lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Tue, 01 Nov 2016 06:33:09 -0700
From:   Eric Dumazet <>
To:     Ilya Lesokhin <>
Cc:     "" <>,
        tls-fpga-sw-dev <>,
        Ilpo Järvinen <>
Subject: Re: Why does tcp collapse behavior depend on nr_frags?

On Tue, 2016-11-01 at 08:15 +0000, Ilya Lesokhin wrote:
> Hi,
> I've notice that tcp_can_collapse() returns false if skb_shinfo(skb)->nr_frags != 0.
> Is there a reason why we want to base the collapse decision in retransmission on whether
> the data is located in a frag or the linear part?
> The relevant commit is
> 	 tcp: collapse more than two on retransmission  ('4a17fc3add594fcc1c778e93a95b6ecf47f630e5')
> Thanks,
> Ilya

Good point.

I am guessing you see this after commit
("tcp: prepare skbs for better sack shifting")  ?

Problem is that the left skb might have no skb_availroom() anyway...

We could theoretically use the same helpers we use at sack shifting,
but are these collapse events frequent enough we should care ?

Thanks !

Powered by blists - more mailing lists