dma-buf: generalize dma_fence unwrap & merging v3

Introduce a dma_fence_unwrap_merge() macro which allows to unwrap fences
which potentially can be containers as well and then merge them back
together into a flat dma_fence_array.

v2: rename the function, add some more comments about how the wrapper is
    used, move filtering of signaled fences into the unwrap iterator,
    add complex selftest which covers more cases.
v3: fix signaled fence filtering once more

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20220518135844.3338-5-christian.koenig@amd.com

1 files changed, 109 insertions, 0 deletions

diff --git a/drivers/dma-buf/st-dma-fence-unwrap.c b/drivers/dma-buf/st-dma-fence-unwrap.c
index e20c5a7dcfe4..4105d5ea8dde 100644
--- a/drivers/dma-buf/st-dma-fence-unwrap.c
+++ b/drivers/dma-buf/st-dma-fence-unwrap.c
@@ -238,6 +238,113 @@ static int unwrap_chain_array(void *arg)
 	return err;
 }
 
+static int unwrap_merge(void *arg)
+{
+	struct dma_fence *fence, *f1, *f2, *f3;
+	struct dma_fence_unwrap iter;
+	int err = 0;
+
+	f1 = mock_fence();
+	if (!f1)
+		return -ENOMEM;
+
+	f2 = mock_fence();
+	if (!f2) {
+		err = -ENOMEM;
+		goto error_put_f1;
+	}
+
+	f3 = dma_fence_unwrap_merge(f1, f2);
+	if (!f3) {
+		err = -ENOMEM;
+		goto error_put_f2;
+	}
+
+	dma_fence_unwrap_for_each(fence, &iter, f3) {
+		if (fence == f1) {
+			dma_fence_put(f1);
+			f1 = NULL;
+		} else if (fence == f2) {
+			dma_fence_put(f2);
+			f2 = NULL;
+		} else {
+			pr_err("Unexpected fence!\n");
+			err = -EINVAL;
+		}
+	}
+
+	if (f1 || f2) {
+		pr_err("Not all fences seen!\n");
+		err = -EINVAL;
+	}
+
+	dma_fence_put(f3);
+error_put_f2:
+	dma_fence_put(f2);
+error_put_f1:
+	dma_fence_put(f1);
+	return err;
+}
+
+static int unwrap_merge_complex(void *arg)
+{
+	struct dma_fence *fence, *f1, *f2, *f3, *f4, *f5;
+	struct dma_fence_unwrap iter;
+	int err = -ENOMEM;
+
+	f1 = mock_fence();
+	if (!f1)
+		return -ENOMEM;
+
+	f2 = mock_fence();
+	if (!f2)
+		goto error_put_f1;
+
+	f3 = dma_fence_unwrap_merge(f1, f2);
+	if (!f3)
+		goto error_put_f2;
+
+	/* The resulting array has the fences in reverse */
+	f4 = dma_fence_unwrap_merge(f2, f1);
+	if (!f4)
+		goto error_put_f3;
+
+	/* Signaled fences should be filtered, the two arrays merged. */
+	f5 = dma_fence_unwrap_merge(f3, f4, dma_fence_get_stub());
+	if (!f5)
+		goto error_put_f4;
+
+	err = 0;
+	dma_fence_unwrap_for_each(fence, &iter, f5) {
+		if (fence == f1) {
+			dma_fence_put(f1);
+			f1 = NULL;
+		} else if (fence == f2) {
+			dma_fence_put(f2);
+			f2 = NULL;
+		} else {
+			pr_err("Unexpected fence!\n");
+			err = -EINVAL;
+		}
+	}
+
+	if (f1 || f2) {
+		pr_err("Not all fences seen!\n");
+		err = -EINVAL;
+	}
+
+	dma_fence_put(f5);
+error_put_f4:
+	dma_fence_put(f4);
+error_put_f3:
+	dma_fence_put(f3);
+error_put_f2:
+	dma_fence_put(f2);
+error_put_f1:
+	dma_fence_put(f1);
+	return err;
+}
+
 int dma_fence_unwrap(void)
 {
 	static const struct subtest tests[] = {
@@ -245,6 +352,8 @@ int dma_fence_unwrap(void)
 		SUBTEST(unwrap_array),
 		SUBTEST(unwrap_chain),
 		SUBTEST(unwrap_chain_array),
+		SUBTEST(unwrap_merge),
+		SUBTEST(unwrap_merge_complex),
 	};
 
 	return subtests(tests, NULL);