From: David Miller <davem@davemloft.net>
To: herbert@gondor.apana.org.au
Cc: john.r.fastabend@intel.com, netdev@vger.kernel.org
Subject: Re: [RFC PATCH] net: consolidate netif_needs_gso() checks
Date: Fri, 08 Jan 2010 01:00:49 -0800 (PST) [thread overview]
Message-ID: <20100108.010049.218930041.davem@davemloft.net> (raw)
In-Reply-To: <20100107050721.GA2282@gondor.apana.org.au>
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Thu, 7 Jan 2010 16:07:21 +1100
> On Wed, Jan 06, 2010 at 08:34:23PM -0800, David Miller wrote:
>> From: John Fastabend <john.r.fastabend@intel.com>
>> Date: Mon, 04 Jan 2010 10:21:53 +0000
>>
>> > netif_needs_gso() is checked twice in the TX path once,
>> > before submitting the skb to the qdisc and once after
>> > it is dequeued from the qdisc just before calling
>> > ndo_hard_start(). This opens a window for a user to
>> > change the gso/tso or tx checksum settings that can
>> > cause netif_needs_gso to be true in one check and false
>> > in the other.
>> >
>> > Specifically, changing TX checksum setting may cause
>> > the warning in skb_gso_segment() to be triggered if
>> > the checksum is calculated earlier.
>> >
>> > This consolidates the netif_needs_gso() calls so that
>> > the stack only checks if gso is needed after the skb
>> > is dequeued from the qdisc. Or if the device has no
>> > queue then before dev_hard_start_xmit() in dev_queue_xmit().
>> >
>> > Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
>>
>> Herbert, please review.
>
> Looks fine to me. I have just one suggestion. The queueless
> case also calls dev_hard_start_xmit so we should be able to
> remove the existing !need_gso code from dev_queue_xmit completely.
John, please make these changes.
Thanks.
prev parent reply other threads:[~2010-01-08 9:00 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-04 10:21 [RFC PATCH] net: consolidate netif_needs_gso() checks John Fastabend
2010-01-07 4:34 ` David Miller
2010-01-07 5:07 ` Herbert Xu
2010-01-08 9:00 ` David Miller [this message]
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