lists.openwall.net   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  linux-hardening  linux-cve-announce  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:   Wed, 17 Apr 2019 10:17:09 +0100
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>
Cc:     Johannes Berg <johannes@...solutions.net>,
        Arend Van Spriel <arend.vanspriel@...adcom.com>,
        Felix Fietkau <nbd@....name>, linux-wireless@...r.kernel.org,
        Eric Dumazet <eric.dumazet@...il.com>, netdev@...r.kernel.org
Subject: Re: [PATCH 5/5] mac80211: set NETIF_F_LLTX when using intermediate tx queues

Herbert Xu <herbert@...dor.apana.org.au> writes:

> On Tue, Apr 16, 2019 at 02:18:36PM +0100, Toke Høiland-Jørgensen wrote:
>>
>> > The congestion control happens at two levels. You are right that the
>> > socket buffer acts as one limit. However, other applications may also
>> > rely on the TX queue being full as the throttle (by setting a
>> > sufficiently large socket buffer size).
>> 
>> Do you happen to have an example of an application that does this that
>> could be used for testing? :)
>
> Have a look at
>
> commit 6ce9e7b5fe3195d1ae6e3a0753d4ddcac5cd699e
> Author: Eric Dumazet <eric.dumazet@...il.com>
> Date:   Wed Sep 2 18:05:33 2009 -0700
>
>     ip: Report qdisc packet drops
>
> You should be able to do a UDP flood while setting IP_RECVERR to
> detect the packet drop due to a full queue which AFAICS will never
> happen with the current mac80211 setup.

Also, looking at udp.c, it seems it uses net_xmit_errno() - which means
that returning NET_XMIT_CN has the same effect as NET_XMIT_SUCCESS when
propagated back to userspace? Which would kinda defeat the point of
going to the trouble of propagating up the return code (the mac80211
queue will never drop the most recently enqueued packet)...

-Toke

Powered by blists - more mailing lists