Re: lockdep warning in urb.c:363 usb_submit_urb

Qais Yousef
2020-04-21T11:15:19Z

On 04/20/20 16:26, Alan Stern wrote:
> On Wed, 25 Mar 2020, Alan Stern wrote:
>
> > On Wed, 25 Mar 2020, Qais Yousef wrote:
> >
> > > Thanks for all the hints Alan.
> > >
> > > I think I figured it out, the below patch seems to fix it for me. Looking
> > > at other drivers resume functions it seems we're missing the
> > > pm_runtime_disable()->set_active()->enable() dance. Doing that fixes the
> > > warning and the dev_err() in driver/base/power.
> >
> > Ah, yes. This should have been added years ago; guess I forgot. :-(
> >
> > > I don't see xhci-plat.c doing that, I wonder if it needs it too.
> > >
> > > I'm not well versed about the details and the rules here. So my fix could be
> > > a hack, though it does seem the right thing to do.
> > >
> > > I wonder why the power core doesn't handle this transparently..
> >
> > Initially, we didn't want the PM core to do this automatically because
> > we thought some devices might want to remain runtime-suspended
> > following a system resume, and only the device driver would know what
> > to do.
>
> Qais:
>
> So it looks like the discussion with Rafael will lead to changes in the
> PM core, but they won't go into the -stable kernels, and they won't
> directly fix the problem here.
>
> In the meantime, why don't you write up your patch below and submit it
> properly? Even better, create similar patches for ehci-platform.c and
> xhci-plat.c and submit them too.

Sure.

Thanks

--
Qais Yousef

>
> Alan Stern
>
> > > diff --git a/drivers/usb/host/ohci-platform.c b/drivers/usb/host/ohci-platform.c
> > > index 7addfc2cbadc..eb92c8092fae 100644
> > > --- a/drivers/usb/host/ohci-platform.c
> > > +++ b/drivers/usb/host/ohci-platform.c
> > > @@ -299,6 +299,10 @@ static int ohci_platform_resume(struct device *dev)
> > > }
> > >
> > > ohci_resume(hcd, false);
> > > +
> > > + pm_runtime_disable(dev);
> > > + pm_runtime_set_active(dev);
> > > + pm_runtime_enable(dev);
> > > return 0;
> > > }
> > > #endif /* CONFIG_PM_SLEEP */
> > >
> > >
> > > Thanks
> > >
> > > --
> > > Qais Yousef
> >
> >
> >
>