1 files changed, 81 insertions, 110 deletions

diff --git a/kernel/trace/trace_stat.c b/kernel/trace/trace_stat.c
index 1515f9e7adfc..cb29282b9485 100644
--- a/kernel/trace/trace_stat.c
+++ b/kernel/trace/trace_stat.c
@@ -10,28 +10,32 @@
 
 
 #include <linux/list.h>
-#include <linux/seq_file.h>
 #include <linux/debugfs.h>
+#include "trace_stat.h"
 #include "trace.h"
 
 
 /* List of stat entries from a tracer */
 struct trace_stat_list {
-        struct list_head list;
-        void *stat;
+        struct list_head        list;
+        void                    *stat;
 };
 
 /* A stat session is the stats output in one file */
 struct tracer_stat_session {
-        struct tracer_stat *ts;
-        struct list_head stat_list;
-        struct mutex stat_mutex;
+        struct list_head        session_list;
+        struct tracer_stat      *ts;
+        struct list_head        stat_list;
+        struct mutex            stat_mutex;
+        struct dentry           *file;
 };
 
 /* All of the sessions currently in use. Each stat file embeed one session */
-static struct tracer_stat_session **all_stat_sessions;
-static int nb_sessions;
-static struct dentry *stat_dir, **stat_files;
+static LIST_HEAD(all_stat_sessions);
+static DEFINE_MUTEX(all_stat_sessions_mutex);
+
+/* The root directory for all stat files */
+static struct dentry *stat_dir;
 
 
 static void reset_stat_session(struct tracer_stat_session *session)
@@ -44,66 +48,77 @@ static void reset_stat_session(struct tracer_stat_session *session)
         INIT_LIST_HEAD(&session->stat_list);
 }
 
-/* Called when a tracer is initialized */
-static int init_all_sessions(int nb, struct tracer_stat *ts)
+static void destroy_session(struct tracer_stat_session *session)
 {
-        int i, j;
-        struct tracer_stat_session *session;
+        debugfs_remove(session->file);
+        reset_stat_session(session);
+        mutex_destroy(&session->stat_mutex);
+        kfree(session);
+}
 
-        nb_sessions = 0;
 
-        if (all_stat_sessions) {
-                for (i = 0; i < nb_sessions; i++) {
-                        session = all_stat_sessions[i];
-                        reset_stat_session(session);
-                        mutex_destroy(&session->stat_mutex);
-                        kfree(session);
-                }
-        }
-        all_stat_sessions = kmalloc(sizeof(struct tracer_stat_session *) * nb,
-                                    GFP_KERNEL);
-        if (!all_stat_sessions)
-                return -ENOMEM;
+static int init_stat_file(struct tracer_stat_session *session);
 
-        for (i = 0; i < nb; i++) {
-                session = kmalloc(sizeof(struct tracer_stat_session) * nb,
-                                  GFP_KERNEL);
-                if (!session)
-                        goto free_sessions;
+int register_stat_tracer(struct tracer_stat *trace)
+{
+        struct tracer_stat_session *session, *node, *tmp;
+        int ret;
+
+        if (!trace)
+                return -EINVAL;
+
+        if (!trace->stat_start || !trace->stat_next || !trace->stat_show)
+                return -EINVAL;
 
-                INIT_LIST_HEAD(&session->stat_list);
-                mutex_init(&session->stat_mutex);
-                session->ts = &ts[i];
-                all_stat_sessions[i] = session;
+        /* Already registered? */
+        mutex_lock(&all_stat_sessions_mutex);
+        list_for_each_entry_safe(node, tmp, &all_stat_sessions, session_list) {
+                if (node->ts == trace)
+                        return -EINVAL;
         }
-        nb_sessions = nb;
-        return 0;
+        mutex_unlock(&all_stat_sessions_mutex);
+
+        /* Init the session */
+        session = kmalloc(sizeof(struct tracer_stat_session), GFP_KERNEL);
+        if (!session)
+                return -ENOMEM;
 
