staging: mt7621-mmc: Check for nonzero number of scatterlist entries

The buffer descriptor setup loop is correct only if it is setting up at
least one bd struct.  Besides, there is an error if dma_map_sg() returns
0, which is possible and must be handled.

Additionally, remove the BUG_ON() checking sglen, which is unnecessary
because we configure DMA with that constraint during init.

Signed-off-by: George Hilliard <thirtythreeforty@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/mt7621-mmc/sd.c b/drivers/staging/mt7621-mmc/sd.c
index ff01872ab972f060db41aa324e310ebece3e219b..e346167754bd7799c5452cdf5f2110736839b9d4 100644 (file)
--- a/drivers/staging/mt7621-mmc/sd.c
+++ b/drivers/staging/mt7621-mmc/sd.c
@@ -591,8 +591,6 @@ static void msdc_dma_setup(struct msdc_host *host, struct msdc_dma *dma,
        struct bd *bd;
        u32 j;
 
-       BUG_ON(sglen > MAX_BD_NUM); /* not support currently */
-
        gpd = dma->gpd;
        bd  = dma->bd;
 
@@ -681,6 +679,13 @@ static int msdc_do_request(struct mmc_host *mmc, struct mmc_request *mrq)
                data->sg_count = dma_map_sg(mmc_dev(mmc), data->sg,
                                            data->sg_len,
                                            mmc_get_dma_dir(data));
+
+               if (data->sg_count == 0) {
+                       dev_err(mmc_dev(host->mmc), "failed to map DMA for transfer\n");
+                       data->error = -ENOMEM;
+                       goto done;
+               }
+
                msdc_dma_setup(host, &host->dma, data->sg,
                               data->sg_count);