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Commit 7fdba1ca authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf, x86: Avoid kfree() in CPU_STARTING 



On -rt kfree() can schedule, but CPU_STARTING is before the CPU is
fully up and running. These are contradictory, so avoid it. Instead
push the kfree() to CPU_ONLINE where we're free to schedule.

Reported-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-kwd4j6ayld5thrscvaxgjquv@git.kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent bdc2209f

arch/x86/kernel/cpu/perf_event.c

+8 −0
Original line number Diff line number Diff line
@@ -129,6 +129,8 @@ struct cpu_hw_events { 
	 * AMD specific bits

	 */

	struct amd_nb		*amd_nb;



	void			*kfree_on_online;

};



#define __EVENT_CONSTRAINT(c, n, m, w) {\
@@ -1466,10 +1468,12 @@ static int __cpuinit 
x86_pmu_notifier(struct notifier_block *self, unsigned long action, void *hcpu)

{

	unsigned int cpu = (long)hcpu;

	struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu);

	int ret = NOTIFY_OK;



	switch (action & ~CPU_TASKS_FROZEN) {

	case CPU_UP_PREPARE:

		cpuc->kfree_on_online = NULL;

		if (x86_pmu.cpu_prepare)

			ret = x86_pmu.cpu_prepare(cpu);

		break;
@@ -1479,6 +1483,10 @@ x86_pmu_notifier(struct notifier_block *self, unsigned long action, void *hcpu) 
			x86_pmu.cpu_starting(cpu);

		break;



	case CPU_ONLINE:

		kfree(cpuc->kfree_on_online);

		break;



	case CPU_DYING:

		if (x86_pmu.cpu_dying)

			x86_pmu.cpu_dying(cpu);

arch/x86/kernel/cpu/perf_event_amd.c

+1 −1
Original line number Diff line number Diff line
@@ -350,7 +350,7 @@ static void amd_pmu_cpu_starting(int cpu) 
			continue;



		if (nb->nb_id == nb_id) {

			kfree(cpuc->amd_nb);

			cpuc->kfree_on_online = cpuc->amd_nb;

			cpuc->amd_nb = nb;

			break;

		}

arch/x86/kernel/cpu/perf_event_intel.c

+1 −1
Original line number Diff line number Diff line
@@ -1362,7 +1362,7 @@ static void intel_pmu_cpu_starting(int cpu) 


		pc = per_cpu(cpu_hw_events, i).shared_regs;

		if (pc && pc->core_id == core_id) {

			kfree(cpuc->shared_regs);

			cpuc->kfree_on_online = cpuc->shared_regs;

			cpuc->shared_regs = pc;

			break;

		}