Messages in this thread | | | Date | Tue, 17 Nov 2015 13:44:21 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v2 18/19] ARC: [plat-eznps] replace sync with proper cpu barrier |
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On Tue, Nov 17, 2015 at 06:07:08PM +0530, Vineet Gupta wrote: > 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).
Better put in a failsafe for that anyway, just out of sheer paranoia :-)
You should never report more than PERF_MAX_STACK_DEPTH thingies anyway, so once you've done that many loops, you're good to bail, right?
> 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 ?
You're likely to call this code from interrupt/NMI context, there is no ^C or scheduling going to help you there.
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