x86 / perf: Fix suspend to RAM on HP nx6325
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From: Peter Zijlstra on 20 Mar 2010 13:40 On Sat, 2010-03-20 at 15:07 +0100, Rafael J. Wysocki wrote: > Hi Peter, > > Your commit 3f6da3905398826d85731247e7fbcf53400c18bd > (perf: Rework and fix the arch CPU-hotplug hooks) unfortunately broke suspend > to RAM (probably hibernation too, but I haven't checked) on my HP nx6325. > I also expect more (if not all) AMD-based boxes to be broken by it. > > The machine simply hangs solid while trying to disable CPU1 during suspend. > > The patch below fixes it, although I'm not exactly sure why calling > amd_pmu_cpu_offline() during suspend causes the hang to happen. If there's a > better way to fix this, please let me know. Hrmm, I'll have a poke at my AMD once I'm back home again, but does something like the below cure things for you? --- arch/x86/kernel/cpu/perf_event_amd.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event_amd.c b/arch/x86/kernel/cpu/perf_event_amd.c index 358a8e3..0189af4 100644 --- a/arch/x86/kernel/cpu/perf_event_amd.c +++ b/arch/x86/kernel/cpu/perf_event_amd.c @@ -345,6 +345,8 @@ static void amd_pmu_cpu_offline(int cpu) return; cpuhw = &per_cpu(cpu_hw_events, cpu); + if (!cpuhw) + return; raw_spin_lock(&amd_nb_lock); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Peter Zijlstra on 20 Mar 2010 21:20 On Sat, 2010-03-20 at 21:48 +0100, Rafael J. Wysocki wrote: > On Saturday 20 March 2010, Linus Torvalds wrote: > > > > On Sat, 20 Mar 2010, Peter Zijlstra wrote: > > > > > > cpuhw = &per_cpu(cpu_hw_events, cpu); > > > + if (!cpuhw) > > > + return; > > > > How can an address-of expression be NULL? > > > > Yes, 'per_cpu()' is magic, but it shouldn't be possible to be _that_ > > magic. It's rather against the whole C model. > > Yeah. > > A field in the object pointed to by it can be NULL, though. That's what I was aiming for,. might have missed it by a mile though :/ > The appended patch fixes the breakage for me too. ok, works for me, thanks -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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