Re: [PATCH v2 2/2] s390/pci: Extend device lock to cover zpci_report_status()

On Wed, Aug 19, 2026 at 02:30:18PM -0700, Farhan Ali wrote:
> 
> On 8/19/2026 2:58 AM, Niklas Schnelle wrote:
> > As zpci_report_status() accesses the device's driver the device lock
> > needs to be held. Extend the critical section to cover the
> > zpci_report_status() call.
> >
> > Cc: [email protected]
> > Fixes: 4ec6054e7321 ("s390/pci: Report PCI error recovery results via SCLP")
> > Signed-off-by: Niklas Schnelle <[email protected]>
> > ---
> >   arch/s390/pci/pci_event.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/s390/pci/pci_event.c b/arch/s390/pci/pci_event.c
> > index 839bd91c056e..48c150d6ba81 100644
> > --- a/arch/s390/pci/pci_event.c
> > +++ b/arch/s390/pci/pci_event.c
> > @@ -256,8 +256,8 @@ static pci_ers_result_t zpci_event_attempt_error_recovery(struct pci_dev *pdev)
> >   		driver->err_handler->resume(pdev);
> >   	pci_uevent_ers(pdev, PCI_ERS_RESULT_RECOVERED);
> >   out_unlock:
> > -	device_unlock(&pdev->dev);
> >   	zpci_report_status(zdev, "recovery", status_str);
> > +	device_unlock(&pdev->dev);
> >   
> >   	return ers_res;
> >   }
> 
> AFAICT this change is correct, but should we also add a lockdep_assert 

Andy maybe the context one `__must_hold()` or something as function attribute.

> in zpci_report_status()? Since this is the only placed its called, it 
> maybe fine as is. I just fear that we could miss on getting the lock if 
> we were to re-use zpci_report_status().

Yeah, I agree. It's not obvious.

I guess the critical point here why we need the lock is this line:

		driver = to_pci_driver(pdev->dev.driver);

right? Because we assume the relation between driver and device stays intact
after we get that assignment.

Because otherwise I don't see why we must get the lock, if we get a valid
reference in zpci_report_status().

-- 
Best Regards, Benjamin Block        /        Linux on IBM Z Kernel Development
IBM Deutschland Research & Development GmbH    /   https://www.ibm.com/privacy
Vors. Aufs.-R.: Wolfgang Wendt         /        Geschäftsführung: David Faller
Sitz der Ges.: Ehningen     /     Registergericht: AmtsG Stuttgart, HRB 243294