linux-kernel - [PATCH 3.2 48/87] libata: make ata_eh_qc_retry() bump scmd->allowed on bogus failures

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Message-ID: <lsq.1385387069.85238954@decadent.org.uk>
Date:	Mon, 25 Nov 2013 13:44:29 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Tejun Heo" <tj@...nel.org>,
	"Gwendal Grignou" <gwendal@...gle.com>
Subject: [PATCH 3.2 48/87] libata: make ata_eh_qc_retry() bump
 scmd->allowed on bogus failures

3.2.53-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Gwendal Grignou <gwendal@...gle.com>

commit f13e220161e738c2710b9904dcb3cf8bb0bcce61 upstream.

libata EH decrements scmd->retries when the command failed for reasons
unrelated to the command itself so that, for example, commands aborted
due to suspend / resume cycle don't get penalized; however,
decrementing scmd->retries isn't enough for ATA passthrough commands.

Without this fix, ATA passthrough commands are not resend to the
drive, and no error is signalled to the caller because:

- allowed retry count is 1
- ata_eh_qc_complete fill the sense data, so result is valid
- sense data is filled with untouched ATA registers.

Signed-off-by: Gwendal Grignou <gwendal@...gle.com>
Signed-off-by: Tejun Heo <tj@...nel.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/ata/libata-eh.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -1286,14 +1286,14 @@ void ata_eh_qc_complete(struct ata_queue
  *	should be retried.  To be used from EH.
  *
  *	SCSI midlayer limits the number of retries to scmd->allowed.
- *	scmd->retries is decremented for commands which get retried
+ *	scmd->allowed is incremented for commands which get retried
  *	due to unrelated failures (qc->err_mask is zero).
  */
 void ata_eh_qc_retry(struct ata_queued_cmd *qc)
 {
 	struct scsi_cmnd *scmd = qc->scsicmd;
-	if (!qc->err_mask && scmd->retries)
-		scmd->retries--;
+	if (!qc->err_mask)
+		scmd->allowed++;
 	__ata_eh_qc_complete(qc);
 }
 

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