From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755640AbdDORbe (ORCPT ); Sat, 15 Apr 2017 13:31:34 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:44502 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754641AbdDORb0 (ORCPT ); Sat, 15 Apr 2017 13:31:26 -0400 Message-Id: <20170415171652.582131508@linutronix.de> User-Agent: quilt/0.63-1 Date: Sat, 15 Apr 2017 19:01:23 +0200 From: Thomas Gleixner To: LKML Cc: Peter Zijlstra , Ingo Molnar , Steven Rostedt , Sebastian Siewior , Borislav Petkov , x86@kernel.org Subject: [patch 16/20] perf/x86/intel: Drop get_online_cpus() in intel_snb_check_microcode() References: <20170415170107.643253702@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Disposition: inline; filename=perfx86intel_Drop_get_online_cpus()_in_intel_snb_check_microcode().patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sebastian Andrzej Siewior 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 Signed-off-by: Thomas Gleixner Cc: Peter Zijlstra Cc: Borislav Petkov 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 = {