linux-kernel - Re: e1000_netpoll(): disable_irq() triggers might

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: <20141029195054.GH10501@worktop.programming.kicks-ass.net>
Date:	Wed, 29 Oct 2014 20:50:54 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Sabrina Dubroca <sd@...asysnail.net>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, jeffrey.t.kirsher@...el.com
Subject: Re: e1000_netpoll(): disable_irq() triggers might_sleep() on
 linux-next

On Wed, Oct 29, 2014 at 08:49:03PM +0100, Thomas Gleixner wrote:
> On Wed, 29 Oct 2014, Peter Zijlstra wrote:
> 
> > On Wed, Oct 29, 2014 at 07:33:00PM +0100, Thomas Gleixner wrote:
> > > Yuck. No. You are just papering over the problem.
> > > 
> > > What happens if you add 'threadirqs' to the kernel command line? Or if
> > > the interrupt line is shared with a real threaded interrupt user?
> > > 
> > > The proper solution is to have a poll_lock for e1000 which serializes
> > > the hardware interrupt against netpoll instead of using
> > > disable/enable_irq().
> > > 
> > > In fact that's less expensive than the disable/enable_irq() dance and
> > > the chance of contention is pretty low. If done right it will be a
> > > NOOP for the CONFIG_NET_POLL_CONTROLLER=n case.
> > > 
> > 
> > OK a little something like so then I suppose.. But I suspect most all
> > the network drivers will need this and maybe more, disable_irq() is a
> > popular little thing and we 'just' changed semantics on them.
> 
> We changed that almost 4 years ago :) What we 'just' did was to add a
> prominent warning into the code.

You know that is the same right... they didn't know it was broken
therefore it wasn't :-), but now they need to go actually do stuff about
it, an entirely different proposition.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/