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

yebin (H)
2023-03-22T01:24:43Z

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@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?
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
>>