linux-kernel - Re: [PATCH] driver: dont update dev

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Date:	Sat, 18 Apr 2009 22:11:14 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Greg KH <gregkh@...e.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-pci@...r.kernel.org
Subject: Re: [PATCH] driver: dont update dev_name if it is not changed


* Yinghai Lu <yinghai@...nel.org> wrote:

> notice one system /proc/iomem some entries missed the name for pci_devices
> 
> it turns that dev->dev.kobj name is changed after device_add.
> 
> [Impact: fix corrupted names in /proc/iomem ]
> 
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> 
> ---
>  lib/kobject.c |   13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> Index: linux-2.6/lib/kobject.c
> ===================================================================
> --- linux-2.6.orig/lib/kobject.c
> +++ linux-2.6/lib/kobject.c
> @@ -216,12 +216,21 @@ int kobject_set_name_vargs(struct kobjec
>  				  va_list vargs)
>  {
>  	const char *old_name = kobj->name;
> +	char *new_name;
>  	char *s;
>  
> -	kobj->name = kvasprintf(GFP_KERNEL, fmt, vargs);
> -	if (!kobj->name)
> +	new_name = kvasprintf(GFP_KERNEL, fmt, vargs);
> +	if (!new_name)
>  		return -ENOMEM;
>  
> +	/* different ? */
> +	if (!strcmp(new_name, old_name)) {
> +		kfree(new_name);
> +		return 0;
> +	}
> +
> +	kobj->name = new_name;
> +
>  	/* ewww... some of these buggers have '/' in the name ... */
>  	while ((s = strchr(kobj->name, '/')))
>  		s[0] = '!';

So we used the old name in the resource code, and the kfree() here 
corrupted the /proc/iomem output?

This still looks fragile to me ...

	Ingo
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