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Commit 3df5edad authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf_counter: rework ioctl()s 



Corey noticed that ioctl()s on grouped counters didn't work on
the whole group. This extends the ioctl() interface to take a
second argument that is interpreted as a flags field. We then
provide PERF_IOC_FLAG_GROUP to toggle the behaviour.

Having this flag gives the greatest flexibility, allowing you
to individually enable/disable/reset counters in a group, or
all together.

[ Impact: fix group counter enable/disable semantics ]

Reported-by: default avatarCorey Ashford <cjashfor@linux.vnet.ibm.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20090508170028.837558214@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 7fc23a53

include/linux/perf_counter.h

+7 −3
Original line number Diff line number Diff line
@@ -157,10 +157,14 @@ struct perf_counter_hw_event { 
/*

 * Ioctls that can be done on a perf counter fd:

 */

#define PERF_COUNTER_IOC_ENABLE		_IO ('$', 0)

#define PERF_COUNTER_IOC_DISABLE	_IO ('$', 1)

#define PERF_COUNTER_IOC_ENABLE		_IOW('$', 0, u32)

#define PERF_COUNTER_IOC_DISABLE	_IOW('$', 1, u32)

#define PERF_COUNTER_IOC_REFRESH	_IOW('$', 2, u32)

#define PERF_COUNTER_IOC_RESET		_IO ('$', 3)

#define PERF_COUNTER_IOC_RESET		_IOW('$', 3, u32)



enum perf_counter_ioc_flags {

	PERF_IOC_FLAG_GROUP		= 1U << 0,

};



/*

 * Structure of the page that can be mapped via mmap

kernel/perf_counter.c

+58 −46
Original line number Diff line number Diff line
@@ -82,7 +82,7 @@ list_add_counter(struct perf_counter *counter, struct perf_counter_context *ctx) 
	 * add it straight to the context's counter list, or to the group

	 * leader's sibling list:

	 */

	if (counter->group_leader == counter)

	if (group_leader == counter)

		list_add_tail(&counter->list_entry, &ctx->counter_list);

	else {

		list_add_tail(&counter->list_entry, &group_leader->sibling_list);
@@ -385,24 +385,6 @@ static void perf_counter_disable(struct perf_counter *counter) 
	spin_unlock_irq(&ctx->lock);

}



/*

 * Disable a counter and all its children.

 */

static void perf_counter_disable_family(struct perf_counter *counter)

{

	struct perf_counter *child;



	perf_counter_disable(counter);



	/*

	 * Lock the mutex to protect the list of children

	 */

	mutex_lock(&counter->mutex);

	list_for_each_entry(child, &counter->child_list, child_list)

		perf_counter_disable(child);

	mutex_unlock(&counter->mutex);

}



static int

counter_sched_in(struct perf_counter *counter,

		 struct perf_cpu_context *cpuctx,
@@ -753,24 +735,6 @@ static int perf_counter_refresh(struct perf_counter *counter, int refresh) 
	return 0;

}



/*

 * Enable a counter and all its children.

 */

static void perf_counter_enable_family(struct perf_counter *counter)

{

	struct perf_counter *child;



	perf_counter_enable(counter);



	/*

	 * Lock the mutex to protect the list of children

	 */

	mutex_lock(&counter->mutex);

	list_for_each_entry(child, &counter->child_list, child_list)

		perf_counter_enable(child);

	mutex_unlock(&counter->mutex);

}



void __perf_counter_sched_out(struct perf_counter_context *ctx,

			      struct perf_cpu_context *cpuctx)

{
@@ -1307,31 +1271,79 @@ static unsigned int perf_poll(struct file *file, poll_table *wait) 


static void perf_counter_reset(struct perf_counter *counter)

{

	(void)perf_counter_read(counter);

	atomic_set(&counter->count, 0);

	perf_counter_update_userpage(counter);

}



static void perf_counter_for_each_sibling(struct perf_counter *counter,

					  void (*func)(struct perf_counter *))

{

	struct perf_counter_context *ctx = counter->ctx;

	struct perf_counter *sibling;



	spin_lock_irq(&ctx->lock);

	counter = counter->group_leader;



	func(counter);

	list_for_each_entry(sibling, &counter->sibling_list, list_entry)

		func(sibling);

	spin_unlock_irq(&ctx->lock);

}



static void perf_counter_for_each_child(struct perf_counter *counter,

					void (*func)(struct perf_counter *))

{

	struct perf_counter *child;



	mutex_lock(&counter->mutex);

	func(counter);

	list_for_each_entry(child, &counter->child_list, child_list)

		func(child);

	mutex_unlock(&counter->mutex);

}



static void perf_counter_for_each(struct perf_counter *counter,

				  void (*func)(struct perf_counter *))

{

	struct perf_counter *child;



	mutex_lock(&counter->mutex);

	perf_counter_for_each_sibling(counter, func);

	list_for_each_entry(child, &counter->child_list, child_list)

		perf_counter_for_each_sibling(child, func);

	mutex_unlock(&counter->mutex);

}



static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)

{

	struct perf_counter *counter = file->private_data;

	int err = 0;

	void (*func)(struct perf_counter *);

	u32 flags = arg;



	switch (cmd) {

	case PERF_COUNTER_IOC_ENABLE:

		perf_counter_enable_family(counter);

		func = perf_counter_enable;

		break;

	case PERF_COUNTER_IOC_DISABLE:

		perf_counter_disable_family(counter);

		break;

	case PERF_COUNTER_IOC_REFRESH:

		err = perf_counter_refresh(counter, arg);

		func = perf_counter_disable;

		break;

	case PERF_COUNTER_IOC_RESET:

		perf_counter_reset(counter);

		func = perf_counter_reset;

		break;



	case PERF_COUNTER_IOC_REFRESH:

		return perf_counter_refresh(counter, arg);

	default:

		err = -ENOTTY;

		return -ENOTTY;

	}

	return err;



	if (flags & PERF_IOC_FLAG_GROUP)

		perf_counter_for_each(counter, func);

	else

		perf_counter_for_each_child(counter, func);



	return 0;

}



/*