[PATCHv5 1/2] mmc: block: Remove error check of hw_reset on reset

["Christian Löhle" <CLoehle@hyperstone.com>]

Before switching back to the right partition in mmc_blk_reset there used
to be a check if hw_reset was even supported. This return value
was removed, so there is no reason to check. Furthermore ensure
part_curr is not falsely set to a valid value on reset or
partition switch error.

As part of this change the code paths of mmc_blk_reset calls were checked
to ensure no commands are issued after a failed mmc_blk_reset directly
without going through the block layer.

Fixes: fefdd3c91e0a ("mmc: core: Drop superfluous validations in mmc_hw|sw_reset()")
Cc: stable@vger.kernel.org

Signed-off-by: Christian Loehle <cloehle@hyperstone.com>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
---
-v5: Remove nested if
-v4: Only partition switch if necessary and fix one mmc_blk_reset call
-v3: Ensure invalid part_curr on error
-v2: Do not attempt to switch partitions if reset failed

 drivers/mmc/core/block.c | 44 ++++++++++++++++++++++++----------------
 1 file changed, 26 insertions(+), 18 deletions(-)

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index ce89611a136e..0be7ab6ce1c8 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -134,6 +134,7 @@ struct mmc_blk_data {
 	 * track of the current selected device partition.
 	 */
 	unsigned int	part_curr;
+#define MMC_BLK_PART_INVALID	UINT_MAX	/* Unknown partition active */
 	int	area_type;
 
 	/* debugfs files (only in main mmc_blk_data) */
@@ -987,33 +988,39 @@ static unsigned int mmc_blk_data_timeout_ms(struct mmc_host *host,
 	return ms;
 }
 
+/*
+ * Attempts to reset the card and get back to the requested partition.
+ * Therefore any error here must result in cancelling the block layer
+ * request, it must not be reattempted without going through the mmc_blk
+ * partition sanity checks.
+ */
 static int mmc_blk_reset(struct mmc_blk_data *md, struct mmc_host *host,
 			 int type)
 {
 	int err;
+	struct mmc_blk_data *main_md = dev_get_drvdata(&host->card->dev);
 
 	if (md->reset_done & type)
 		return -EEXIST;
 
 	md->reset_done |= type;
 	err = mmc_hw_reset(host->card);
+	/*
+	 * A successful reset will leave the card in the main partition, but
+	 * upon failure it might not be, so set it to MMC_BLK_PART_INVALID
+	 * in that case.
+	 */
+	main_md->part_curr = err ? MMC_BLK_PART_INVALID : main_md->part_type;
+	if (err)
+		return err;
 	/* Ensure we switch back to the correct partition */
-	if (err) {
-		struct mmc_blk_data *main_md =
-			dev_get_drvdata(&host->card->dev);
-		int part_err;
-
-		main_md->part_curr = main_md->part_type;
-		part_err = mmc_blk_part_switch(host->card, md->part_type);
-		if (part_err) {
-			/*
-			 * We have failed to get back into the correct
-			 * partition, so we need to abort the whole request.
-			 */
-			return -ENODEV;
-		}
-	}
-	return err;
+	if (mmc_blk_part_switch(host->card, md->part_type))
+		/*
+		 * We have failed to get back into the correct
+		 * partition, so we need to abort the whole request.
+		 */
+		return -ENODEV;
+	return 0;
 }
 
 static inline void mmc_blk_reset_success(struct mmc_blk_data *md, int type)
@@ -1867,8 +1874,9 @@ static void mmc_blk_mq_rw_recovery(struct mmc_queue *mq, struct request *req)
 		return;
 
 	/* Reset before last retry */
-	if (mqrq->retries + 1 == MMC_MAX_RETRIES)
-		mmc_blk_reset(md, card->host, type);
+	if (mqrq->retries + 1 == MMC_MAX_RETRIES &&
+	    mmc_blk_reset(md, card->host, type))
+		return;
 
 	/* Command errors fail fast, so use all MMC_MAX_RETRIES */
 	if (brq->sbc.error || brq->cmd.error)
-- 
2.37.3

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