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Subject[PATCH v3 09/12] perf, persistent: Use unique event ids
Date
From: Robert Richter <robert.richter@linaro.org>

Tracepoints have a unique attr.config value. But, this is not
sufficient to support all event types. For this we need to generate
unique event ids.

Signed-off-by: Robert Richter <robert.richter@linaro.org>
Signed-off-by: Robert Richter <rric@kernel.org>
---
kernel/events/persistent.c | 40 ++++++++++++++++++++++++++++++++++++++--
1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/kernel/events/persistent.c b/kernel/events/persistent.c
index aca1e98..f23270b 100644
--- a/kernel/events/persistent.c
+++ b/kernel/events/persistent.c
@@ -1,6 +1,7 @@
#include <linux/slab.h>
#include <linux/perf_event.h>
#include <linux/ftrace_event.h>
+#include <linux/idr.h>

#include "internal.h"

@@ -13,10 +14,37 @@ struct pevent {
int id;
};

+static struct idr event_idr;
+static struct mutex event_lock;
static struct pmu persistent_pmu;
static DEFINE_PER_CPU(struct list_head, pevents);
static DEFINE_PER_CPU(struct mutex, pevents_lock);

+static inline struct pevent *find_event(int id)
+{
+ struct pevent *pevent;
+ rcu_read_lock();
+ pevent = idr_find(&event_idr, id);
+ rcu_read_lock();
+ return pevent;
+}
+
+static inline int get_event_id(struct pevent *pevent)
+{
+ int event_id;
+ mutex_lock(&event_lock);
+ event_id = idr_alloc(&event_idr, pevent, 1, INT_MAX, GFP_KERNEL);
+ mutex_unlock(&event_lock);
+ return event_id;
+}
+
+static inline void put_event_id(int id)
+{
+ mutex_lock(&event_lock);
+ idr_remove(&event_idr, id);
+ mutex_unlock(&event_lock);
+}
+
/* Must be protected with pevents_lock. */
static struct perf_event *__pevent_find(int cpu, int id)
{
@@ -128,13 +156,16 @@ persistent_open(char *name, struct perf_event_attr *attr, int nr_pages)
struct pevent *pevent;
char id_buf[32];
int cpu;
- int ret = 0;
+ int ret;

pevent = kzalloc(sizeof(*pevent), GFP_KERNEL);
if (!pevent)
return -ENOMEM;

- pevent->id = attr->config;
+ ret = get_event_id(pevent);
+ if (ret < 0)
+ goto fail;
+ pevent->id = ret;

if (!name) {
snprintf(id_buf, sizeof(id_buf), "%d", pevent->id);
@@ -163,6 +194,9 @@ persistent_open(char *name, struct perf_event_attr *attr, int nr_pages)
fail:
for_each_possible_cpu(cpu)
persistent_event_close(cpu, pevent);
+
+ if (pevent->id)
+ put_event_id(pevent->id);
kfree(pevent->name);
kfree(pevent);

@@ -306,6 +340,8 @@ void __init perf_register_persistent(void)
{
int cpu;

+ idr_init(&event_idr);
+ mutex_init(&event_lock);
perf_pmu_register(&persistent_pmu, "persistent", PERF_TYPE_PERSISTENT);

for_each_possible_cpu(cpu) {
--
1.8.3.2


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