tracing: Separate out trace events from global variables

The trace events for ftrace are all defined via global variables.
The arrays of events and event systems are linked to a global list.
This prevents multiple users of the event system (what to enable and
what not to).

By adding descriptors to represent the event/file relation, as well
as to which trace_array descriptor they are associated with, allows
for more than one set of events to be defined. Once the trace events
files have a link between the trace event and the trace_array they
are associated with, we can create multiple trace_arrays that can
record separate events in separate buffers.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 533 insertions, 243 deletions

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 57e9b284250c..439955239bae 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -36,6 +36,19 @@ EXPORT_SYMBOL_GPL(event_storage);
 LIST_HEAD(ftrace_events);
 LIST_HEAD(ftrace_common_fields);
 
+/* Double loops, do not use break, only goto's work */
+#define do_for_each_event_file(tr, file)                        \
+        list_for_each_entry(tr, &ftrace_trace_arrays, list) {   \
+                list_for_each_entry(file, &tr->events, list)
+
+#define do_for_each_event_file_safe(tr, file)                   \
+        list_for_each_entry(tr, &ftrace_trace_arrays, list) {   \
+                struct ftrace_event_file *___n;                         \
+                list_for_each_entry_safe(file, ___n, &tr->events, list)
+
+#define while_for_each_event_file()             \
+        }
+
 struct list_head *
 trace_get_fields(struct ftrace_event_call *event_call)
 {
@@ -149,15 +162,17 @@ EXPORT_SYMBOL_GPL(trace_event_raw_init);
 int ftrace_event_reg(struct ftrace_event_call *call,
                      enum trace_reg type, void *data)
 {
+        struct ftrace_event_file *file = data;
+
         switch (type) {
         case TRACE_REG_REGISTER:
                 return tracepoint_probe_register(call->name,
                                                  call->class->probe,
-                                                 call);
+                                                 file);
         case TRACE_REG_UNREGISTER:
                 tracepoint_probe_unregister(call->name,
                                             call->class->probe,
-                                            call);
+                                            file);
                 return 0;
 
 #ifdef CONFIG_PERF_EVENTS
@@ -183,54 +198,57 @@ EXPORT_SYMBOL_GPL(ftrace_event_reg);
 
 void trace_event_enable_cmd_record(bool enable)
 {
-        struct ftrace_event_call *call;
+        struct ftrace_event_file *file;
+        struct trace_array *tr;
 
         mutex_lock(&event_mutex);
-        list_for_each_entry(call, &ftrace_events, list) {
-                if (!(call->flags & TRACE_EVENT_FL_ENABLED))
+        do_for_each_event_file(tr, file) {
+
+                if (!(file->flags & FTRACE_EVENT_FL_ENABLED))
                         continue;
 
                 if (enable) {
                         tracing_start_cmdline_record();
-                        call->flags |= TRACE_EVENT_FL_RECORDED_CMD;
+                        file->flags |= FTRACE_EVENT_FL_RECORDED_CMD;
                 } else {
                         tracing_stop_cmdline_record();
-                        call->flags &= ~TRACE_EVENT_FL_RECORDED_CMD;
+                        file->flags &= ~FTRACE_EVENT_FL_RECORDED_CMD;
                 }
-        }
+        } while_for_each_event_file();
         mutex_unlock(&event_mutex);
 }
 
-static int ftrace_event_enable_disable(struct ftrace_event_call *call,
-                                        int enable)
+static int ftrace_event_enable_disable(struct ftrace_event_file *file,
+                                       int enable)
 {
+        struct ftrace_event_call *call = file->event_call;
         int ret = 0;
 
