From: Eric Dumazet <eric.dumazet@gmail.com>
To: David Miller <davem@davemloft.net>
Cc: grant.b.edwards@gmail.com, netdev@vger.kernel.org
Subject: Re: Change in alloc_skb() behavior in 3.2+ kernels?
Date: Wed, 06 Jun 2012 21:42:22 +0200 [thread overview]
Message-ID: <1339011742.26966.44.camel@edumazet-glaptop> (raw)
In-Reply-To: <20120606.115130.1091814494251887552.davem@davemloft.net>
On Wed, 2012-06-06 at 11:51 -0700, David Miller wrote:
> From: Grant Edwards <grant.b.edwards@gmail.com>
> Date: Wed, 6 Jun 2012 18:32:57 +0000 (UTC)
>
> > The kernel module that's started failing fills the allocated sk_buff
> > until tailroom() indicates it is full and then sends it. The problem
> > is that sending a packet with a length of 1850 won't work (it's a
> > MAC-layer Ethernet packet).
>
> The amount of tailroom an SKB has is implementation dependent.
>
> It's incredibly poor form to rely upon it to determine whether a fully
> sized frame has been constructed or not.
>
> Please fix the code that does this.
By the way, we had a similar problem, and the fix was :
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=a21d45726acacc963d8baddf74607d9b74e2b723
Grant, depending on the context, you might use skb->avail_size and
skb_availroom() as well.
Beware skb->avail_size is unioned with skb->{mark|dropcount}
next prev parent reply other threads:[~2012-06-06 19:42 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-06 18:32 Change in alloc_skb() behavior in 3.2+ kernels? Grant Edwards
2012-06-06 18:42 ` Eric Dumazet
2012-06-06 18:59 ` Grant Edwards
2012-06-06 19:02 ` David Miller
2012-06-06 20:22 ` Grant Edwards
2012-06-07 1:23 ` [PATCH net-next] net: Update kernel-doc for __alloc_skb() Ben Hutchings
2012-06-07 20:19 ` David Miller
2012-06-07 13:23 ` Change in alloc_skb() behavior in 3.2+ kernels? Grant Edwards
2012-06-07 14:01 ` Eric Dumazet
2012-06-07 14:16 ` Grant Edwards
2012-06-07 14:25 ` Eric Dumazet
2012-06-06 18:51 ` David Miller
2012-06-06 19:01 ` Grant Edwards
2012-06-06 20:17 ` David Miller
2012-06-06 20:24 ` Grant Edwards
2012-06-06 20:31 ` Eric Dumazet
2012-06-06 20:35 ` Grant Edwards
2012-06-06 19:42 ` Eric Dumazet [this message]
2012-06-06 20:26 ` Grant Edwards
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