linux-kernel - Re: [PATCH 2/2] s390/iucv: Fix vargs handling in iucv_alloc

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Message-ID: <your-ad-here.call-01723573303-ext-4217@work.hours>
Date: Tue, 13 Aug 2024 20:21:43 +0200
From: Vasily Gorbik <gor@...ux.ibm.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alexandra Winter <wintera@...ux.ibm.com>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, Heiko Carstens <hca@...ux.ibm.com>,
        linux-s390@...r.kernel.org
Subject: Re: [PATCH 2/2] s390/iucv: Fix vargs handling in iucv_alloc_device()

On Tue, Aug 13, 2024 at 05:29:52PM +0200, Greg Kroah-Hartman wrote:
> On Tue, Aug 13, 2024 at 03:35:48PM +0200, Alexandra Winter wrote:
> > 
> > 
> > On 13.08.24 14:43, Greg Kroah-Hartman wrote:
> > >>> I don't understand, why can't dev_set_name() be called here?
> > >>>
> > [...]
> > > 
> > > But step back, why is this needed at all anyway?  No other subsystem or
> > > driver needs/wants this, what makes this api so special?  Why not figure
> > > out your name beforehand?
> > > 
> > > thanks,
> > 
> > 
> > Vasily, the following update to Heiko's patch does not touch lib/kobject.c
> > According to a quick test it still solves the original issue and does compile
> > with W=1 and iucv as a module.
> > 
> > diff --git a/net/iucv/iucv.c b/net/iucv/iucv.c
> > index 64102a31b569..6a819ba4ccab 100644
> > --- a/net/iucv/iucv.c
> > +++ b/net/iucv/iucv.c
> > @@ -86,13 +86,17 @@ struct device *iucv_alloc_device(const struct attribute_group **attrs,
> >  {
> >         struct device *dev;
> >         va_list vargs;
> > +       char buf[20];
> >         int rc;
> > 
> >         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
> >         if (!dev)
> >                 goto out_error;
> >         va_start(vargs, fmt);
> > -       rc = kobject_set_name_vargs(&dev->kobj, fmt, vargs);
> > +       rc = vsnprintf(buf, 20, fmt, vargs);
> > +       if (!rc)
> > +               rc = dev_set_name(dev, buf);
> 
> This looks best, let's not create a core function that no one has ever
> needed yet just for one user :)

Okay, fair enough. Thank you, Greg!

I'll drop these two patches. Alexandra, I assume you will send out your
alternative fix separately. Thank you!