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

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Date:	Sat, 18 Apr 2009 13:20:39 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Ingo Molnar <mingo@...e.hu>
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

Ingo Molnar wrote:
> * 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?
> 
if it is not changed, we still use old_name. and new_name get freed

YH

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