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Peter Zijlstra authored
Frederic reported that frequency driven swevents didn't work properly and even caused a division-by-zero error. It turns out there are two bugs, the division-by-zero comes from a failure to deal with that in perf_calculate_period(). The other was more interesting and turned out to be a wrong comparison in perf_adjust_period(). The comparison was between an s64 and u64 and got implicitly converted to an unsigned comparison. The problem is that period_left is typically < 0, so it ended up being always true. Cure this by making the local period variables s64. Reported-by:
Frederic Weisbecker <fweisbec@gmail.com> Tested-by:
Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by:
Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: <stable@kernel.org> LKML-Reference: <new-submission> Signed-off-by:
Ingo Molnar <mingo@elte.hu>
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