tracing/events: simplify system_enable_read()

[safe/jmp/linux-2.6] / kernel / trace / trace_stat.c

diff --git a/kernel/trace/trace_stat.c b/kernel/trace/trace_stat.c
index eae9cef..fdde3a4 100644 (file)
--- a/kernel/trace/trace_stat.c
+++ b/kernel/trace/trace_stat.c
@@ -30,7 +30,7 @@ struct tracer_stat_session {
        struct dentry           *file;
 };
 
-/* All of the sessions currently in use. Each stat file embeed one session */
+/* All of the sessions currently in use. Each stat file embed one session */
 static LIST_HEAD(all_stat_sessions);
 static DEFINE_MUTEX(all_stat_sessions_mutex);
 
@@ -75,7 +75,7 @@ static int stat_seq_init(struct tracer_stat_session *session)
 {
        struct trace_stat_list *iter_entry, *new_entry;
        struct tracer_stat *ts = session->ts;
-       void *prev_stat;
+       void *stat;
        int ret = 0;
        int i;
 
@@ -85,6 +85,10 @@ static int stat_seq_init(struct tracer_stat_session *session)
        if (!ts->stat_cmp)
                ts->stat_cmp = dummy_cmp;
 
+       stat = ts->stat_start(ts);
+       if (!stat)
+               goto exit;
+
        /*
         * The first entry. Actually this is the second, but the first
         * one (the stat_list head) is pointless.
@@ -99,14 +103,19 @@ static int stat_seq_init(struct tracer_stat_session *session)
 
        list_add(&new_entry->list, &session->stat_list);
 
-       new_entry->stat = ts->stat_start();
-       prev_stat = new_entry->stat;
+       new_entry->stat = stat;
 
        /*
         * Iterate over the tracer stat entries and store them in a sorted
         * list.
         */
        for (i = 1; ; i++) {
+               stat = ts->stat_next(stat, i);
+
+               /* End of insertion */
+               if (!stat)
+                       break;
+
                new_entry = kmalloc(sizeof(struct trace_stat_list), GFP_KERNEL);
                if (!new_entry) {
                        ret = -ENOMEM;
@@ -114,31 +123,23 @@ static int stat_seq_init(struct tracer_stat_session *session)
                }
 
                INIT_LIST_HEAD(&new_entry->list);
-               new_entry->stat = ts->stat_next(prev_stat, i);
+               new_entry->stat = stat;
 
-               /* End of insertion */
-               if (!new_entry->stat)
-                       break;
-
-               list_for_each_entry(iter_entry, &session->stat_list, list) {
+               list_for_each_entry_reverse(iter_entry, &session->stat_list,
+                               list) {
 
                        /* Insertion with a descendent sorting */
-                       if (ts->stat_cmp(new_entry->stat,
-                                               iter_entry->stat) > 0) {
-
-                               list_add_tail(&new_entry->list,
-                                               &iter_entry->list);
-                               break;
+                       if (ts->stat_cmp(iter_entry->stat,
+                                       new_entry->stat) >= 0) {
 
-                       /* The current smaller value */
-                       } else if (list_is_last(&iter_entry->list,
-                                               &session->stat_list)) {
                                list_add(&new_entry->list, &iter_entry->list);
                                break;
                        }
                }
 
-               prev_stat = new_entry->stat;
+               /* The current larger value */
+               if (list_empty(&new_entry->list))
+                       list_add(&new_entry->list, &session->stat_list);
        }
 exit:
        mutex_unlock(&session->stat_mutex);
@@ -160,7 +161,7 @@ static void *stat_seq_start(struct seq_file *s, loff_t *pos)
 
        /* If we are in the beginning of the file, print the headers */
        if (!*pos && session->ts->stat_headers)
-               session->ts->stat_headers(s);
+               return SEQ_START_TOKEN;
 
        return seq_list_start(&session->stat_list, *pos);
 }
@@ -169,6 +170,9 @@ static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos)
 {
        struct tracer_stat_session *session = s->private;
 
+       if (p == SEQ_START_TOKEN)
+               return seq_list_start(&session->stat_list, *pos);
+
        return seq_list_next(p, &session->stat_list, pos);
 }
 
@@ -183,6 +187,9 @@ static int stat_seq_show(struct seq_file *s, void *v)
        struct tracer_stat_session *session = s->private;
        struct trace_stat_list *l = list_entry(v, struct trace_stat_list, list);
 
+       if (v == SEQ_START_TOKEN)
+               return session->ts->stat_headers(s);
+
        return session->ts->stat_show(s, l->stat);
 }