From: Eric Dumazet <eric.dumazet@gmail.com>
To: Kevin Wilson <wkevils@gmail.com>
Cc: netdev@vger.kernel.org
Subject: Re: GSO and IPv4 forwarding
Date: Tue, 26 Oct 2010 22:15:14 +0200 [thread overview]
Message-ID: <1288124114.2652.25.camel@edumazet-laptop> (raw)
In-Reply-To: <AANLkTikxNYGFAmyZDit9fTp=-M8wfYp3Ew8rejsjHWHb@mail.gmail.com>
Le mardi 26 octobre 2010 à 22:02 +0200, Kevin Wilson a écrit :
> Hi,
> When we set a netdevice to support forwarding, we disable LRO.
> This is done because we don't want to forward an SKB which has been
> processed by LRO.
>
> This is done in inet_forward_change() in net/ipv4/devinet.c:
> We call dev_disable_lro(dev) in this method, when setting forwarding
> for the device.
> As a result, in ip_forward(), the packet will be dropped. (because
> skb_warn_if_lro(), called by this method, returns TRUE)
>
> My question is:
> dev_disable_lro(dev) disable the LRO feature (NETIF_F_LRO) of the
> device. But suppose I have a device where GRO is enabled (and LRO is
> not). And let's say I set forwarding on this device.
>
> it seems to me that is such case, calling dev_disable_lro(dev) in
> net_forward_change() to disable the LRO feature of the device (which
> is already disabled) is not enough, and in such case , GRO packets,
> which want to be forwarded, will **not** be dropped in ip_forward().
> (since kb_warn_if_lro() will return false in this case)
>
> Is it so ? I am ready to send a patch fixing it, but I am a newbie in
> kernel, so I want to ask first.
GRO packets can be forwarded just fine.
next prev parent reply other threads:[~2010-10-26 20:15 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-26 20:02 GSO and IPv4 forwarding Kevin Wilson
2010-10-26 20:15 ` Eric Dumazet [this message]
2010-10-26 20:26 ` Kevin Wilson
2010-10-26 20:43 ` Eric Dumazet
2010-10-26 20:52 ` Stephen Hemminger
2010-10-26 20:19 ` David Miller
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