Messages in this thread Patch in this message |  | | Date | Sat, 15 Apr 2017 19:01:23 +0200 | From | Thomas Gleixner <> | Subject | [patch 16/20] perf/x86/intel: Drop get_online_cpus() in intel_snb_check_microcode() |
| |
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
If intel_snb_check_microcode() is invoked via microcode_init -> perf_check_microcode -> intel_snb_check_microcode
then get_online_cpus() is invoked nested. This works with the current implementation of get_online_cpus() but prevents converting it to a percpu rwsem.
intel_snb_check_microcode() is also invoked from intel_sandybridge_quirk() unprotected.
Drop get_online_cpus() from intel_snb_check_microcode() and add it to intel_sandybridge_quirk() so both call sites are protected.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: x86@kernel.org
--- arch/x86/events/intel/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -3389,12 +3389,10 @@ static void intel_snb_check_microcode(vo int pebs_broken = 0; int cpu; - get_online_cpus(); for_each_online_cpu(cpu) { if ((pebs_broken = intel_snb_pebs_broken(cpu))) break; } - put_online_cpus(); if (pebs_broken == x86_pmu.pebs_broken) return; @@ -3467,7 +3465,9 @@ static bool check_msr(unsigned long msr, static __init void intel_sandybridge_quirk(void) { x86_pmu.check_microcode = intel_snb_check_microcode; + get_online_cpus(); intel_snb_check_microcode(); + put_online_cpus(); } static const struct { int id; char *name; } intel_arch_events_map[] __initconst = {
|  |