Messages in this thread | | | Date | Fri, 3 Sep 2010 00:36:08 +0400 | From | Cyrill Gorcunov <> | Subject | Re: [PATCH 1/3] perf, x86: Fix accidentally ack'ing a second event on intel perf counter |
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On Thu, Sep 02, 2010 at 04:00:21PM -0400, Don Zickus wrote: > On Thu, Sep 02, 2010 at 11:26:27PM +0400, Cyrill Gorcunov wrote: > > Lets assume 1 counters is triggered and global bit is set as well > > > > we have here > > > > status = intel_pmu_get_status(); > > > > > perf_sample_data_init(&data, 0); > > > > > > @@ -728,6 +728,7 @@ static int intel_pmu_handle_irq(struct pt_regs *regs) > > > > > > loops = 0; > > > again: > > > + intel_pmu_ack_status(status); > > > > So here we write just being read value back to CTRL register and _if_ new > > overflow happened in this window we've cleared it without processing. > > No, you have to write a '1' to clear. If a new bit is set after we read > it, then our 'status' var should have a '0' in that bit and thus will not > get cleared when we ack it. >
Yeah, messed {0;1} values, thanks!
> Cheers, > Don > -- Cyrill
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