dma-fence-unwrap.c |  8 ++++----
 include/linux/dma-fence-unwrap.h   | 31 ++++++++++++++++++++++++++++--
 2 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/drivers/dma-buf/dma-fence-unwrap.c b/drivers/dma-buf/dma-fence-unwrap.c
index 2a059ac0ed27..fd9813a50532 100644
--- a/drivers/dma-buf/dma-fence-unwrap.c
+++ b/drivers/dma-buf/dma-fence-unwrap.c
@@ -80,7 +80,8 @@ static int fence_cmp(const void *_a, const void *_b)
 }
 
 /* Implementation for the dma_fence_merge() marco, don't use directly */
-struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences,
+struct dma_fence *__dma_fence_unwrap_merge(u64 context,
+					   unsigned int num_fences,
 					   struct dma_fence **fences,
 					   struct dma_fence_unwrap *iter)
 {
@@ -156,9 +157,8 @@ struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences,
 	count = ++j;
 
 	if (count > 1) {
-		result = dma_fence_array_create(count, array,
-						dma_fence_context_alloc(1),
-						1, false);
+		result = dma_fence_array_create(count, array, context, 1,
+						false);
 		if (!result) {
 			for (i = 0; i < count; i++)
 				dma_fence_put(array[i]);
diff --git a/include/linux/dma-fence-unwrap.h b/include/linux/dma-fence-unwrap.h
index 66b1e56fbb81..12e8c43848ce 100644
--- a/include/linux/dma-fence-unwrap.h
+++ b/include/linux/dma-fence-unwrap.h
@@ -8,6 +8,8 @@
 #ifndef __LINUX_DMA_FENCE_UNWRAP_H
 #define __LINUX_DMA_FENCE_UNWRAP_H
 
+#include <linux/types.h>
+
 struct dma_fence;
 
 /**
@@ -48,7 +50,8 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor);
 	for (fence = dma_fence_unwrap_first(head, cursor); fence;	\
 	     fence = dma_fence_unwrap_next(cursor))
 
-struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences,
+struct dma_fence *__dma_fence_unwrap_merge(u64 context,
+					   unsigned int num_fences,
 					   struct dma_fence **fences,
 					   struct dma_fence_unwrap *cursors);
 
@@ -69,7 +72,31 @@ struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences,
 		struct dma_fence *__f[] = { __VA_ARGS__ };		\
 		struct dma_fence_unwrap __c[ARRAY_SIZE(__f)];		\
 									\
-		__dma_fence_unwrap_merge(ARRAY_SIZE(__f), __f, __c);	\
+		__dma_fence_unwrap_merge(dma_fence_context_alloc(1),	\
+					 ARRAY_SIZE(__f), __f, __c);	\
+	})
+
+/**
+ * dma_fence_unwrap_merge_context - unwrap and merge fences with context
+ *
+ * All fences given as parameters are unwrapped and merged back together as flat
+ * dma_fence_array. Useful if multiple containers need to be merged together.
+ *
+ * Implemented as a macro to allocate the necessary arrays on the stack and
+ * account the stack frame size to the caller.
+ *
+ * Fence context is passed in and not automatically allocated.
+ *
+ * Returns NULL on memory allocation failure, a dma_fence object representing
+ * all the given fences otherwise.
+ */
+#define dma_fence_unwrap_merge_context(context, ...)					\
+	({								\
+		struct dma_fence *__f[] = { __VA_ARGS__ };		\
+		struct dma_fence_unwrap __c[ARRAY_SIZE(__f)];		\
+									\
+		__dma_fence_unwrap_merge((context),			\
+					 ARRAY_SIZE(__f), __f, __c);	\
 	})
 
 #endif
-- 
2.47.1