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Commit 1dce8d99 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

perf_counter: convert perf_resource_mutex to a spinlock 



Now percpu counters can be initialized very early. But the init
sequence uses mutex_lock(). Fortunately, perf_resource_mutex should
be a spinlock anyway, so convert it.

[ Impact: fix crash due to early init mutex use ]

LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 0d905bca

kernel/perf_counter.c

+8 −8
Original line number Diff line number Diff line
@@ -46,9 +46,9 @@ static atomic_t nr_comm_tracking __read_mostly; 
int sysctl_perf_counter_priv __read_mostly; /* do we need to be privileged */



/*

 * Mutex for (sysadmin-configurable) counter reservations:

 * Lock for (sysadmin-configurable) counter reservations:

 */

static DEFINE_MUTEX(perf_resource_mutex);

static DEFINE_SPINLOCK(perf_resource_lock);



/*

 * Architecture provided APIs - weak aliases:
@@ -3207,9 +3207,9 @@ static void __cpuinit perf_counter_init_cpu(int cpu) 
	cpuctx = &per_cpu(perf_cpu_context, cpu);

	__perf_counter_init_context(&cpuctx->ctx, NULL);



	mutex_lock(&perf_resource_mutex);

	spin_lock(&perf_resource_lock);

	cpuctx->max_pertask = perf_max_counters - perf_reserved_percpu;

	mutex_unlock(&perf_resource_mutex);

	spin_unlock(&perf_resource_lock);



	hw_perf_counter_setup(cpu);

}
@@ -3292,7 +3292,7 @@ perf_set_reserve_percpu(struct sysdev_class *class, 
	if (val > perf_max_counters)

		return -EINVAL;



	mutex_lock(&perf_resource_mutex);

	spin_lock(&perf_resource_lock);

	perf_reserved_percpu = val;

	for_each_online_cpu(cpu) {

		cpuctx = &per_cpu(perf_cpu_context, cpu);
@@ -3302,7 +3302,7 @@ perf_set_reserve_percpu(struct sysdev_class *class, 
		cpuctx->max_pertask = mpt;

		spin_unlock_irq(&cpuctx->ctx.lock);

	}

	mutex_unlock(&perf_resource_mutex);

	spin_unlock(&perf_resource_lock);



	return count;

}
@@ -3324,9 +3324,9 @@ perf_set_overcommit(struct sysdev_class *class, const char *buf, size_t count) 
	if (val > 1)

		return -EINVAL;



	mutex_lock(&perf_resource_mutex);

	spin_lock(&perf_resource_lock);

	perf_overcommit = val;

	mutex_unlock(&perf_resource_mutex);

	spin_unlock(&perf_resource_lock);



	return count;

}