1 files changed, 169 insertions, 61 deletions

diff --git a/kernel/trace/trace_stat.c b/kernel/trace/trace_stat.c
index f110ce9ce7fb..1515f9e7adfc 100644
--- a/kernel/trace/trace_stat.c
+++ b/kernel/trace/trace_stat.c
@@ -21,37 +21,87 @@ struct trace_stat_list {
         void *stat;
 };
 
-static LIST_HEAD(stat_list);
-
-/*
- * This is a copy of the current tracer to avoid racy
- * and dangerous output while the current tracer is
- * switched.
- */
-static struct tracer current_tracer;
+/* 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;
+};
 
-/*
- * Protect both the current tracer and the global
- * stat list.
- */
-static DEFINE_MUTEX(stat_list_mutex);
+/* 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 void reset_stat_list(void)
+static void reset_stat_session(struct tracer_stat_session *session)
 {
         struct trace_stat_list *node, *next;
 
-        list_for_each_entry_safe(node, next, &stat_list, list)
+        list_for_each_entry_safe(node, next, &session->stat_list, list)
                 kfree(node);
 
-        INIT_LIST_HEAD(&stat_list);
+        INIT_LIST_HEAD(&session->stat_list);
 }
 
-void init_tracer_stat(struct tracer *trace)
+/* Called when a tracer is initialized */
+static int init_all_sessions(int nb, struct tracer_stat *ts)
 {
-        mutex_lock(&stat_list_mutex);
-        current_tracer = *trace;
-        mutex_unlock(&stat_list_mutex);
+        int i, j;
+        struct tracer_stat_session *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;
+
+        for (i = 0; i < nb; i++) {
+                session = kmalloc(sizeof(struct tracer_stat_session) * nb,
+                                  GFP_KERNEL);
+                if (!session)
+                        goto free_sessions;
+
+                INIT_LIST_HEAD(&session->stat_list);
+                mutex_init(&session->stat_mutex);
+                session->ts = &ts[i];
+                all_stat_sessions[i] = session;
+        }
+        nb_sessions = nb;
+        return 0;
+
+free_sessions:
+
+        for (j = 0; j < i; j++)
+                kfree(all_stat_sessions[i]);
+
+        kfree(all_stat_sessions);
+        all_stat_sessions = NULL;
+
+        return -ENOMEM;
+}
+
+static int basic_tracer_stat_checks(struct tracer_stat *ts)
+{
+        int i;
+
+        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;
+        }
+        return i;
 }
 
 /*
@@ -69,22 +119,19 @@ static int dummy_cmp(void *p1, void *p2)
  * 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(void)
+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;
         int ret = 0;
         int i;
 
-        mutex_lock(&stat_list_mutex);
-        reset_stat_list();
-
-        if (!current_tracer.stat_start || !current_tracer.stat_next ||
-                                        !current_tracer.stat_show)
-                goto exit;
+        mutex_lock(&session->stat_mutex);
+        reset_stat_session(session);
 
-        if (!current_tracer.stat_cmp)
-                current_tracer.stat_cmp = dummy_cmp;
+        if (!ts->stat_cmp)
+                ts->stat_cmp = dummy_cmp;
 
         /*
          * The first entry. Actually this is the second, but the first
@@ -97,9 +144,10 @@ static int stat_seq_init(void)
         }
 
         INIT_LIST_HEAD(&new_entry->list);
-        list_add(&new_entry->list, &stat_list);
-        new_entry->stat = current_tracer.stat_start();
 
+        list_add(&new_entry->list, &session->stat_list);
+
+        new_entry->stat = ts->stat_start();
         prev_stat = new_entry->stat;
 
         /*
@@ -114,15 +162,16 @@ static int stat_seq_init(void)
                 }
 
                 INIT_LIST_HEAD(&new_entry->list);
-                new_entry->stat = current_tracer.stat_next(prev_stat, i);
+                new_entry->stat = ts->stat_next(prev_stat, i);
 
                 /* End of insertion */
                 if (!new_entry->stat)
                         break;
 
-                list_for_each_entry(iter_entry, &stat_list, list) {
+                list_for_each_entry(iter_entry, &session->stat_list, list) {
+
                         /* Insertion with a descendent sorting */
-                        if (current_tracer.stat_cmp(new_entry->stat,
+                        if (ts->stat_cmp(new_entry->stat,
                                                 iter_entry->stat) > 0) {
 
