netdev - Re: [PATCH net-next-2.6] net: dont hold rtnl mutex during netlink dump callbacks

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]

Message-ID: <20110428084337.6b54603e@nehalam>
Date:	Thu, 28 Apr 2011 08:43:37 -0700
From:	Stephen Hemminger <shemminger@...tta.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	David Miller <davem@...emloft.net>,
	Patrick McHardy <kaber@...sh.net>,
	netdev <netdev@...r.kernel.org>,
	Remi Denis-Courmont <remi.denis-courmont@...ia.com>
Subject: Re: [PATCH net-next-2.6] net: dont hold rtnl mutex during netlink
 dump callbacks

On Thu, 28 Apr 2011 10:56:07 +0200
Eric Dumazet <eric.dumazet@...il.com> wrote:

> Four years ago, Patrick made a change to hold rtnl mutex during netlink
> dump callbacks.
> 
> I believe it was a wrong move. This slows down concurrent dumps, making
> good old /proc/net/ files faster than rtnetlink in some situations.
> 
> This occurred to me because one "ip link show dev ..." was _very_ slow
> on a workload adding/removing network devices in background.
> 
> All dump callbacks are able to use RCU locking now, so this patch does
> roughly a revert of commits :
> 
> 1c2d670f366 : [RTNETLINK]: Hold rtnl_mutex during netlink dump callbacks
> 6313c1e0992 : [RTNETLINK]: Remove unnecessary locking in dump callbacks
> 
> This let writers fight for rtnl mutex and readers going full speed.
> 
> It also takes care of phonet : phonet_route_get() is now called from rcu
> read section. I renamed it to phonet_route_get_rcu()
> 
> Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
> Cc: Patrick McHardy <kaber@...sh.net>
> Cc: Remi Denis-Courmont <remi.denis-courmont@...ia.com>

Acked-by: Stephen Hemminger <shemminger@...tta.com>

-- 
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html