Re: lockdep warning in urb.c:363 usb_submit_urb

Alan Stern
2020-03-25T20:49:10Z

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.

Raphael, now that we have the direct_complete mechanism, can we revisit
this? Should the PM core automatically call pm_runtime_set_active() if
dev->power.direct_complete isn't set? Perhaps in device_resume_early()
prior to the pm_runtime_enable() call?

It's possible we discussed this and decided against it at the time when
direct_complete was added, but if so I don't remember what was said.

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