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Commit 592903cd authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf_counter: add an event_list 



I noticed that the counter_list only includes top-level counters, thus
perf_swcounter_event() will miss sw-counters in groups.

Since perf_swcounter_event() also wants an RCU safe list, create a new
event_list that includes all counters and uses RCU list ops and use call_rcu
to free the counter structure.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent d6d020e9

include/linux/perf_counter.h

+4 −0
Original line number Diff line number Diff line
@@ -187,6 +187,7 @@ struct file; 
struct perf_counter {

#ifdef CONFIG_PERF_COUNTERS

	struct list_head		list_entry;

	struct list_head		event_entry;

	struct list_head		sibling_list;

	struct perf_counter		*group_leader;

	const struct hw_perf_counter_ops *hw_ops;
@@ -220,6 +221,8 @@ struct perf_counter { 
	struct perf_data		*irqdata;

	struct perf_data		*usrdata;

	struct perf_data		data[2];



	struct rcu_head			rcu_head;

#endif

};
@@ -243,6 +246,7 @@ struct perf_counter_context { 
	struct mutex		mutex;



	struct list_head	counter_list;

	struct list_head	event_list;

	int			nr_counters;

	int			nr_active;

	int			is_active;

kernel/perf_counter.c

+19 −11
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#include <linux/perf_counter.h>

#include <linux/mm.h>

#include <linux/vmstat.h>

#include <linux/rculist.h>



/*

 * Each CPU has a list of per CPU counters:
@@ -72,6 +73,8 @@ list_add_counter(struct perf_counter *counter, struct perf_counter_context *ctx) 
		list_add_tail(&counter->list_entry, &ctx->counter_list);

	else

		list_add_tail(&counter->list_entry, &group_leader->sibling_list);



	list_add_rcu(&counter->event_entry, &ctx->event_list);

}



static void
@@ -80,6 +83,7 @@ list_del_counter(struct perf_counter *counter, struct perf_counter_context *ctx) 
	struct perf_counter *sibling, *tmp;



	list_del_init(&counter->list_entry);

	list_del_rcu(&counter->event_entry);



	/*

	 * If this was a group counter with sibling counters then
@@ -1133,6 +1137,14 @@ static struct perf_counter_context *find_get_context(pid_t pid, int cpu) 
	return ctx;

}



static void free_counter_rcu(struct rcu_head *head)

{

	struct perf_counter *counter;



	counter = container_of(head, struct perf_counter, rcu_head);

	kfree(counter);

}



/*

 * Called when the last reference to the file is gone.

 */
@@ -1151,7 +1163,7 @@ static int perf_release(struct inode *inode, struct file *file) 
	mutex_unlock(&counter->mutex);

	mutex_unlock(&ctx->mutex);



	kfree(counter);

	call_rcu(&counter->rcu_head, free_counter_rcu);

	put_context(ctx);



	return 0;
@@ -1491,22 +1503,16 @@ static void perf_swcounter_ctx_event(struct perf_counter_context *ctx, 
				     int nmi, struct pt_regs *regs)

{

	struct perf_counter *counter;

	unsigned long flags;



	if (list_empty(&ctx->counter_list))

	if (list_empty(&ctx->event_list))

		return;



	spin_lock_irqsave(&ctx->lock, flags);



	/*

	 * XXX: make counter_list RCU safe

	 */

	list_for_each_entry(counter, &ctx->counter_list, list_entry) {

	rcu_read_lock();

	list_for_each_entry_rcu(counter, &ctx->event_list, event_entry) {

		if (perf_swcounter_match(counter, event, regs))

			perf_swcounter_add(counter, nr, nmi, regs);

	}



	spin_unlock_irqrestore(&ctx->lock, flags);

	rcu_read_unlock();

}



void perf_swcounter_event(enum hw_event_types event, u64 nr,
@@ -1846,6 +1852,7 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event, 


	mutex_init(&counter->mutex);

	INIT_LIST_HEAD(&counter->list_entry);

	INIT_LIST_HEAD(&counter->event_entry);

	INIT_LIST_HEAD(&counter->sibling_list);

	init_waitqueue_head(&counter->waitq);
@@ -1992,6 +1999,7 @@ __perf_counter_init_context(struct perf_counter_context *ctx, 
	spin_lock_init(&ctx->lock);

	mutex_init(&ctx->mutex);

	INIT_LIST_HEAD(&ctx->counter_list);

	INIT_LIST_HEAD(&ctx->event_list);

	ctx->task = task;

}