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Subject[PATCH RFC 06/10] perf tools: lock to protect comm_str rb tree
Date
From: Kan Liang <kan.liang@intel.com>

Add comm_str_lock to protect comm_str rb tree.

Signed-off-by: Kan Liang <kan.liang@intel.com>
---
tools/perf/util/comm.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/comm.c b/tools/perf/util/comm.c
index 7bc981b..1bdfef1 100644
--- a/tools/perf/util/comm.c
+++ b/tools/perf/util/comm.c
@@ -5,6 +5,7 @@
#include <stdio.h>
#include <string.h>
#include <linux/refcount.h>
+#include <pthread.h>

struct comm_str {
char *str;
@@ -14,6 +15,7 @@ struct comm_str {

/* Should perhaps be moved to struct machine */
static struct rb_root comm_str_root;
+static pthread_mutex_t comm_str_lock = PTHREAD_MUTEX_INITIALIZER;

static struct comm_str *comm_str__get(struct comm_str *cs)
{
@@ -24,11 +26,13 @@ static struct comm_str *comm_str__get(struct comm_str *cs)

static void comm_str__put(struct comm_str *cs)
{
+ pthread_mutex_lock(&comm_str_lock);
if (cs && refcount_dec_and_test(&cs->refcnt)) {
rb_erase(&cs->rb_node, &comm_str_root);
zfree(&cs->str);
free(cs);
}
+ pthread_mutex_unlock(&comm_str_lock);
}

static struct comm_str *comm_str__alloc(const char *str)
@@ -52,18 +56,22 @@ static struct comm_str *comm_str__alloc(const char *str)

static struct comm_str *comm_str__findnew(const char *str, struct rb_root *root)
{
- struct rb_node **p = &root->rb_node;
struct rb_node *parent = NULL;
struct comm_str *iter, *new;
+ struct rb_node **p;
int cmp;

+ pthread_mutex_lock(&comm_str_lock);
+ p = &root->rb_node;
while (*p != NULL) {
parent = *p;
iter = rb_entry(parent, struct comm_str, rb_node);

cmp = strcmp(str, iter->str);
- if (!cmp)
- return comm_str__get(iter);
+ if (!cmp) {
+ new = comm_str__get(iter);
+ goto unlock;
+ }

if (cmp < 0)
p = &(*p)->rb_left;
@@ -73,11 +81,13 @@ static struct comm_str *comm_str__findnew(const char *str, struct rb_root *root)

new = comm_str__alloc(str);
if (!new)
- return NULL;
+ goto unlock;

rb_link_node(&new->rb_node, parent, p);
rb_insert_color(&new->rb_node, root);

+unlock:
+ pthread_mutex_unlock(&comm_str_lock);
return new;
}

--
2.5.5
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