netdev - Re: [PATCH][NET-2.6.24] Remove double dev->flags checking when calling dev

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Date:	Tue, 09 Oct 2007 15:44:40 +0400
From:	Pavel Emelyanov <xemul@...nvz.org>
To:	Jeff Garzik <jeff@...zik.org>
CC:	David Miller <davem@...emloft.net>,
	Linux Netdev List <netdev@...r.kernel.org>, devel@...nvz.org
Subject: Re: [PATCH][NET-2.6.24] Remove double dev->flags checking when calling
 dev_close()

Jeff Garzik wrote:
> Pavel Emelyanov wrote:
>> The unregister_netdevice() and dev_change_net_namespace() 
>> both check for dev->flags to be IFF_UP before calling the 
>> dev_close(), but the dev_close() checks for IFF_UP itself, 
>> so remove those unneeded checks.
>>
>> Signed-off-by: Pavel Emelyanov <xemul@...nvz.org>
>>
>> ---
>>
>> diff --git a/net/core/dev.c b/net/core/dev.c
>> index e7e728a..1e169a5 100644
>> --- a/net/core/dev.c
>> +++ b/net/core/dev.c
>> @@ -3893,8 +3893,7 @@ void unregister_netdevice(struct net_dev
>>  	BUG_ON(dev->reg_state != NETREG_REGISTERED);
>>  
>>  	/* If device is running, close it first. */
>> -	if (dev->flags & IFF_UP)
>> -		dev_close(dev);
>> +	dev_close(dev);
>>  
>>  	/* And unlink it from device chain. */
>>  	unlist_netdevice(dev);
>> @@ -4018,8 +4017,7 @@ int dev_change_net_namespace(struct net_
>>  	 */
>>  
>>  	/* If device is running close it first. */
>> -	if (dev->flags & IFF_UP)
>> -		dev_close(dev);
>> +	dev_close(dev);
>>  
>>  	/* And unlink it from device chain */
>>  	err = -ENODEV;
> 
> One side effect of this patch:  might_sleep() is now called unconditionally.

That's not a big deal - see, the synchronize_net() is called further
in both places unconditionally (!) and also calls might_sleep(), so
this is OK.

> If that is irrelevant... ACK.

Thanks :)

> 
> -
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