On Fri, 2018-03-16 at 22:40 +0000, Bart Van Assche wrote:
> On Fri, 2018-03-16 at 15:31 -0700, James Bottomley wrote:
> >
> > On Fri, 2018-03-16 at 22:21 +0000, Bart Van Assche wrote:
> > >
> > > On Fri, 2018-03-16 at 15:00 -0700, James Bottomley wrote:
> > > >
> > > >
> > > > On Fri, 2018-03-16 at 10:40 -0700, Bart Van Assche wrote:
> > > > >
> > > > >
> > > > > @@ -1050,7 +1050,22 @@ static int scsi_send_eh_cmnd(struct
> > > > > scsi_cmnd
> > > > > *scmd, unsigned char *cmnd,
> > > > >
> > > > > scsi_log_send(scmd);
> > > > > scmd->scsi_done = scsi_eh_done;
> > > > > - rtn = shost->hostt->queuecommand(shost, scmd);
> > > > > + mutex_lock(&sdev->state_mutex);
> > > > > + while (sdev->sdev_state == SDEV_QUIESCE && timeleft
> > > > > > 0)
> > > > > {
> > > > > + mutex_unlock(&sdev->state_mutex);
> > > > > + SCSI_LOG_ERROR_RECOVERY(5,
> > > > > sdev_printk(KERN_DEBUG,
> > > > > sdev,
> > > > > + "%s: state %d <> %d\n", __func__,
> > > > > sdev-
> > > > > >
> > > > > >
> > > > > > sdev_state,
> > > > >
> > > > > + SDEV_QUIESCE));
> > > > > + delay = min(timeleft, stall_for);
> > > > > + timeleft -= delay;
> > > > > + msleep(jiffies_to_msecs(delay));
> > > > > + mutex_lock(&sdev->state_mutex);
> > > > > + }
> > > >
> > > > What's the point of this loop? if you eliminate it, you still
> > > > get
> > > > exactly the same msleep from the stall_for retry processing.
> > >
> > > Hello James,
> > >
> > > The purpose of that loop is to check the SCSI device state every
> > > "stall_for" jiffies and to avoid that more than "timeleft"
> > > jiffies is
> > > spent on waiting.
> >
> > I know what the loop does; the the question I was asking is doesn't
> > setting rtn instead of calling ->queuecommand() achieve the same
> > thing?
>
> Sorry but I don't understand that last question. How could setting
> rtn be an alternative for calling ->queuecommand() since we really
> want to call ->queuecommand if the SCSI device leaves the quiesced
> state before the timeout has expired? Can you rephrase that last
> question?
In your new code you have
+ if (sdev->sdev_state != SDEV_QUIESCE)
+ rtn = shost->hostt->queuecommand(shost, scmd);
+ else
+ rtn = SCSI_MLQUEUE_DEVICE_BUSY;
That sets rtn instead of calling queuecommand
Then you drop through to this code below:
if (rtn) {
if (timeleft > stall_for) {
scsi_eh_restore_cmnd(scmd, &ses);
timeleft -= stall_for;
msleep(jiffies_to_msecs(stall_for));
goto retry;
}
Which causes a msleep which is equivalent to the while loop.
James
