[PATCH 1/2] mmc: block: Preinitialize ret in mmc_blk_issue_drv_op()

From: Geert Uytterhoeven
Date: Wed Jul 05 2017 - 05:07:37 EST

With gcc 4.1.2:

drivers/mmc/core/block.c: In function âmmc_blk_issue_drv_opâ:
drivers/mmc/core/block.c:1178: warning: âretâ may be used uninitialized in this function

Indeed, if mq_rq->ioc_count is zero, an uninitialized value will be
stored in mq_rq->drv_op_result and passed to blk_end_request_all().

Can mq_rq->ioc_count be zero?
- mmc_blk_ioctl_cmd() sets ioc_count to 1, so this is safe,
- mmc_blk_ioctl_multi_cmd() obtains ioc_count from user space in
response to the MMC_IOC_MULTI_CMD ioctl, and does allow zero.

Preinitialize ret to -EINVAL to fix this for current and future callers.

Fixes: 0493f6fe5bdee8ac ("mmc: block: Move boot partition locking into a driver op")
Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
I assume -EINVAL is the error we want to return here if ioc_count is
Or should it return success (zero), like mmc_blk_ioctl_multi_cmd() used
to do?
drivers/mmc/core/block.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index 0cfac2d391073922..9472e89af3efa37e 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -1175,7 +1175,7 @@ static void mmc_blk_issue_drv_op(struct mmc_queue *mq, struct request *req)
struct mmc_queue_req *mq_rq;
struct mmc_card *card = mq->card;
struct mmc_blk_data *md = mq->blkdata;
- int ret;
+ int ret = -EINVAL;
int i;

mq_rq = req_to_mmc_queue_req(req);
@@ -1206,7 +1206,6 @@ static void mmc_blk_issue_drv_op(struct mmc_queue *mq, struct request *req)
pr_err("%s: unknown driver specific operation\n",
- ret = -EINVAL;
mq_rq->drv_op_result = ret;