[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <1336014869.22133.821.camel@edumazet-glaptop>
Date: Thu, 03 May 2012 05:14:29 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: Alexander Duyck <alexander.duyck@...il.com>
Cc: Alexander Duyck <alexander.h.duyck@...el.com>,
David Miller <davem@...emloft.net>,
netdev <netdev@...r.kernel.org>,
Neal Cardwell <ncardwell@...gle.com>,
Tom Herbert <therbert@...gle.com>,
Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
Michael Chan <mchan@...adcom.com>,
Matt Carlson <mcarlson@...adcom.com>,
Herbert Xu <herbert@...dor.apana.org.au>,
Ben Hutchings <bhutchings@...arflare.com>,
Ilpo Järvinen <ilpo.jarvinen@...sinki.fi>,
Maciej Żenczykowski <maze@...gle.com>
Subject: Re: [PATCH net-next] net: take care of cloned skbs in
tcp_try_coalesce()
On Wed, 2012-05-02 at 20:00 -0700, Alexander Duyck wrote:
> This is exactly my point. The way your current code works the check in
> pskb_expand_head will not detect the header is cloned.
>
> So for example lets say you have one of your skbs that goes through and
> is merged.
>
> 1. You start with a cloned skb. dataref = 2, head_frag page count = 1;
> 2. You go through tcp_try_coalesce. dataref = 2, head_frag page count = 2;
> 3. You call __kfree_skb on the skb. dataref = 1, head_frag page count = 2;
If page count was incremented in 2., this is because we stole the head.
But we could not stole the head since dataref = 2
So try to find a real example, based on current state, not on the first
patch I sent, since we made progress since this time.
Thanks
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists