linux-kernel - Re: CPU hotplug and chained interrupts on x86

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] [day] [month] [year] [list]

Message-ID: <20151002045839.GR1551@lahna.fi.intel.com>
Date:	Fri, 2 Oct 2015 07:58:39 +0300
From:	Mika Westerberg <mika.westerberg@...ux.intel.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Jiang Liu <jiang.liu@...ux.intel.com>, linux-kernel@...r.kernel.org
Subject: Re: CPU hotplug and chained interrupts on x86

On Thu, Oct 01, 2015 at 11:45:23PM +0200, Thomas Gleixner wrote:
> On Thu, 1 Oct 2015, Thomas Gleixner wrote:
> > On Thu, 1 Oct 2015, Mika Westerberg wrote:
> > > Now if I plug/unplug the card I may get few interrupts to CPU0 but rest
> > > of the interrupts never happen. Probably because IO-APIC forwards them
> > > to the lowest priority CPU which is offline at this point.
> > > 
> > > There is following check in fixup_irqs():
> > > 
> > > 	if (!irq_has_action(irq) || irqd_is_per_cpu(data) ||
> > > 	    cpumask_subset(affinity, cpu_online_mask)) {
> > > 		raw_spin_unlock(&desc->lock);
> > > 		continue;
> > > 	}   
> > > 
> > > If an interrupt is requested by a driver it will force new affinity and
> > > everything works fine. However if the interrupt is chained (it does not
> > > have ->action) this is skipped and the current affinity remains.
> > > 
> > > We could detect here if the interrupt is chained but there seems to be
> > > no easy way to determine it currently so we would need to add a new flag
> > > to desc->status_use_accessors that gets set in __irq_do_set_handler()
> > > when is_chained is 1.
> > 
> > Either there or in irq_data. Need to look at it in detail.
> 
> desc->status_use_accessors is the place where this wants to go.

Thank you.

I'll prepare a patch fixing this shortly.
--
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/