[PATCH V14 11/24] mmc: block: Add error-handling comments

Adrian Hunter
2017-11-21T13:42:37Z

Add error-handling comments to explain what would also be done for blk-mq
if it used the legacy error-handling.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
drivers/mmc/core/block.c | 36 +++++++++++++++++++++++++++++++++++-
1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index 607774fcb9f5..56624853d3d3 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -1966,7 +1966,11 @@ static void mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *new_req)
case MMC_BLK_SUCCESS:
case MMC_BLK_PARTIAL:
/*
- * A block was successfully transferred.
+ * Reset success, and accept bytes_xfered. For
+ * MMC_BLK_PARTIAL re-submit the remaining request. For
+ * MMC_BLK_SUCCESS error out the remaining request (it
+ * could not be re-submitted anyway if a next request
+ * had already begun).
*/
mmc_blk_reset_success(md, type);

@@ -1986,6 +1990,14 @@ static void mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *new_req)
}
break;
case MMC_BLK_CMD_ERR:
+ /*
+ * For SD cards, get bytes written, but do not accept
+ * bytes_xfered if that fails. For MMC cards accept
+ * bytes_xfered. Then try to reset. If reset fails then
+ * error out the remaining request, otherwise retry
+ * once (N.B mmc_blk_reset() will not succeed twice in a
+ * row).
+ */
req_pending = mmc_blk_rw_cmd_err(md, card, brq, old_req, req_pending);
if (mmc_blk_reset(md, card->host, type)) {
if (req_pending)
@@ -2002,11 +2014,20 @@ static void mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *new_req)
}
break;
case MMC_BLK_RETRY:
+ /*
+ * Do not accept bytes_xfered, but retry up to 5 times,
+ * otherwise same as abort.
+ */
retune_retry_done = brq->retune_retry_done;
if (retry++ < 5)
break;
/* Fall through */
case MMC_BLK_ABORT:
+ /*
+ * Do not accept bytes_xfered, but try to reset. If
+ * reset succeeds, try once more, otherwise error out
+ * the request.
+ */
if (!mmc_blk_reset(md, card->host, type))
break;
mmc_blk_rw_cmd_abort(mq, card, old_req, mq_rq);
@@ -2015,6 +2036,13 @@ static void mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *new_req)
case MMC_BLK_DATA_ERR: {
int err;

+ /*
+ * Do not accept bytes_xfered, but try to reset. If
+ * reset succeeds, try once more. If reset fails with
+ * ENODEV which means the partition is wrong, then error
+ * out the request. Otherwise attempt to read one sector
+ * at a time.
+ */
err = mmc_blk_reset(md, card->host, type);
if (!err)
break;
@@ -2026,6 +2054,10 @@ static void mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *new_req)
/* Fall through */
}
case MMC_BLK_ECC_ERR:
+ /*
+ * Do not accept bytes_xfered. If reading more than one
+ * sector, try reading one sector at a time.
+ */
if (brq->data.blocks > 1) {
/* Redo read one sector at a time */
pr_warn("%s: retrying using single block read\n",
@@ -2047,10 +2079,12 @@ static void mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *new_req)
}
break;
case MMC_BLK_NOMEDIUM:
+ /* Do not accept bytes_xfered. Error out the request */
mmc_blk_rw_cmd_abort(mq, card, old_req, mq_rq);
mmc_blk_rw_try_restart(mq, new_req, mqrq_cur);
return;
default:
+ /* Do not accept bytes_xfered. Error out the request */
pr_err("%s: Unhandled return value (%d)",
old_req->rq_disk->disk_name, status);
mmc_blk_rw_cmd_abort(mq, card, old_req, mq_rq);
--
1.9.1