From: Vineet Gupta <vgupta@synopsys.com>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Peter Zijlstra <peterz@infradead.org>,
Will Deacon <Will.Deacon@arm.com>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
Marc Zyngier <marc.zyngier@arm.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
lkml <linux-kernel@vger.kernel.org>,
Noam Camus <noamc@ezchip.com>,
arcml <linux-snps-arc@lists.infradead.org>
Subject: Re: Interesting csd deadlock on ARC
Date: Thu, 25 Feb 2016 21:28:02 +0530 [thread overview]
Message-ID: <56CF248A.3070805@synopsys.com> (raw)
In-Reply-To: <20160225143046.GR19428@n2100.arm.linux.org.uk>
On Thursday 25 February 2016 08:00 PM, Russell King - ARM Linux wrote:
> On Thu, Feb 25, 2016 at 07:53:39PM +0530, Vineet Gupta wrote:
>> But then ARM CONFIG_SMP on UP hardware will still crap out because there
>> is no way to send IPI to self. Same as the bug in above discussion. I'm
>> surprised they way ARM guys worked around it.
>
> We haven't worked around it - the code which provoked the oops that was
> seen (in the cpufreq code) was changed not to call it, which has the
> effect of making the problem "go away", at least for now.
>
> We still have the problem that if it does get called on UP, it'll blow
> up - and I don't see any point in complicating the code for something
> that never happens right now.
Right so my statement "workaround" was technically incorrect. But like you say,
it's a ticking bomb which will certainly go off on your SMP on UP systems the
moment someone adds irq_work_queue_on() in some obscure corner of generic code.
And I think this merits fixing in generic code !
-Vineet
prev parent reply other threads:[~2016-02-25 15:58 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-19 6:47 Interesting csd deadlock on ARC Vineet Gupta
2016-02-23 5:21 ` Vineet Gupta
2016-02-23 9:58 ` Peter Zijlstra
2016-02-23 10:21 ` Vineet Gupta
2016-02-23 10:39 ` Peter Zijlstra
2016-02-23 10:58 ` Noam Camus
2016-02-24 4:45 ` Vineet Gupta
2016-02-24 4:51 ` Vineet Gupta
2016-02-25 14:06 ` Peter Zijlstra
2016-02-25 14:23 ` Vineet Gupta
2016-02-25 14:30 ` Russell King - ARM Linux
2016-02-25 15:58 ` Vineet Gupta [this message]
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