Re: [PATCH] SCSI: delay run queue if device is blocked in scsi_dev_queue_ready()

[Ming Lei <ming.lei@redhat.com>]

On Mon, Dec 04, 2017 at 09:19:33AM +0100, Johannes Thumshirn wrote:
> 
> Hi Ming,
> 
> Ming Lei <ming.lei@redhat.com> writes:
> > This issue can be triggered by the following script:
> >
> > 	#!/bin/sh
> > 	rmmod scsi_debug
> > 	modprobe scsi_debug max_queue=1
> >
> > 	DEVICE=`ls -d /sys/bus/pseudo/drivers/scsi_debug/adapter*/host*/target*/*/block/* | head -1 | xargs basename`
> >
> > 	DISK_DIR=`ls -d /sys/block/$DEVICE/device/scsi_disk/*`
> >
> > 	echo "using scsi device $DEVICE"
> > 	echo "-1" >/sys/bus/pseudo/drivers/scsi_debug/every_nth
> > 	echo starting loop $i
> > 	echo "temporary write through" >$DISK_DIR/cache_type
> > 	echo "128" >/sys/bus/pseudo/drivers/scsi_debug/opts
> > 	echo none > /sys/block/$DEVICE/queue/scheduler
> > 	dd if=/dev/$DEVICE of=/dev/null bs=1M iflag=direct count=1 &
> > 	sleep 5
> > 	echo "0" >/sys/bus/pseudo/drivers/scsi_debug/opts
> > 	wait
> > 	echo "SUCCESS"
> 
> Can you please submit a test-case for blktest as well, given you have a
> nice reproducer?

Hi Johannes,

I am happy to do that, but recently I am very busy, so it may be done
a bit late by me.

But anyone should reproduce the issue 100% with V4.15-rc kernel by just
running the above script, not any specific hardware is required at all,
so that means anyone can make a patch for blktest to test block/SCSI
timeout if he/she is interested in doing that.

Thanks,
Ming