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

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Message-ID: <2024081332-unblock-absinthe-1c26@gregkh>
Date: Tue, 13 Aug 2024 17:29:52 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Alexandra Winter <wintera@...ux.ibm.com>
Cc: Vasily Gorbik <gor@...ux.ibm.com>,
	"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 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 :)

thanks,

greg k-h