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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: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-03-13 12:21:36 +01:00 committed by Ingo Molnar
parent d6d020e995
commit 592903cdcb
2 changed files with 23 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/linux/perf_counter.h
View File

@ -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;

30
kernel/perf_counter.c
View File

@ -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;
}