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

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Message-ID: <20230321142237.GC311313@t480-pf1aa2c2.fritz.box>
Date:   Tue, 21 Mar 2023 14:22:37 +0000
From:   Benjamin Block <bblock@...ux.ibm.com>
To:     Ye Bin <yebin@...weicloud.com>
Cc:     jejb@...ux.ibm.com, martin.petersen@...cle.com,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ye Bin <yebin10@...wei.com>
Subject: Re: [PATCH] scsi: fix hung_task when change host from recovery to
 running via sysfs

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