-free_sessions:
+        session->ts = trace;
+        INIT_LIST_HEAD(&session->session_list);
+        INIT_LIST_HEAD(&session->stat_list);
+        mutex_init(&session->stat_mutex);
+        session->file = NULL;
 
-        for (j = 0; j < i; j++)
-                kfree(all_stat_sessions[i]);
+        ret = init_stat_file(session);
+        if (ret) {
+                destroy_session(session);
+                return ret;
+        }
 
-        kfree(all_stat_sessions);
-        all_stat_sessions = NULL;
+        /* Register */
+        mutex_lock(&all_stat_sessions_mutex);
+        list_add_tail(&session->session_list, &all_stat_sessions);
+        mutex_unlock(&all_stat_sessions_mutex);
 
-        return -ENOMEM;
+        return 0;
 }
 
-static int basic_tracer_stat_checks(struct tracer_stat *ts)
+void unregister_stat_tracer(struct tracer_stat *trace)
 {
-        int i;
+        struct tracer_stat_session *node, *tmp;
 
-        if (!ts)
-                return 0;
-
-        for (i = 0; ts[i].name; i++) {
-                if (!ts[i].stat_start || !ts[i].stat_next || !ts[i].stat_show)
-                        return -EBUSY;
+        mutex_lock(&all_stat_sessions_mutex);
+        list_for_each_entry_safe(node, tmp, &all_stat_sessions, session_list) {
+                if (node->ts == trace) {
+                        list_del(&node->session_list);
+                        destroy_session(node);
+                        break;
+                }
         }
-        return i;
+        mutex_unlock(&all_stat_sessions_mutex);
 }
 
+
 /*
  * For tracers that don't provide a stat_cmp callback.
  * This one will force an immediate insertion on tail of
@@ -280,63 +295,7 @@ static const struct file_operations tracing_stat_fops = {
         .release        = tracing_stat_release
 };
 
-
-static void destroy_trace_stat_files(void)
-{
-        int i;
-
-        if (stat_files) {
-                for (i = 0; i < nb_sessions; i++)
-                        debugfs_remove(stat_files[i]);
-                kfree(stat_files);
-                stat_files = NULL;
-        }
-}
-
-static void init_trace_stat_files(void)
-{
-        int i;
-
-        if (!stat_dir || !nb_sessions)
-                return;
-
-        stat_files = kmalloc(sizeof(struct dentry *) * nb_sessions, GFP_KERNEL);
-
-        if (!stat_files) {
-                pr_warning("trace stat: not enough memory\n");
-                return;
-        }
-
-        for (i = 0; i < nb_sessions; i++) {
-                struct tracer_stat_session *session = all_stat_sessions[i];
-                stat_files[i] = debugfs_create_file(session->ts->name, 0644,
-                                                stat_dir,
-                                                session, &tracing_stat_fops);
-                if (!stat_files[i])
-                        pr_warning("cannot create %s entry\n",
-                                   session->ts->name);
-        }
-}
-
-void init_tracer_stat(struct tracer *trace)
-{
-        int nb = basic_tracer_stat_checks(trace->stats);
-
-        destroy_trace_stat_files();
-
-        if (nb < 0) {
-                pr_warning("stat tracing: missing stat callback on %s\n",
-                           trace->name);
-                return;
-        }
-        if (!nb)
-                return;
-
-        init_all_sessions(nb, trace->stats);
-        init_trace_stat_files();
-}
-
-static int __init tracing_stat_init(void)
+static int tracing_stat_init(void)
 {
         struct dentry *d_tracing;
 
@@ -348,4 +307,16 @@ static int __init tracing_stat_init(void)
                            "'trace_stat' entry\n");
         return 0;
 }
-fs_initcall(tracing_stat_init);
+
+static int init_stat_file(struct tracer_stat_session *session)
+{
+        if (!stat_dir && tracing_stat_init())
+                return -ENODEV;
+
+        session->file = debugfs_create_file(session->ts->name, 0644,
+                                            stat_dir,
+                                            session, &tracing_stat_fops);
+        if (!session->file)
+                return -ENOMEM;
+        return 0;
+}