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

Benjamin Block
2023-03-21T14:23:28Z

On Tue, Mar 21, 2023 at 04:42:04PM +0800, Ye Bin wrote:
> From: Ye Bin <yebin10@huawei.com>
>
> 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?

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
>

--
Best Regards, Benjamin Block / Linux on IBM Z Kernel Development
IBM Deutschland Research & Development GmbH / https://www.ibm.com/privacy
Vors. Aufs.-R.: Gregor Pillen / Geschäftsführung: David Faller
Sitz der Ges.: Böblingen / Registergericht: AmtsG Stuttgart, HRB 243294