Re: [PATCH] target: Allow for target_submit_cmd() returning errors

[Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>]

On 07/18/2012 02:05 AM, Nicholas A. Bellinger wrote:
> > index 02ace18..9ddf315 100644
> > --- a/drivers/usb/gadget/tcm_usb_gadget.c
> > +++ b/drivers/usb/gadget/tcm_usb_gadget.c
> > @@ -1060,7 +1060,10 @@ static void usbg_cmd_work(struct work_struct *work)
> >   	tpg = cmd->fu->tpg;
> >   	tv_nexus = tpg->tpg_nexus;
> >   	dir = get_cmd_dir(cmd->cmd_buf);
> > -	if (dir<  0) {
> > +	if (dir<  0 ||
> > +	    target_submit_cmd(se_cmd, tv_nexus->tvn_se_sess,
> > +			      cmd->cmd_buf, cmd->sense_iu.sense, cmd->unpacked_lun,
> > +			      0, cmd->prio_attr, dir, TARGET_SCF_UNKNOWN_SIZE)) {
> >   		transport_init_se_cmd(se_cmd,
> >   				tv_nexus->tvn_se_sess->se_tpg->se_tpg_tfo,
> >   				tv_nexus->tvn_se_sess, cmd->data_len, DMA_NONE,
> > @@ -1069,12 +1072,7 @@ static void usbg_cmd_work(struct work_struct *work)
> >   		transport_send_check_condition_and_sense(se_cmd,
> >   				TCM_UNSUPPORTED_SCSI_OPCODE, 1);
> >   		usbg_cleanup_cmd(cmd);
> > -		return;
> >   	}
> > -
> > -	target_submit_cmd(se_cmd, tv_nexus->tvn_se_sess,
> > -			cmd->cmd_buf, cmd->sense_iu.sense, cmd->unpacked_lun,
> > -			0, cmd->prio_attr, dir, TARGET_SCF_UNKNOWN_SIZE);
> >   }
> >
> >   static int usbg_submit_command(struct f_uas *fu,
>
> Looking at this part again target_submit_cmd() has been moved ahead of
> target_init_se_cmd() in the exception path, which ends up getting called
> twice during a target_get_sess_cmd() failure..
>
> It looks like usbg_cmd_work() + bot_cmd_work() will need some work if
> they intends to use a non zero failure to signal exception here, without
> invoking a CHECK_CONDITION and sense.  Actually, I'm not even sure
> sending a CHECK_CONDITION here after the target_submit_cmd() is going to
> work for other fabrics drivers, but it appears to work with usb-gadget.
> (Sebastian..?)

For UAS the status/ sense URB is sent right away (without any data) and
this worked the last time I tested.
For BOT things are a little complicated. What I do is to send empty
data (to fill the data pipe) and send a bad status so the other side
learns that the transfer failed somehow. The sense information is lost.
What I should do is to queue this sense data for the next MODE_SENSE
request which will be coming soon. Right now WinXP repeats a failed
command thrice if MODE_SENSE returns no error. "This" is on my to-fix
list…

> So for the moment, lets fix the double se_cmd init and make things a
> little easier to read..   Sebastian, please have a look and double check
> that the (dir<  0) + target_submit_cmd() failures cases are both going
> to work as expected whilst sending a CHECK_CONDITION response.

The sense code should only be sent once and
transport_send_check_condition_and_sense() sets
SCF_SENT_CHECK_CONDITION and checks for it so doing it twice should not
do any harm right? But grep does not say when this flag gets removed.

> Thanks!
>
> --nab

Sebastian
--
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html