netdev - Re: [PATCH 1/2 v2] af-packet: Use existing netdev reference for bound sockets.

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Message-ID: <4DDF2463.3020001@candelatech.com>
Date:	Thu, 26 May 2011 21:11:15 -0700
From:	Ben Greear <greearb@...delatech.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	netdev@...r.kernel.org
Subject: Re: [PATCH 1/2 v2] af-packet:  Use existing netdev reference for
 bound sockets.

On 05/26/2011 08:42 PM, Eric Dumazet wrote:
> Le jeudi 26 mai 2011 à 16:55 -0700, greearb@...delatech.com a écrit :

>>   out_free:
>>   	kfree_skb(skb);
>>   out_unlock:
>> -	if (dev)
>> +	if (dev&&  need_rls_dev)
>>   		dev_put(dev);
>>   out:
>>   	return err;
>
> Hmmm, I wonder why you want this Ben.
>
> IMHO this is buggy, because we can sleep in this function.
>
> We must take a ref on device (its really cheap these days, now we have a
> percpu device refcnt)

Why must you take the reference?  And if we must, why isn't the
current code that assigns the prot_hook.dev without taking a
reference OK?

It seems a waste to do the lookup and free if we don't have to,
and with thousands of devices, the lookup might take a reasonable
amount of effort?

Thanks,
Ben

-- 
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc  http://www.candelatech.com
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