netdev - Re: [PATCH 1/2] genl: Fix genl dumpit() locking.

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Message-ID: <1377242982.14021.8.camel@jlt4.sipsolutions.net>
Date:	Fri, 23 Aug 2013 09:29:42 +0200
From:	Johannes Berg <johannes@...solutions.net>
To:	Pravin Shelar <pshelar@...ira.com>
Cc:	netdev <netdev@...r.kernel.org>, Jesse Gross <jesse@...ira.com>
Subject: Re: [PATCH 1/2] genl: Fix genl dumpit() locking.

On Thu, 2013-08-22 at 13:31 -0700, Pravin Shelar wrote:
> On Thu, Aug 22, 2013 at 11:18 AM, Johannes Berg
> <johannes@...solutions.net> wrote:
> > On Thu, 2013-08-22 at 11:10 -0700, Pravin Shelar wrote:
> >
> >> > By the way - why? This just means that netlink will allocate another
> >> > lock to lock it all, so it's not a very useful change?
> >> >
> >> This replaces global genl-lock with per-socket lock which allows
> >> parallel operation in parallel-genl-families and they are not blocked
> >> due to other unrelated genl-family operations.
> >
> > I don't think so? It replaces the genl lock as cb_mutex with a per
> > *kernel* socket lock, so really just one per network namespace. That's
> > not much of an improvement really.
> >
> 
> You are thinking abt genl-sock -> nlk -> cb_lock which is not used in
> genl-dump locking if cb_lock is NULL while creating nl socket.

You're right, this is also done for each userland socket, so each socket
now gets its own cb_mutex. This would help genl families with
parallel_ops.

johannes

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