mmc: queue: Improve error handling during allocation of bounce buffers

Allocation of previous bounce buffer in mmc_init_queue when the current
bounce buffer allocation fails was leading to a crash later in
__blk_segment_map_sg. Error handling is improved by allocating previous
bounce buffer only if the current bounce buffer allocation succeeds.
Signed-off-by: Bhuvanesh Surachari <bhuvanesh_surachari@mentor.com>
Signed-off-by: Harish Jenny K N <harish_kandiga@mentor.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/card/queue.c

@@ -232,8 +232,9 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,
 			if (!mqrq_cur->bounce_buf) {
 				pr_warn("%s: unable to allocate bounce cur buffer\n",
 					mmc_card_name(card));
-			}
-			mqrq_prev->bounce_buf = kmalloc(bouncesz, GFP_KERNEL);
+			} else {
+				mqrq_prev->bounce_buf =
+						kmalloc(bouncesz, GFP_KERNEL);
 				if (!mqrq_prev->bounce_buf) {
 					pr_warn("%s: unable to allocate bounce prev buffer\n",
 						mmc_card_name(card));
@@ -241,6 +242,7 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,
 					mqrq_cur->bounce_buf = NULL;
 				}
 			}
+		}
 
 		if (mqrq_cur->bounce_buf && mqrq_prev->bounce_buf) {
 			blk_queue_bounce_limit(mq->queue, BLK_BOUNCE_ANY);