On 9/10/24 00:42, Niklas Cassel wrote:
> When ata_qc_complete() schedules a command for EH using
> ata_qc_schedule_eh(), blk_abort_request() will be called, which leads to
> req->q->mq_ops->timeout() / scsi_timeout() being called.
>
> scsi_timeout(), if the LLDD has no abort handler (libata has no abort
> handler), will set host byte to DID_TIME_OUT, and then call
> scsi_eh_scmd_add() to add the command to EH.
>
> Thus, when commands first enter libata's EH strategy_handler, all the
> commands that have been added to EH will have DID_TIME_OUT set.
>
> libata has its own flag (AC_ERR_TIMEOUT), that it sets for commands that
> have not received a completion at the time of entering EH.
>
> Thus, libata doesn't really care about DID_TIME_OUT at all, and currently
> clears the host byte at the end of EH, in ata_scsi_qc_complete(), before
> scsi_eh_finish_cmd() is called.
>
> However, this clearing in ata_scsi_qc_complete() is currently only done
> for commands that are not ATA passthrough commands.
>
> Since the host byte is visible in the completion that we return to user
> space for ATA passthrough commands, for ATA passthrough commands that got
> completed via EH (commands with sense data), the user will incorrectly see:
> ATA pass-through(16): transport error: Host_status=0x03 [DID_TIME_OUT]
>
> Fix this by moving the clearing of the host byte (which is currently only
> done for commands that are not ATA passthrough commands) from
> ata_scsi_qc_complete() to the start of EH (regardless if the command is
> ATA passthrough or not).
>
> While at it, use the proper helper function to clear the host byte, rather
> than open coding the clearing.
>
> This will make sure that we:
> -Correctly clear DID_TIME_OUT for both ATA passthrough commands and
> commands that are not ATA passthrough commands.
> -Do not needlessly clear the host byte for commands that did not go via EH.
> ata_scsi_qc_complete() is called both for commands that are completed
> normally (without going via EH), and for commands that went via EH,
> however, only commands that went via EH will have DID_TIME_OUT set.
>
> Fixes: 24aeebbf8ea9 ("scsi: ata: libata: Change ata_eh_request_sense() to not set CHECK_CONDITION")
> Reported-by: Igor Pylypiv <ipylypiv@xxxxxxxxxx>
> Closes: https://lore.kernel.org/linux-ide/ZttIN8He8TOZ7Lct@xxxxxxxxxx/
> Signed-off-by: Niklas Cassel <cassel@xxxxxxxxxx>
Applied to for-6.12. Thanks !
--
Damien Le Moal
Western Digital Research