                                 list_add_tail(&new_entry->list,
@@ -131,7 +180,7 @@ static int stat_seq_init(void)
 
                         /* The current smaller value */
                         } else if (list_is_last(&iter_entry->list,
-                                                &stat_list)) {
+                                                &session->stat_list)) {
                                 list_add(&new_entry->list, &iter_entry->list);
                                 break;
                         }
@@ -140,49 +189,49 @@ static int stat_seq_init(void)
                 prev_stat = new_entry->stat;
         }
 exit:
-        mutex_unlock(&stat_list_mutex);
+        mutex_unlock(&session->stat_mutex);
         return ret;
 
 exit_free_list:
-        reset_stat_list();
-        mutex_unlock(&stat_list_mutex);
+        reset_stat_session(session);
+        mutex_unlock(&session->stat_mutex);
         return ret;
 }
 
 
 static void *stat_seq_start(struct seq_file *s, loff_t *pos)
 {
-        struct list_head *l = (struct list_head *)s->private;
+        struct tracer_stat_session *session = s->private;
 
         /* Prevent from tracer switch or stat_list modification */
-        mutex_lock(&stat_list_mutex);
+        mutex_lock(&session->stat_mutex);
 
         /* If we are in the beginning of the file, print the headers */
-        if (!*pos && current_tracer.stat_headers)
-                current_tracer.stat_headers(s);
+        if (!*pos && session->ts->stat_headers)
+                session->ts->stat_headers(s);
 
-        return seq_list_start(l, *pos);
+        return seq_list_start(&session->stat_list, *pos);
 }
 
 static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos)
 {
-        struct list_head *l = (struct list_head *)s->private;
+        struct tracer_stat_session *session = s->private;
 
-        return seq_list_next(p, l, pos);
+        return seq_list_next(p, &session->stat_list, pos);
 }
 
-static void stat_seq_stop(struct seq_file *m, void *p)
+static void stat_seq_stop(struct seq_file *s, void *p)
 {
-        mutex_unlock(&stat_list_mutex);
+        struct tracer_stat_session *session = s->private;
+        mutex_unlock(&session->stat_mutex);
 }
 
 static int stat_seq_show(struct seq_file *s, void *v)
 {
-        struct trace_stat_list *entry;
-
-        entry = list_entry(v, struct trace_stat_list, list);
+        struct tracer_stat_session *session = s->private;
+        struct trace_stat_list *l = list_entry(v, struct trace_stat_list, list);
 
-        return current_tracer.stat_show(s, entry->stat);
+        return session->ts->stat_show(s, l->stat);
 }
 
 static const struct seq_operations trace_stat_seq_ops = {
@@ -192,15 +241,18 @@ static const struct seq_operations trace_stat_seq_ops = {
         .show = stat_seq_show
 };
 
+/* The session stat is refilled and resorted at each stat file opening */
 static int tracing_stat_open(struct inode *inode, struct file *file)
 {
         int ret;
 
+        struct tracer_stat_session *session = inode->i_private;
+
         ret = seq_open(file, &trace_stat_seq_ops);
         if (!ret) {
                 struct seq_file *m = file->private_data;
-                m->private = &stat_list;
-                ret = stat_seq_init();
+                m->private = session;
+                ret = stat_seq_init(session);
         }
 
         return ret;
@@ -212,9 +264,12 @@ static int tracing_stat_open(struct inode *inode, struct file *file)
  */
 static int tracing_stat_release(struct inode *i, struct file *f)
 {
-        mutex_lock(&stat_list_mutex);
-        reset_stat_list();
-        mutex_unlock(&stat_list_mutex);
+        struct tracer_stat_session *session = i->i_private;
+
+        mutex_lock(&session->stat_mutex);
+        reset_stat_session(session);
+        mutex_unlock(&session->stat_mutex);
+
         return 0;
 }
 
@@ -225,17 +280,70 @@ 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)
 {
         struct dentry *d_tracing;
-        struct dentry *entry;
 
         d_tracing = tracing_init_dentry();
 
-        entry = debugfs_create_file("trace_stat", 0444, d_tracing,
-                                        NULL,
-                                    &tracing_stat_fops);
-        if (!entry)
+        stat_dir = debugfs_create_dir("trace_stat", d_tracing);
+        if (!stat_dir)
                 pr_warning("Could not create debugfs "
                            "'trace_stat' entry\n");
         return 0;