Re: [PATCH-next v2 2/2] scsi: fix iscsi rescan fails to create block device

[Yu Kuai]

Hi, Greg

在 2023/01/28 18:45, Greg KH 写道:
> > diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
> > index cac7c902cf70..a22109cdb8ef 100644
> > --- a/drivers/scsi/scsi_sysfs.c
> > +++ b/drivers/scsi/scsi_sysfs.c
> > @@ -1535,9 +1535,7 @@ static void __scsi_remove_target(struct scsi_target *starget)
> >   		if (sdev->channel != starget->channel ||
> >   		    sdev->id != starget->id)
> >   			continue;
> > -		if (sdev->sdev_state == SDEV_DEL ||
> > -		    sdev->sdev_state == SDEV_CANCEL ||
> > -		    !get_device(&sdev->sdev_gendev))
> > +		if (!get_device_unless_zero(&sdev->sdev_gendev))
>
> If sdev_gendev is 0 here, the object is gone and you are working with
> memory that is already freed so something is _VERY_ wrong.

In fact, this patch will work:

In __scsi_remove_target(), 'host_lock' is held to protect iterating
siblings, and object will wait for this lock in
scsi_device_dev_release() to remove siblings. Hence sdev will not be
freed untill the lock is released.

Thanks,
Kuai
> This isn't ok, sorry.
>
> greg k-h
> .