Re: [PATCH] scsi: fix hung_task when change host from recovery to running via sysfs

[yebin (H)]

On 2023/3/21 22:22, Benjamin Block wrote:
> On Tue, Mar 21, 2023 at 04:42:04PM +0800, Ye Bin wrote:
> > From: Ye Bin <yebin10@xxxxxxxxxx>
> >
> > When do follow test:
> > Step1: echo  "recovery" > /sys/class/scsi_host/host0/state
> Hmm, that make me wonder, what potential use-case this is for? Just
> testing?
Thank you for your reply.
Actually, I'm looking for a way to temporarily stop sending IO to the 
driver.
Setting the state of the host to recovery can do this, but I changed the 
state to
running and found that the process could not be woken up.
I don't know what the purpose of designing this sysfs interface was. But 
this
modification can solve the effect I want to achieve.
> For SDEVs we explicitly filter what states can be set from user-space.
> Only `SDEV_RUNNING` and `SDEV_OFFLINE` can be set in
> `store_state_field()`.
>      There is probably quite a few other bad things you can do with this
> interface by using any of the other states used for device destruction
> or EH, and then trigger I/O or said destruction/EH otherwise.
>      Not sure handling this one special case of `SHOST_RECOVERY` is quite
> enough.
>
>
> > diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
> > index ee28f73af4d4..ae6b1476b869 100644
> > --- a/drivers/scsi/scsi_sysfs.c
> > +++ b/drivers/scsi/scsi_sysfs.c
> > @@ -216,6 +216,9 @@ store_shost_state(struct device *dev, struct device_attribute *attr,
> >
> >        if (scsi_host_set_state(shost, state))
> >                return -EINVAL;
> > +     else
> > +             wake_up(&shost->host_wait);
> > +
> >        return count;
> >   }
> >
> > --
> > 2.31.1