Re: [PATCH] USB: UAS: don't unbind and rebind the driver during usb_reset_device

[Oliver Neukum <oneukum@suse.com>]

Am Sonntag, den 21.02.2021, 11:20 +0100 schrieb Hans de Goede:
> Hi,

Hi,

> 
> On 2/21/21 9:51 AM, Hui Wang wrote:
> > Once pre_reset() or post_reset() returns non-zero, the disconnect()
> > and probe() of the usb_driver will be called. In the disconnect(),
> > the scsi_host will be removed and be freed after scsi_host_put(), in
> > the probe(), the new scsi_host and uas_dev_info will be created.
> > 
> > If the usb_reset_device() is triggered by eh_device_reset_handler(),
> > and pre_reset()/post_reset() returns non-zero, the disconnect() and
> > probe() will be called, then returns to the eh_device_reset_handler(),
> > it still accesses old scsi related variables and uas_dev_info, and so
> > do its caller functions.
> > 
> > Here change the pre_reset() and post_reset() to let them only return
> > 0, after this change, the usb_reset_device() will only reset this
> > usb devcie from its hub port, will not execute unbind and rebind
> > usb_driver during reset.
> 
> We only return non 0 from the pre/post reset handles if we failed
> to ensure the device is in a known state.

correct. Technically it is a bit unfortunate that UAS devices react
a bit different to other SCSI devices, but we definitely cannot hide
a failure. Arguably we should go into OFFLINE state.
But that needs a
good reason beyond theoretical considerations.

	Regards
		Oliver