[PATCH] dmaengine: avoid map_cnt overflow with CONFIG_DMA_ENGINE_RAID

[Zi Yan <zi.yan@sent.com>]

From: Zi Yan <zi.yan@cs.rutgers.edu>

When CONFIG_DMA_ENGINE_RAID is enabled, unmap pool size can reach to
256. But in struct dmaengine_unmap_data, map_cnt is only u8, wrapping
to 0, if the unmap pool is maximally used. This triggers BUG() when
struct dmaengine_unmap_data is freed. Use u16 to fix the problem.

Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu>
---
 include/linux/dmaengine.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index f838764993eb..861be5cab1df 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -470,7 +470,11 @@ typedef void (*dma_async_tx_callback_result)(void *dma_async_param,
 				const struct dmaengine_result *result);
 
 struct dmaengine_unmap_data {
+#if IS_ENABLED(CONFIG_DMA_ENGINE_RAID)
+	u16 map_cnt;
+#else
 	u8 map_cnt;
+#endif
 	u8 to_cnt;
 	u8 from_cnt;
 	u8 bidi_cnt;
-- 
2.15.1