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Subject[PATCH 3/3] tracing/stat: do some cleanups
- remove duplicate code in stat_seq_init()
- update comments to reflect the change from stat list to stat rbtree

[ Impact: clean up ]

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
kernel/trace/trace_stat.c | 56 +++++++++++++++++---------------------------
1 files changed, 22 insertions(+), 34 deletions(-)
diff --git a/kernel/trace/trace_stat.c b/kernel/trace/trace_stat.c
index ed18701..abf2ba1 100644
--- a/kernel/trace/trace_stat.c
+++ b/kernel/trace/trace_stat.c
@@ -8,7 +8,6 @@
*
*/

-
#include <linux/list.h>
#include <linux/rbtree.h>
#include <linux/debugfs.h>
@@ -64,10 +63,15 @@ static void destroy_session(struct stat_session *session)

typedef int (*cmp_stat_t)(void *, void *);

-static void
-insert_stat(struct rb_root *root, struct stat_node *data, cmp_stat_t cmp)
+static int insert_stat(struct rb_root *root, void *stat, cmp_stat_t cmp)
{
struct rb_node **new = &(root->rb_node), *parent = NULL;
+ struct stat_node *data;
+
+ data = kzalloc(sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+ data->stat = stat;

while (*new) {
struct stat_node *this;
@@ -85,12 +89,13 @@ insert_stat(struct rb_root *root, struct stat_node *data, cmp_stat_t cmp)

rb_link_node(&data->node, parent, new);
rb_insert_color(&data->node, root);
+ return 0;
}

/*
* For tracers that don't provide a stat_cmp callback.
- * This one will force an immediate insertion on tail of
- * the list.
+ * This one will force an insertion on rightmost node
+ * of the tree.
*/
static int dummy_cmp(void *p1, void *p2)
{
@@ -98,15 +103,14 @@ static int dummy_cmp(void *p1, void *p2)
}

/*
- * Initialize the stat list at each trace_stat file opening.
+ * Initialize the stat rbtree at each trace_stat file opening.
* All of these copies and sorting are required on all opening
* since the stats could have changed between two file sessions.
*/
static int stat_seq_init(struct stat_session *session)
{
struct tracer_stat *ts = session->ts;
- struct stat_node *new_entry;
- struct rb_root *root;
+ struct rb_root *root = &session->stat_root;
void *stat;
int ret = 0;
int i;
@@ -121,23 +125,13 @@ static int stat_seq_init(struct stat_session *session)
if (!stat)
goto exit;

- /*
- * The first entry. Actually this is the second, but the first
- * one (the stat_list head) is pointless.
- */
- new_entry = kzalloc(sizeof(*new_entry), GFP_KERNEL);
- if (!new_entry) {
- ret = -ENOMEM;
+ ret = insert_stat(root, stat, ts->stat_cmp);
+ if (ret)
goto exit;
- }
- root = &session->stat_root;
- insert_stat(root, new_entry, dummy_cmp);
-
- new_entry->stat = stat;

/*
- * Iterate over the tracer stat entries and store them in a sorted
- * list.
+ * Iterate over the tracer stat entries and store them
+ * in an rbtree.
*/
for (i = 1; ; i++) {
stat = ts->stat_next(stat, i);
@@ -146,22 +140,16 @@ static int stat_seq_init(struct stat_session *session)
if (!stat)
break;

- new_entry = kzalloc(sizeof(*new_entry), GFP_KERNEL);
- if (!new_entry) {
- ret = -ENOMEM;
- goto exit_free_list;
- }
-
- new_entry->stat = stat;
-
- insert_stat(root, new_entry, ts->stat_cmp);
+ ret = insert_stat(root, stat, ts->stat_cmp);
+ if (ret)
+ goto exit_free_rbtree;
}

exit:
mutex_unlock(&session->stat_mutex);
return ret;

-exit_free_list:
+exit_free_rbtree:
reset_stat_session(session);
mutex_unlock(&session->stat_mutex);
return ret;
@@ -174,7 +162,7 @@ static void *stat_seq_start(struct seq_file *s, loff_t *pos)
struct rb_node *node;
int i;

- /* Prevent from tracer switch or stat_list modification */
+ /* Prevent from tracer switch or rbtree modification */
mutex_lock(&session->stat_mutex);

/* If we are in the beginning of the file, print the headers */
@@ -252,7 +240,7 @@ static int tracing_stat_open(struct inode *inode, struct file *file)
}

/*
- * Avoid consuming memory with our now useless list.
+ * Avoid consuming memory with our now useless rbtree.
*/
static int tracing_stat_release(struct inode *i, struct file *f)
{
--
1.5.4.rc3


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