Commit 0d905bca authored by Ingo Molnar's avatar Ingo Molnar
Browse files

perf_counter: initialize the per-cpu context earlier 



percpu scheduling for perfcounters wants to take the context lock,
but that lock first needs to be initialized. Currently it is an
early_initcall() - but that is too late, the task tick runs much
sooner than that.

Call it explicitly from the scheduler init sequence instead.

[ Impact: fix access-before-init crash ]

LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent ba77813a

include/linux/perf_counter.h

+4 −1
Original line number Diff line number Diff line
@@ -573,6 +573,8 @@ extern struct perf_callchain_entry *perf_callchain(struct pt_regs *regs); 


extern int sysctl_perf_counter_priv;



extern void perf_counter_init(void);



#else

static inline void

perf_counter_task_sched_in(struct task_struct *task, int cpu)		{ }
@@ -603,6 +605,7 @@ perf_counter_munmap(unsigned long addr, unsigned long len, 
		    unsigned long pgoff, struct file *file)		{ }



static inline void perf_counter_comm(struct task_struct *tsk)		{ }

static inline void perf_counter_init(void)				{ }

#endif



#endif /* __KERNEL__ */

kernel/perf_counter.c

+1 −4
Original line number Diff line number Diff line
@@ -3265,15 +3265,12 @@ static struct notifier_block __cpuinitdata perf_cpu_nb = { 
	.notifier_call		= perf_cpu_notify,

};



static int __init perf_counter_init(void)

void __init perf_counter_init(void)

{

	perf_cpu_notify(&perf_cpu_nb, (unsigned long)CPU_UP_PREPARE,

			(void *)(long)smp_processor_id());

	register_cpu_notifier(&perf_cpu_nb);



	return 0;

}

early_initcall(perf_counter_init);



static ssize_t perf_show_reserve_percpu(struct sysdev_class *class, char *buf)

{

kernel/sched.c

+4 −1
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ 
#include <linux/completion.h>

#include <linux/kernel_stat.h>

#include <linux/debug_locks.h>

#include <linux/perf_counter.h>

#include <linux/security.h>

#include <linux/notifier.h>

#include <linux/profile.h>
@@ -9097,6 +9098,8 @@ void __init sched_init(void) 
	alloc_bootmem_cpumask_var(&cpu_isolated_map);

#endif /* SMP */



	perf_counter_init();



	scheduler_running = 1;

}

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