On 1/12/23 15:03, Niklas Cassel wrote:
In SCSI, we get the sense data as part of the completion, for ATA
however, we need to fetch the sense data as an extra step. For an
aborted ATA command the sense data is fetched via libata's
->eh_strategy_handler().
For Command Duration Limits policy 0xD:
The device shall complete the command without error with the additional
sense code set to DATA CURRENTLY UNAVAILABLE.
In order to handle this policy in libata, we intend to send a successful
command via SCSI EH, and let libata's ->eh_strategy_handler() fetch the
sense data for the good command. This is similar to how we handle an
aborted ATA command, just that we need to read the Successful NCQ
Commands log instead of the NCQ Command Error log.
When we get a SATA completion with successful commands, ATA_SENSE will
be set, indicating that some commands in the completion have sense data.
The sense_valid bitmask in the Sense Data for Successful NCQ Commands
log will inform exactly which commands that had sense data, which might
be a subset of all the commands that was completed in the same
completion. (Yet all will have ATA_SENSE set, since the status is per
completion.)
The successful commands that have e.g. a "DATA CURRENTLY UNAVAILABLE"
sense data will have a SCSI ML byte set, so scsi_eh_flush_done_q() will
not set the scmd->result to DID_TIME_OUT for these commands. However,
the successful commands that did not have sense data, must not get their
result marked as DID_TIME_OUT by SCSI EH.
Add a new flag SCMD_EH_SUCCESS_CMD, which tells SCSI EH to not mark a
command as DID_TIME_OUT, even if it has scmd->result == SAM_STAT_GOOD.
This will be used by libata in a follow-up patch.
Signed-off-by: Niklas Cassel <niklas.cassel@xxxxxxx>
---
drivers/scsi/scsi_error.c | 3 ++-
include/scsi/scsi_cmnd.h | 5 +++++
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 2aa2c2aee6e7..51aa5c1e31b5 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -2165,7 +2165,8 @@ void scsi_eh_flush_done_q(struct list_head *done_q)
* scsi_eh_get_sense), scmd->result is already
* set, do not set DID_TIME_OUT.
*/
- if (!scmd->result)
+ if (!scmd->result &&
+ !(scmd->flags & SCMD_EH_SUCCESS_CMD))
scmd->result |= (DID_TIME_OUT << 16);
SCSI_LOG_ERROR_RECOVERY(3,
scmd_printk(KERN_INFO, scmd,
Wouldn't it be better to use '!scmd->result && !scsi_sense_valid(scmd)'
instead of a new flag?
After all, if we have a valid sense code we _have_ been able to
communicate with the device. And as we did so it's questionable whether
it should count as a command time out ...
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@xxxxxxx +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Ivo Totev, Andrew
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