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Subject[PATCH 3/3] tracing/ftrace: fix a memory leak in stat tracing
From: Frederic Weisbecker <fweisbec@gmail.com>

Impact: fix memory leak

This patch fixes a memory leak inside reset_stat_list(). The freeing
loop iterated only once.

Also turn the stat_list into a simple struct list_head, which
simplify the code and avoid an unused static pointer.

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
kernel/trace/trace_stat.c | 39 +++++++++++++++------------------------
1 files changed, 15 insertions(+), 24 deletions(-)
diff --git a/kernel/trace/trace_stat.c b/kernel/trace/trace_stat.c
index 6f194a3..4cb4ff2 100644
--- a/kernel/trace/trace_stat.c
+++ b/kernel/trace/trace_stat.c
@@ -21,7 +21,7 @@ struct trace_stat_list {
void *stat;
};

-static struct trace_stat_list stat_list;
+static LIST_HEAD(stat_list);

/*
* This is a copy of the current tracer to avoid racy
@@ -39,22 +39,12 @@ static DEFINE_MUTEX(stat_list_mutex);

static void reset_stat_list(void)
{
- struct trace_stat_list *node;
- struct list_head *next;
+ struct trace_stat_list *node, *next;

- if (list_empty(&stat_list.list))
- return;
-
- node = list_entry(stat_list.list.next, struct trace_stat_list, list);
- next = node->list.next;
-
- while (&node->list != next) {
+ list_for_each_entry_safe(node, next, &stat_list, list)
kfree(node);
- node = list_entry(next, struct trace_stat_list, list);
- }
- kfree(node);

- INIT_LIST_HEAD(&stat_list.list);
+ INIT_LIST_HEAD(&stat_list);
}

void init_tracer_stat(struct tracer *trace)
@@ -107,7 +97,7 @@ static int stat_seq_init(void)
}

INIT_LIST_HEAD(&new_entry->list);
- list_add(&new_entry->list, &stat_list.list);
+ list_add(&new_entry->list, &stat_list);
new_entry->stat = current_tracer.stat_start();

prev_stat = new_entry->stat;
@@ -130,7 +120,7 @@ static int stat_seq_init(void)
if (!new_entry->stat)
break;

- list_for_each_entry(iter_entry, &stat_list.list, list) {
+ list_for_each_entry(iter_entry, &stat_list, list) {
/* Insertion with a descendent sorting */
if (current_tracer.stat_cmp(new_entry->stat,
iter_entry->stat) > 0) {
@@ -141,7 +131,7 @@ static int stat_seq_init(void)

/* The current smaller value */
} else if (list_is_last(&iter_entry->list,
- &stat_list.list)) {
+ &stat_list)) {
list_add(&new_entry->list, &iter_entry->list);
break;
}
@@ -162,7 +152,7 @@ exit_free_list:

static void *stat_seq_start(struct seq_file *s, loff_t *pos)
{
- struct trace_stat_list *l = (struct trace_stat_list *)s->private;
+ struct list_head *l = (struct list_head *)s->private;

/* Prevent from tracer switch or stat_list modification */
mutex_lock(&stat_list_mutex);
@@ -171,14 +161,14 @@ static void *stat_seq_start(struct seq_file *s, loff_t *pos)
if (!*pos && current_tracer.stat_headers)
current_tracer.stat_headers(s);

- return seq_list_start(&l->list, *pos);
+ return seq_list_start(l, *pos);
}

static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos)
{
- struct trace_stat_list *l = (struct trace_stat_list *)s->private;
+ struct list_head *l = (struct list_head *)s->private;

- return seq_list_next(p, &l->list, pos);
+ return seq_list_next(p, l, pos);
}

static void stat_seq_stop(struct seq_file *m, void *p)
@@ -188,8 +178,10 @@ static void stat_seq_stop(struct seq_file *m, void *p)

static int stat_seq_show(struct seq_file *s, void *v)
{
- struct trace_stat_list *l = list_entry(v, struct trace_stat_list, list);
- return current_tracer.stat_show(s, l->stat);
+ struct trace_stat_list *entry =
+ list_entry(v, struct trace_stat_list, list);
+
+ return current_tracer.stat_show(s, entry->stat);
}

static const struct seq_operations trace_stat_seq_ops = {
@@ -237,7 +229,6 @@ static int __init tracing_stat_init(void)
struct dentry *d_tracing;
struct dentry *entry;

- INIT_LIST_HEAD(&stat_list.list);
d_tracing = tracing_init_dentry();

entry = debugfs_create_file("trace_stat", 0444, d_tracing,
--
1.5.6.5
--


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