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SubjectRe: [PATCH] tracing/ftrace: fix a memory leak in stat tracing

Thanks Frederic!

I'll just add an Impact line to this and push it off to Ingo.

The impact line will simply be:

Impact: fix memory leak

-- Steve

On Tue, 6 Jan 2009, Frederic Weisbecker wrote:

> 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>
> ---
> 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,
> --
> 1.6.0.4
>
>
>
>


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