linux-kernel - Re: [RFC/PATCH 3/4] genirq: system set irq affinities

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: <1204193986.6243.28.camel@lappy>
Date:	Thu, 28 Feb 2008 11:19:46 +0100
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Max Krasnyanskiy <maxk@...lcomm.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	Oleg Nesterov <oleg@...sign.ru>,
	Steven Rostedt <rostedt@...dmis.org>,
	Paul Jackson <pj@....com>, linux-kernel@...r.kernel.org
Subject: Re: [RFC/PATCH 3/4] genirq: system set irq affinities


On Wed, 2008-02-27 at 16:10 -0800, Max Krasnyanskiy wrote:
> Besides the notifier stuff it's identical to my genirq patch that I sent to 
> Thomas and you for the review ~5 days ago.
> There are a couple of things you missed.

Or left out because I didn't take time to actually look at the code to
much. It took me ~4 hours to whip this up (then a few more to debug and
test it).

You missed the call to set_balance_irq_affinity() and went poking in the
balancer itself. 

> Current call site for select_smp_affinity() inside request_irq() is incorrect. 
> It ends up moving irq each time requires_irq() is called, and it is called 
> multiple times for the shared irqs. My patch moves it into setup_irq() under 
> if(!shared) check.

I'll leave that to tglx and mingo and claim lack of clue.

> Also the following part is unsafe
> 
> > +#ifdef CONFIG_CPUSETS
> > +static int system_irq_notifier(struct notifier_block *nb,
> > +		unsigned long action, void *cpus)
> > +{
> > +	cpumask_t *new_system_map = (cpumask_t *)cpus;
> > +	int i;
> > +
> > +	for (i = 0; i < NR_IRQS; i++) {
> > +		struct irq_desc *desc = &irq_desc[i];
> > +
> > +		if (desc->chip == &no_irq_chip || !irq_can_set_affinity(i))
> > +			continue;
> > +
> > +		if (cpus_match_system(desc->affinity)) {
> > +			cpumask_t online_system;
> > +
> > +			cpus_and(online_system, new_system_map, cpu_online_map);
> > +
> > +			set_balance_irq_affinity(i, online_system);
> > +
> > +			desc->affinity = online_system;
> > +			desc->chip->set_affinity(i, online_system);
> Two lines above should be
> 	irq_set_affinity(i, online_system);
> 
> If you look at how irq_set_affinity() is implemented, you'll see this
> 
> #ifdef CONFIG_GENERIC_PENDING_IRQ
>          set_pending_irq(irq, cpumask);
> #else
>          desc->affinity = cpumask;
>          desc->chip->set_affinity(irq, cpumask);
> #endif
> 
> set_pending_irq() is the safe way to move pending irqs.

Seems not unsafe, just not handling pending irqs.




--
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/