Commit-ID: 494d8679788930b29e1262d92db4c1912bdf9119 Gitweb: http://git.kernel.org/tip/494d8679788930b29e1262d92db4c1912bdf9119 Author: Sebastian Andrzej Siewior <[email protected]> AuthorDate: Tue, 18 Apr 2017 19:04:58 +0200 Committer: Thomas Gleixner <[email protected]> CommitDate: Thu, 20 Apr 2017 13:08:55 +0200
perf/x86/intel: Drop get_online_cpus() in intel_snb_check_microcode() 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 <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Acked-by: Borislav Petkov <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Borislav Petkov <[email protected]> Link: http://lkml.kernel.org/r/[email protected] --- arch/x86/events/intel/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index eb1484c..152b7e4 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -3389,12 +3389,10 @@ static void intel_snb_check_microcode(void) 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, u64 mask) 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 = {
