Subject: Re: [PATCH v2 18/19] ARC: [plat-eznps] replace sync with proper cpu
 barrier
To: Peter Zijlstra <peterz@infradead.org>
References: <1446297327-16298-1-git-send-email-noamc@ezchip.com>
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 <564B0BB1.8080709@synopsys.com>
 <20151117112343.GW3816@twins.programming.kicks-ass.net>
 <564B1182.7050107@synopsys.com>
 <20151117122208.GX3816@twins.programming.kicks-ass.net>
CC: <gilf@ezchip.com>, <talz@ezchip.com>, <linux-kernel@vger.kernel.org>,
        <cmetcalf@ezchip.com>, Noam Camus <noamc@ezchip.com>,
        <linux-snps-arc@lists.infradead.org>
Newsgroups: gmane.linux.kernel.arc,gmane.linux.kernel
From: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Message-ID: <564B1F74.6090709@synopsys.com>
Date: Tue, 17 Nov 2015 18:07:08 +0530
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On Tuesday 17 November 2015 05:52 PM, Peter Zijlstra wrote:
>> > BTW since we are on the topic we have this loop in stack unwinder which can
>> > potentially cause RCU stalls, actual lockups etc. I was planning to add the
>> > following - does that seem fine to you.
> Worries me more than anything. How could you get stuck in there?

No we not getting stuck in there - but this has potential to - if say unwind info
were corrupt (not seen that ever though).

The old code won't even respond to say a Ctrl+C if it were stuck !
Plus the reschedule there will keeps sched happy when say unraveling deep stack
frames with perf ?


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