linux-kernel - [PATCH] mmc: block: fix read single on recovery logic

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Message-ID: <5e5f2e45d0a14a55a8b7a9357846114b@hyperstone.com>
Date:   Wed, 5 Jan 2022 16:43:35 +0000
From:   Christian Löhle <CLoehle@...erstone.com>
To:     "ulf.hansson@...aro.org" <ulf.hansson@...aro.org>,
        Christian Löhle <CLoehle@...erstone.com>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Avri Altman <Avri.Altman@....com>
Subject: [PATCH] mmc: block: fix read single on recovery logic

On reads with MMC_READ_MULTIPLE_BLOCK that fail,
the recovery handler will use MMC_READ_SINGLE_BLOCK for
each of the blocks, up to MMC_READ_SINGLE_RETRIES times each.
The logic for this is fixed to never report unsuccessful reads
as success to the block layer.

On command error with retries remaining, blk_update_request was
called with whatever value error was set last to.
In case it was last set to BLK_STS_OK (default), the read will be
reported as success, even though there was no data read from the device.
This could happen on a CRC mismatch for the response,
a card rejecting the command (e.g. again due to a CRC mismatch).
In case it was last set to BLK_STS_IOERR, the error is reported correctly,
but no retries will be attempted.

The patch now will count both command and data errors as retries and
send BLK_STS_IOERR if there are no retries remaining,
or BLK_STS_OK if the single read was successful in the meantime.

Signed-off-by: Christian Loehle <cloehle@...erstone.com>
---
 drivers/mmc/core/block.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index 90e1bcd03b46..d7d880ce0f8a 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -1682,31 +1682,31 @@ static void mmc_blk_read_single(struct mmc_queue *mq, struct request *req)
 	struct mmc_card *card = mq->card;
 	struct mmc_host *host = card->host;
 	blk_status_t error = BLK_STS_OK;
-	int retries = 0;

 	do {
 		u32 status;
 		int err;
+		int retries = 0;

-		mmc_blk_rw_rq_prep(mqrq, card, 1, mq);
+		while (retries++ < MMC_READ_SINGLE_RETRIES) {
+			mmc_blk_rw_rq_prep(mqrq, card, 1, mq);

-		mmc_wait_for_req(host, mrq);
+			mmc_wait_for_req(host, mrq);

-		err = mmc_send_status(card, &status);
-		if (err)
-			goto error_exit;
-
-		if (!mmc_host_is_spi(host) &&
-		    !mmc_ready_for_data(status)) {
-			err = mmc_blk_fix_state(card, req);
+			err = mmc_send_status(card, &status);
 			if (err)
 				goto error_exit;
-		}

-		if (mrq->cmd->error && retries++ < MMC_READ_SINGLE_RETRIES)
-			continue;
+			if (!mmc_host_is_spi(host) &&
+			    !mmc_ready_for_data(status)) {
+				err = mmc_blk_fix_state(card, req);
+				if (err)
+					goto error_exit;
+			}

-		retries = 0;
+			if (!mrq->cmd->error && !mrq->data->error)
+				break;
+		}

 		if (mrq->cmd->error ||
 		    mrq->data->error ||
-- 
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