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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Sebastian Siewior <bigeasy@linutronix.de>,
	Paul McKenney <paulmck@linux.vnet.ibm.com>,
	Borislav Petkov <bp@suse.de>, Borislav Petkov <bp@alien8.de>
Subject: [patch V3 19/32] perf/x86/intel: Drop get_online_cpus() in intel_snb_check_microcode()
Date: Wed, 24 May 2017 10:15:30 +0200
Message-ID: <20170524081548.594862191@linutronix.de> (raw)
In-Reply-To: <20170524081511.203800767@linutronix.de>


[-- Attachment #0: perfx86intel_Drop_get_online_cpus_in_intel_snb_check_microcode.patch --]
[-- Type: text/plain, Size: 2032 bytes --]

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.

Convert *_online_cpus() to the new interfaces while at it.

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>

---
 arch/x86/events/intel/core.c |   11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -3410,12 +3410,10 @@ 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;
@@ -3488,7 +3486,9 @@ static bool check_msr(unsigned long msr,
 static __init void intel_sandybridge_quirk(void)
 {
 	x86_pmu.check_microcode = intel_snb_check_microcode;
+	cpus_read_lock();
 	intel_snb_check_microcode();
+	cpus_read_unlock();
 }
 
 static const struct { int id; char *name; } intel_arch_events_map[] __initconst = {
@@ -4112,13 +4112,12 @@ static __init int fixup_ht_bug(void)
 
 	lockup_detector_resume();
 
-	get_online_cpus();
+	cpus_read_lock();
 
-	for_each_online_cpu(c) {
+	for_each_online_cpu(c)
 		free_excl_cntrs(c);
-	}
 
-	put_online_cpus();
+	cpus_read_unlock();
 	pr_info("PMU erratum BJ122, BV98, HSD29 workaround disabled, HT off\n");
 	return 0;
 }

  parent reply index

Thread overview: 82+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-24  8:15 [patch V3 00/32] cpu/hotplug: Convert get_online_cpus() to a percpu_rwsem Thomas Gleixner
2017-05-24  8:15 ` [patch V3 01/32] cpu/hotplug: Provide cpus_read|write_[un]lock() Thomas Gleixner
2017-05-24 16:25   ` Paul E. McKenney
2017-05-26  8:31   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 02/32] cpu/hotplug: Provide lockdep_assert_cpus_held() Thomas Gleixner
2017-05-24 16:26   ` Paul E. McKenney
2017-05-26  8:32   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 03/32] cpu/hotplug: Provide cpuhp_setup/remove_state[_nocalls]_cpuslocked() Thomas Gleixner
2017-05-26  8:32   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 04/32] cpu/hotplug: Add __cpuhp_state_add_instance_cpuslocked() Thomas Gleixner
2017-05-26  8:33   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 05/32] stop_machine: Provide stop_machine_cpuslocked() Thomas Gleixner
2017-05-24 17:42   ` Paul E. McKenney
2017-05-26  8:33   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 06/32] padata: Make padata_alloc() static Thomas Gleixner
2017-05-26  8:34   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 07/32] padata: Avoid nested calls to cpus_read_lock() in pcrypt_init_padata() Thomas Gleixner
2017-05-26  8:35   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 08/32] x86/mtrr: Remove get_online_cpus() from mtrr_save_state() Thomas Gleixner
2017-05-26  8:35   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 09/32] cpufreq: Use cpuhp_setup_state_nocalls_cpuslocked() Thomas Gleixner
2017-05-26  8:36   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 10/32] KVM/PPC/Book3S HV: " Thomas Gleixner
2017-05-26  8:36   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 11/32] hwtracing/coresight-etm3x: " Thomas Gleixner
2017-05-25 16:46   ` Mathieu Poirier
2017-05-26  8:37   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 12/32] hwtracing/coresight-etm4x: " Thomas Gleixner
2017-05-25 16:47   ` Mathieu Poirier
2017-05-26  8:37   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 13/32] perf/x86/intel/cqm: Use cpuhp_setup_state_cpuslocked() Thomas Gleixner
2017-05-26  8:38   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 14/32] ARM/hw_breakpoint: " Thomas Gleixner
2017-05-26  8:38   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 15/32] s390/kernel: Use stop_machine_cpuslocked() Thomas Gleixner
2017-05-24 10:57   ` Heiko Carstens
2017-05-26  8:39   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 16/32] powerpc/powernv: " Thomas Gleixner
2017-05-26  8:40   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 17/32] cpu/hotplug: Use stop_machine_cpuslocked() in takedown_cpu() Thomas Gleixner
2017-05-26  8:40   ` [tip:smp/hotplug] " tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 18/32] x86/perf: Drop EXPORT of perf_check_microcode Thomas Gleixner
2017-05-26  8:41   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` Thomas Gleixner [this message]
2017-05-26  8:41   ` [tip:smp/hotplug] perf/x86/intel: Drop get_online_cpus() in intel_snb_check_microcode() tip-bot for Sebastian Andrzej Siewior
2017-05-24  8:15 ` [patch V3 20/32] PCI: Use cpu_hotplug_disable() instead of get_online_cpus() Thomas Gleixner
2017-05-26  8:42   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 21/32] PCI: Replace the racy recursion prevention Thomas Gleixner
2017-05-26  8:42   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 22/32] ACPI/processor: Use cpu_hotplug_disable() instead of get_online_cpus() Thomas Gleixner
2017-05-26  8:43   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 23/32] perf/tracing/cpuhotplug: Fix locking order Thomas Gleixner
2017-05-24 18:30   ` Paul E. McKenney
2017-05-24 18:47     ` Thomas Gleixner
2017-05-24 21:10       ` Paul E. McKenney
2017-05-30 11:22     ` Peter Zijlstra
2017-05-30 16:25       ` Paul E. McKenney
2017-05-26  8:43   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 24/32] jump_label: Reorder hotplug lock and jump_label_lock Thomas Gleixner
2017-05-24 12:50   ` David Miller
2017-05-26  8:44   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 25/32] kprobes: Cure hotplug lock ordering issues Thomas Gleixner
2017-05-24 15:54   ` Masami Hiramatsu
2017-05-26  7:47     ` Thomas Gleixner
2017-05-26  8:45   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 26/32] arm64: Prevent cpu hotplug rwsem recursion Thomas Gleixner
2017-05-26  8:45   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 27/32] arm: Prevent " Thomas Gleixner
2017-05-26  8:46   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 28/32] s390: " Thomas Gleixner
2017-05-24 10:57   ` Heiko Carstens
2017-05-26  8:46   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 29/32] cpu/hotplug: Convert hotplug locking to percpu rwsem Thomas Gleixner
2017-05-26  8:47   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 30/32] sched: Provide is_percpu_thread() helper Thomas Gleixner
2017-05-26  8:47   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 31/32] acpi/processor: Prevent cpu hotplug deadlock Thomas Gleixner
2017-05-26  8:48   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24  8:15 ` [patch V3 32/32] cpuhotplug: Link lock stacks for hotplug callbacks Thomas Gleixner
2017-05-26  8:48   ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2017-05-24 16:22 ` [patch V3 00/32] cpu/hotplug: Convert get_online_cpus() to a percpu_rwsem Paul E. McKenney
2017-05-26  7:03 ` Ingo Molnar

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