dma-fence: add dma_fence_match_context helper

Add a helper to check if all fences in a fence array are from a given
context. For convenience, the function can also handle being given a
non-array fence.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.com>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1489768492-25190-1-git-send-email-p.zabel@pengutronix.de
diff --git a/include/linux/dma-fence-array.h b/include/linux/dma-fence-array.h
index 5900945..332a542 100644
--- a/include/linux/dma-fence-array.h
+++ b/include/linux/dma-fence-array.h
@@ -83,4 +83,6 @@ struct dma_fence_array *dma_fence_array_create(int num_fences,
 					       u64 context, unsigned seqno,
 					       bool signal_on_any);
 
+bool dma_fence_match_context(struct dma_fence *fence, u64 context);
+
 #endif /* __LINUX_DMA_FENCE_ARRAY_H */