Re: [PATCH 1/3] usb: misc: ljca: move usb_autopm_put_interface() after wait for response

[Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>]

On Mon, Nov 04, 2024 at 02:39:57PM +0100, Hans de Goede wrote:
> Hi,
> 
> On 4-Nov-24 9:50 AM, Stanislaw Gruszka wrote:
> > Do not mark interface as ready to suspend when we are still waiting
> > for response messages from the device.
> > 
> > Fixes: acd6199f195d ("usb: Add support for Intel LJCA device")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
> > ---
> >  drivers/usb/misc/usb-ljca.c | 5 ++---
> >  1 file changed, 2 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/usb/misc/usb-ljca.c b/drivers/usb/misc/usb-ljca.c
> > index 01ceafc4ab78..dcb3c5d248ac 100644
> > --- a/drivers/usb/misc/usb-ljca.c
> > +++ b/drivers/usb/misc/usb-ljca.c
> > @@ -332,9 +332,6 @@ static int ljca_send(struct ljca_adapter *adap, u8 type, u8 cmd,
> >  
> >  	ret = usb_bulk_msg(adap->usb_dev, adap->tx_pipe, header,
> >  			   msg_len, &transferred, LJCA_WRITE_TIMEOUT_MS);
> > -
> > -	usb_autopm_put_interface(adap->intf);
> > -
> >  	if (ret < 0)
> >  		goto out;
> >  	if (transferred != msg_len) {
> > @@ -353,6 +350,8 @@ static int ljca_send(struct ljca_adapter *adap, u8 type, u8 cmd,
> >  	ret = adap->actual_length;
> >  
> >  out:
> > +	usb_autopm_put_interface(adap->intf);
> > +
> 
> I'm afraid that this now does a double pm_runtime_put() on
> usb_autopm_get_interface() failures. usb_autopm_get_interface() uses
> pm_runtime_resume_and_get() which already does a pm_runtime_put()
> on failure.
> 
> So you need to add a second out label which skips the new
> location of the usb_autopm_put_interface(adap->intf); call
> and jump to this second label on usb_autopm_get_interface()
> failures.

Good point, thanks for catching this, I will fix and post v2.

Regards
Stanislaw