[PATCH] mmc: wbsd: safer check if dma_addr is valid DMA address

[Alexey Khoroshilov]

host->dma_addr can store a value that is not returned by the DMA API,
so it is safer to check if is a valid DMA address indirectly.

Signed-off-by: Alexey Khoroshilov <khoroshi...@ispras.ru>
---
 drivers/mmc/host/wbsd.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/wbsd.c b/drivers/mmc/host/wbsd.c
index 80a3b11f3217..bd04e8bae010 100644
--- a/drivers/mmc/host/wbsd.c
+++ b/drivers/mmc/host/wbsd.c
@@ -1437,11 +1437,14 @@ static void wbsd_request_dma(struct wbsd_host *host, 
int dma)
 
 static void wbsd_release_dma(struct wbsd_host *host)
 {
-       if (!dma_mapping_error(mmc_dev(host->mmc), host->dma_addr)) {
+       /*
+        * host->dma_addr is valid here iff host->dma_buffer is not NULL.
+        */
+       if (host->dma_buffer) {
                dma_unmap_single(mmc_dev(host->mmc), host->dma_addr,
                        WBSD_DMA_SIZE, DMA_BIDIRECTIONAL);
+               kfree(host->dma_buffer);
        }
-       kfree(host->dma_buffer);
        if (host->dma >= 0)
                free_dma(host->dma);
 
-- 
2.7.4