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Commands using a duration limit descriptor that has limit policies set to a value other than 0x0 may be failed by the device if one of the limits are exceeded. For such commands, since the failure is the result of the user duration limit configuration and workload, the commands should not be retried and terminated immediately. Furthermore, to allow the user to differentiate these "soft" failures from hard errors due to hardware problem, a different error code than EIO should be returned. There are 2 cases to consider: (1) The failure is due to a limit policy failing the command with a check condition sense key, that is, any limit policy other than 0xD. For this case, scsi_check_sense() is modified to detect failures with the ABORTED COMMAND sense key and the COMMAND TIMEOUT BEFORE PROCESSING or COMMAND TIMEOUT DURING PROCESSING or COMMAND TIMEOUT DURING PROCESSING DUE TO ERROR RECOVERY additional sense code. For these failures, a SUCCESS disposition is returned so that scsi_finish_command() is called to terminate the command. (2) The failure is due to a limit policy set to 0xD, which result in the command being terminated with a GOOD status, COMPLETED sense key, and DATA CURRENTLY UNAVAILABLE additional sense code. To handle this case, the scsi_check_sense() is modified to return a SUCCESS disposition so that scsi_finish_command() is called to terminate the command. In addition, scsi_decide_disposition() has to be modified to see if a command being terminated with GOOD status has sense data. This is as defined in SCSI Primary Commands - 6 (SPC-6), so all according to spec, even if GOOD status commands were not checked before. If scsi_check_sense() detects sense data representing a duration limit, scsi_check_sense() will set the newly introduced SCSI ML byte SCSIML_STAT_DL_TIMEOUT. This SCSI ML byte is checked in scsi_noretry_cmd(), so that a command that failed because of a CDL timeout cannot be retried. The SCSI ML byte is also checked in scsi_result_to_blk_status() to complete the command request with the BLK_STS_DURATION_LIMIT status, which result in the user seeing ETIME errors for the failed commands. Co-developed-by: Damien Le Moal <dlemoal@kernel.org> Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com> Link: https://lore.kernel.org/r/20230511011356.227789-12-nks@flawful.org Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.