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Groups > linux.kernel > #1627389

[tip:smp/hotplug] perf/x86/intel: Drop get_online_cpus() in intel_snb_check_microcode()

From tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com>
Newsgroups linux.kernel
Subject [tip:smp/hotplug] perf/x86/intel: Drop get_online_cpus() in intel_snb_check_microcode()
Date 2017-04-20 13:40 +0200
Message-ID <tyiBk-8mU-29@gated-at.bofh.it> (permalink)
References <txHs6-1Kl-9@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Commit-ID:  494d8679788930b29e1262d92db4c1912bdf9119
Gitweb:     http://git.kernel.org/tip/494d8679788930b29e1262d92db4c1912bdf9119
Author:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
AuthorDate: Tue, 18 Apr 2017 19:04:58 +0200
Committer:  Thomas Gleixner <tglx@linutronix.de>
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 <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/20170418170553.713742599@linutronix.de

---
 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 = {

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Thread

[patch V2 00/24] cpu/hotplug: Convert get_online_cpus() to a  percpu_rwsem Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 21:50 +0200
  [patch V2 03/24] padata: Make padata_alloc() static Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 21:50 +0200
    [tip:smp/hotplug] padata: Make padata_alloc() static tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-20 13:30 +0200
  [patch V2 20/24] perf/core: Remove redundant get_online_cpus() Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
    [tip:smp/hotplug] perf/core: Remove redundant get_online_cpus() tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-20 13:40 +0200
  [patch V2 22/24] jump_label: Provide static_key_slow_inc_cpuslocked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
  [patch V2 15/24] x86/perf: Drop EXPORT of perf_check_microcode Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
    [tip:smp/hotplug] x86/perf: Drop EXPORT of perf_check_microcode tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-20 13:30 +0200
  [patch V2 09/24] hwtracing/coresight-etm4x: Use  cpuhp_setup_state_nocalls_cpuslocked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
    [tip:smp/hotplug] hwtracing/coresight-etm4x: Use  cpuhp_setup_state_nocalls_cpuslocked() tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2017-04-20 13:30 +0200
  [patch V2 23/24] perf: Avoid cpu_hotplug_lock r-r recursion Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
  [patch V2 16/24] perf/x86/intel: Drop get_online_cpus() in  intel_snb_check_microcode() Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
    [tip:smp/hotplug] perf/x86/intel: Drop get_online_cpus() in  intel_snb_check_microcode() tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2017-04-20 13:40 +0200
  [patch V2 24/24] cpu/hotplug: Convert hotplug locking to percpu rwsem Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
    [tip:smp/hotplug] cpu/hotplug: Convert hotplug locking to percpu  rwsem tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-20 13:40 +0200
  [patch V2 05/24] x86/mtrr: Remove get_online_cpus() from  mtrr_save_state() Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
    [tip:smp/hotplug] x86/mtrr: Remove get_online_cpus() from  mtrr_save_state() tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2017-04-20 13:30 +0200
  [patch V2 14/24] cpu/hotplug: Use stop_machine_cpuslocked() in  takedown_cpu() Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
    [tip:smp/hotplug] cpu/hotplug: Use stop_machine_cpuslocked() in  takedown_cpu() tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2017-04-20 13:30 +0200
  [patch V2 18/24] PCI: Replace the racy recursion prevention Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
    [tip:smp/hotplug] PCI: Replace the racy recursion prevention tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-20 13:40 +0200
  [patch V2 21/24] jump_label: Pull get_online_cpus() into generic code Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
  [patch V2 12/24] s390/kernel: Use stop_machine_cpuslocked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
    [tip:smp/hotplug] s390/kernel: Use stop_machine_cpuslocked() tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2017-04-20 13:30 +0200
  [patch V2 06/24] cpufreq: Use cpuhp_setup_state_nocalls_cpuslocked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
    [tip:smp/hotplug] cpufreq: Use  cpuhp_setup_state_nocalls_cpuslocked() tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2017-04-20 13:30 +0200
  [patch V2 19/24] ACPI/processor: Use cpu_hotplug_disable() instead of  get_online_cpus() Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
    [tip:smp/hotplug] ACPI/processor: Use cpu_hotplug_disable() instead  of get_online_cpus() tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-20 13:40 +0200
  [patch V2 08/24] hwtracing/coresight-etm3x: Use  cpuhp_setup_state_nocalls_cpuslocked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
    [tip:smp/hotplug] hwtracing/coresight-etm3x: Use  cpuhp_setup_state_nocalls_cpuslocked() tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2017-04-20 13:30 +0200
    Re: [patch V2 08/24] hwtracing/coresight-etm3x: Use cpuhp_setup_state_nocalls_cpuslocked() Mathieu Poirier <mathieu.poirier@linaro.org> - 2017-04-20 17:20 +0200
    Re: [patch V2 08/24] hwtracing/coresight-etm3x: Use  cpuhp_setup_state_nocalls_cpuslocked() Mathieu Poirier <mathieu.poirier@linaro.org> - 2017-04-20 17:40 +0200
  [patch V2 17/24] PCI: Use cpu_hotplug_disable() instead of  get_online_cpus() Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
    [tip:smp/hotplug] PCI: Use cpu_hotplug_disable() instead of  get_online_cpus() tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-20 13:40 +0200
  [patch V2 13/24] powerpc/powernv: Use stop_machine_cpuslocked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
    [tip:smp/hotplug] powerpc/powernv: Use stop_machine_cpuslocked() tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2017-04-20 13:30 +0200
  [patch V2 11/24] ARM/hw_breakpoint: Use cpuhp_setup_state_cpuslocked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
    Re: [patch V2 11/24] ARM/hw_breakpoint: Use  cpuhp_setup_state_cpuslocked() Mark Rutland <mark.rutland@arm.com> - 2017-04-19 20:00 +0200
      Re: [patch V2 11/24] ARM/hw_breakpoint: Use  cpuhp_setup_state_cpuslocked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-19 20:30 +0200
    [tip:smp/hotplug] ARM/hw_breakpoint: Use  cpuhp_setup_state_cpuslocked() tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2017-04-20 13:30 +0200
  [patch V2 07/24] KVM/PPC/Book3S HV: Use  cpuhp_setup_state_nocalls_cpuslocked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
    [tip:smp/hotplug] KVM/PPC/Book3S HV: Use  cpuhp_setup_state_nocalls_cpuslocked() tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2017-04-20 13:30 +0200
  [patch V2 10/24] perf/x86/intel/cqm: Use  cpuhp_setup_state_cpuslocked() Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 22:00 +0200
    [tip:smp/hotplug] perf/x86/intel/cqm: Use  cpuhp_setup_state_cpuslocked() tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2017-04-20 13:30 +0200

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