netdev - Re: a problem tcp_v4

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Date:	Fri, 12 Nov 2010 19:12:58 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Alexey Kuznetsov <kuznet@....inr.ac.ru>
Cc:	Patrick McHardy <kaber@...sh.net>,
	David Lamparter <equinox@...c24.net>,
	Eric Paris <eparis@...hat.com>, Hua Zhong <hzhong@...il.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	davem@...emloft.net, pekkas@...core.fi, jmorris@...ei.org,
	yoshfuji@...ux-ipv6.org, paul.moore@...com
Subject: Re: a problem tcp_v4_err()

Le vendredi 12 novembre 2010 à 20:57 +0300, Alexey Kuznetsov a écrit :
> Hello!
> 
> I looked at tcp_v4_err() and found something strange. Quite non-trivial operations
> are performed on unlocked sockets. It looks like at least this BUG_ON():
> 
>                 skb = tcp_write_queue_head(sk);
>                 BUG_ON(!skb);
> 
> can be easily triggered.
> 
> Do I miss something?
> 

Hi Alexey !

I see socket is locked around line 368,

        bh_lock_sock(sk);
        /* If too many ICMPs get dropped on busy
         * servers this needs to be solved differently.
         */
        if (sock_owned_by_user(sk))
                NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);


Hmm, maybe some goto is missing ;)



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