Re: [PATCH v15 5/5] s390/pci: Fix circular/recursive deadlocks in PCI-bus and -device release

[Benjamin Block <bblock@linux.ibm.com>]

On Thu, Sep 24, 2026 at 04:44:06PM +0000, sashiko-bot@kernel.org wrote:
> > diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
> > index d64c544b32b0c..4fc3e3dc87ad1 100644
> > --- a/arch/s390/pci/pci.c
> > +++ b/arch/s390/pci/pci.c
> > @@ -1208,7 +1212,8 @@ static int __init pci_base_init(void)
> >  	if (rc)
> >  		goto out_irq;
> >  
> > -	rc = zpci_scan_devices();
> > +	scoped_guard(pci_rescan_remove)
> > +		rc = zpci_scan_devices();
> >  	if (rc)
> >  		goto out_find;
> 
> The pci_base_init() function contains multiple goto statements for error
> handling, and this patch introduces a scoped_guard() into the same routine.
> The cleanup.h guidelines state that usage of goto and cleanup helpers should
> never be mixed in the same function.
--8<--
> > diff --git a/arch/s390/pci/pci_event.c b/arch/s390/pci/pci_event.c
> > index f317a1465dad8..268f435677ae3 100644
> > --- a/arch/s390/pci/pci_event.c
> > +++ b/arch/s390/pci/pci_event.c
> > @@ -382,6 +382,7 @@ static void __zpci_event_error(struct zpci_ccdf_err *ccdf)
> >  	pci_dev_put(pdev);
> >  no_pdev:
> >  	mutex_unlock(&zdev->state_lock);
> > +	guard(pci_rescan_remove)();
> >  	zpci_zdev_put(zdev);
> >  }
> 
> In __zpci_event_error(), there are goto statements used for error handling,
> and this patch introduces a guard() right at the cleanup label. Mixing goto
> with cleanup.h helpers in the same function goes against the subsystem
> guidelines.

So as far as I know this rule from cleanup.h is motivated by cases where
someone jumps *into* a cleanup-scope and thus skips the initialization, but
executes the cleanup, which then breaks.

This shouldn't be a problem here, but if our s390 maintainers think this
should be changed regardless, I can use ordinary calls in those two cases,
since it's probably not worth converting the whole functions here.

-- 
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