drm/msm: for array in-fences, check if all backing fences are from our own context before waiting

Use the dma_fence_match_context helper to check if all backing fences
are from our own context, in which case we don't have to wait.
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Gustavo Padovan <gustavo.padovan@collabora.com>
[rebased on code-motion]
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/msm_gem_submit.c

@@ -410,12 +410,11 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
 		if (!in_fence)
 			return -EINVAL;
 
-		/* TODO if we get an array-fence due to userspace merging multiple
-		 * fences, we need a way to determine if all the backing fences
-		 * are from our own context..
+		/*
+		 * Wait if the fence is from a foreign context, or if the fence
+		 * array contains any fence from a foreign context.
 		 */
-
-		if (in_fence->context != gpu->fctx->context) {
+		if (!dma_fence_match_context(in_fence, gpu->fctx->context)) {
 			ret = dma_fence_wait(in_fence, true);
 			if (ret)
 				return ret;