On Mon, Sep 09, 2024 at 09:52:53PM +0900, Damien Le Moal wrote: > On 9/9/24 17:47, 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). > > > > 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/ > > Tested-by: Igor Pylypiv <ipylypiv@xxxxxxxxxx> > > Signed-off-by: Niklas Cassel <cassel@xxxxxxxxxx> > > --- > > Changes since v1: > > -Picked up tags from Igor. > > -Added Fixes tag. > > -Improved the commit message to clearly state that this is currently a > > real bug for ATA PT commands with sense data. > > > > drivers/ata/libata-eh.c | 9 +++++++++ > > drivers/ata/libata-scsi.c | 3 --- > > 2 files changed, 9 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c > > index 7de97ee8e78b..450e9bd96c97 100644 > > --- a/drivers/ata/libata-eh.c > > +++ b/drivers/ata/libata-eh.c > > @@ -630,6 +630,15 @@ void ata_scsi_cmd_error_handler(struct Scsi_Host *host, struct ata_port *ap, > > list_for_each_entry_safe(scmd, tmp, eh_work_q, eh_entry) { > > struct ata_queued_cmd *qc; > > > > + /* > > + * If the scmd was added to EH, via ata_qc_schedule_eh() -> > > + * scsi_timeout() -> scsi_eh_scmd_add(), scsi_timeout() will > > + * have set DID_TIME_OUT (since libata does not have an abort > > + * handler). Thus to clear the DID_TIME_OUT, we clear the host > > + * byte (but keep the SCSI ML and status byte). > > + */ > > + scmd->result &= 0x0000ffff; > > I know it was like that, but why not: > > set_host_byte(scmd, 0); > or > set_host_byte(scmd, DID_OK); > > ? No particular reason. Since we basically just moving the code, it made sense to keep it similar to the original code, but I can submit a v3 that instead does: set_host_byte(scmd, DID_OK); if you prefer that. Strictly speaking, that would probably require us to drop Igor's Tested-by though (even if the generated code for an optimizing compiler ought to generate the same code). > > set_host_byte() uses the mask 0xff00ffff, since the upper 8 bits seem to be > ignored: bits [0..7] are the status byte, [16..23] are the host byte and bits > [8..15] are the message byte but that is unused. Nit: 8..16 is the SCSI midlayer byte, not message byte, see 36ebf1e2aa14 ("scsi: core: Add error codes for internal SCSI midlayer use") Kind regards, Niklas