[PATCH 18/17] mmc: sdhci: further fix for DMA unmapping in sdhci_post_req()

[Russell King <rmk+kernel@arm.linux.org.uk>]

sdhci_post_req() exists to unmap a previously mapped but already
finished request, while the next request is in progress.  However, the
state of the SDHCI_REQ_USE_DMA flag depends on the last submitted
request.

This means we can end up clearing the flag due to a quirk, which then
means that sdhci_post_req() fails to unmap the DMA buffer, potentially
leading to data corruption.

We can safely ignore the SDHCI_REQ_USE_DMA here, as testing
data->host_cookie is entirely sufficient.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
This is another fairly important bug fix.

 drivers/mmc/host/sdhci.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index df72d1eb54a4..f877a092c6bc 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -2053,13 +2053,12 @@ static void sdhci_post_req(struct mmc_host *mmc, struct mmc_request *mrq,
 	struct sdhci_host *host = mmc_priv(mmc);
 	struct mmc_data *data = mrq->data;
 
-	if (host->flags & SDHCI_REQ_USE_DMA) {
-		if (data->host_cookie != COOKIE_UNMAPPED)
-			dma_unmap_sg(mmc_dev(host->mmc), data->sg, data->sg_len,
-					 data->flags & MMC_DATA_WRITE ?
-					 DMA_TO_DEVICE : DMA_FROM_DEVICE);
-		data->host_cookie = COOKIE_UNMAPPED;
-	}
+	if (data->host_cookie != COOKIE_UNMAPPED)
+		dma_unmap_sg(mmc_dev(host->mmc), data->sg, data->sg_len,
+			     data->flags & MMC_DATA_WRITE ?
+			       DMA_TO_DEVICE : DMA_FROM_DEVICE);
+
+	data->host_cookie = COOKIE_UNMAPPED;
 }
 
 static void sdhci_pre_req(struct mmc_host *mmc, struct mmc_request *mrq,
-- 
2.1.0