tracing/ftrace: fix a memory leak in stat tracing

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>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/trace/trace_stat.c b/kernel/trace/trace_stat.c
index 6f194a33a64a4d2c2d1a748478e49b2a467a5e28..4cb4ff27646d70b1f014d1d6561c4f0f1aeb3d2b 100644 (file)
--- 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,