From: Florian Westphal <fw@strlen.de>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Florian Westphal <fw@strlen.de>,
Jamal Hadi Salim <jhs@mojatatu.com>,
Cong Wang <xiyou.wangcong@gmail.com>,
David Miller <davem@davemloft.net>,
netdev <netdev@vger.kernel.org>,
Stas Nichiporovich <stasn77@gmail.com>
Subject: Re: [PATCH v2 net] fq_codel: fix NET_XMIT_CN behavior
Date: Mon, 6 Jun 2016 18:18:43 +0200 [thread overview]
Message-ID: <20160606161843.GD7827@breakpoint.cc> (raw)
In-Reply-To: <1465223845.2968.61.camel@edumazet-glaptop3.roam.corp.google.com>
Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On Mon, 2016-06-06 at 13:42 +0200, Florian Westphal wrote:
> > Jamal Hadi Salim <jhs@mojatatu.com> wrote:
> > > BTW, returning NET_XMIT_CN could be confusing to tcp;
> > > it does not mean that the packet that we are getting return
> > > code for was dropped; it could mean _another_ packet in
> > > the queue was dropped.
> >
> > Yes, but we currently conceal NET_XMIT_CN from upper layer (tcp)
> > via the net_xmit_* macros:
> >
> > #define net_xmit_eval(e) ((e) == NET_XMIT_CN ? 0 : (e))
> > #define net_xmit_errno(e) ((e) != NET_XMIT_CN ? -ENOBUFS : 0)
> >
> > Might be worth changing this so tcp reduces cwnd in _CN case too.
>
> It always had been the case.
>
> tcp_transmit_skb() calls tcp_enter_cwr(), unless someone broke this.
No, you're right. We hide error in ip_send_skb but that function is
not used in tcp case.
So all is good here.
next prev parent reply other threads:[~2016-06-06 16:18 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-04 17:43 [PATCH net] fq_codel: fix NET_XMIT_CN behavior Eric Dumazet
2016-06-04 19:03 ` [net] " Florian Westphal
2016-06-04 19:40 ` Eric Dumazet
2016-06-04 19:55 ` [PATCH v2 net] " Eric Dumazet
2016-06-05 13:03 ` Jamal Hadi Salim
2016-06-05 20:30 ` Cong Wang
2016-06-05 20:54 ` Eric Dumazet
2016-06-05 20:55 ` Eric Dumazet
2016-06-05 23:30 ` Cong Wang
2016-06-06 10:49 ` Jamal Hadi Salim
2016-06-06 11:42 ` Florian Westphal
2016-06-06 14:37 ` Eric Dumazet
2016-06-06 16:18 ` Florian Westphal [this message]
2016-06-10 12:02 ` Jamal Hadi Salim
2016-06-06 14:29 ` Eric Dumazet
2016-06-07 22:39 ` David Miller
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