         switch (enable) {
         case 0:
-                if (call->flags & TRACE_EVENT_FL_ENABLED) {
-                        call->flags &= ~TRACE_EVENT_FL_ENABLED;
-                        if (call->flags & TRACE_EVENT_FL_RECORDED_CMD) {
+                if (file->flags & FTRACE_EVENT_FL_ENABLED) {
+                        file->flags &= ~FTRACE_EVENT_FL_ENABLED;
+                        if (file->flags & FTRACE_EVENT_FL_RECORDED_CMD) {
                                 tracing_stop_cmdline_record();
-                                call->flags &= ~TRACE_EVENT_FL_RECORDED_CMD;
+                                file->flags &= ~FTRACE_EVENT_FL_RECORDED_CMD;
                         }
-                        call->class->reg(call, TRACE_REG_UNREGISTER, NULL);
+                        call->class->reg(call, TRACE_REG_UNREGISTER, file);
                 }
                 break;
         case 1:
-                if (!(call->flags & TRACE_EVENT_FL_ENABLED)) {
+                if (!(file->flags & FTRACE_EVENT_FL_ENABLED)) {
                         if (trace_flags & TRACE_ITER_RECORD_CMD) {
                                 tracing_start_cmdline_record();
-                                call->flags |= TRACE_EVENT_FL_RECORDED_CMD;
+                                file->flags |= FTRACE_EVENT_FL_RECORDED_CMD;
                         }
-                        ret = call->class->reg(call, TRACE_REG_REGISTER, NULL);
+                        ret = call->class->reg(call, TRACE_REG_REGISTER, file);
                         if (ret) {
                                 tracing_stop_cmdline_record();
                                 pr_info("event trace: Could not enable event "
                                         "%s\n", call->name);
                                 break;
                         }
-                        call->flags |= TRACE_EVENT_FL_ENABLED;
+                        file->flags |= FTRACE_EVENT_FL_ENABLED;
                 }
                 break;
         }
@@ -238,13 +256,13 @@ static int ftrace_event_enable_disable(struct ftrace_event_call *call,
         return ret;
 }
 
-static void ftrace_clear_events(void)
+static void ftrace_clear_events(struct trace_array *tr)
 {
-        struct ftrace_event_call *call;
+        struct ftrace_event_file *file;
 
         mutex_lock(&event_mutex);
-        list_for_each_entry(call, &ftrace_events, list) {
-                ftrace_event_enable_disable(call, 0);
+        list_for_each_entry(file, &tr->events, list) {
+                ftrace_event_enable_disable(file, 0);
         }
         mutex_unlock(&event_mutex);
 }
@@ -257,6 +275,8 @@ static void __put_system(struct event_subsystem *system)
         if (--system->ref_count)
                 return;
 
+        list_del(&system->list);
+
         if (filter) {
                 kfree(filter->filter_string);
                 kfree(filter);
@@ -271,24 +291,45 @@ static void __get_system(struct event_subsystem *system)
         system->ref_count++;
 }
 
-static void put_system(struct event_subsystem *system)
+static void __get_system_dir(struct ftrace_subsystem_dir *dir)
+{
+        WARN_ON_ONCE(dir->ref_count == 0);
+        dir->ref_count++;
+        __get_system(dir->subsystem);
+}
+
+static void __put_system_dir(struct ftrace_subsystem_dir *dir)
+{
+        WARN_ON_ONCE(dir->ref_count == 0);
+        /* If the subsystem is about to be freed, the dir must be too */
+        WARN_ON_ONCE(dir->subsystem->ref_count == 1 && dir->ref_count != 1);
+
+        __put_system(dir->subsystem);
+        if (!--dir->ref_count)
+                kfree(dir);
+}
+
+static void put_system(struct ftrace_subsystem_dir *dir)
 {
         mutex_lock(&event_mutex);
-        __put_system(system);
+        __put_system_dir(dir);
         mutex_unlock(&event_mutex);
 }
 
 /*
  * __ftrace_set_clr_event(NULL, NULL, NULL, set) will set/unset all events.
  */
-static int __ftrace_set_clr_event(const char *match, const char *sub,
-                                  const char *event, int set)
+static int __ftrace_set_clr_event(struct trace_array *tr, const char *match,
+                                  const char *sub, const char *event, int set)
 {
+        struct ftrace_event_file *file;
         struct ftrace_event_call *call;
         int ret = -EINVAL;
 
         mutex_lock(&event_mutex);
-        list_for_each_entry(call, &ftrace_events, list) {
+        list_for_each_entry(file, &tr->events, list) {
+
+                call = file->event_call;
 
                 if (!call->name || !call->class || !call->class->reg)
                         continue;
@@ -307,7 +348,7 @@ static int __ftrace_set_clr_event(const char *match, const char *sub,
                 if (event && strcmp(event, call->name) != 0)
                         continue;
 
-                ftrace_event_enable_disable(call, set);
+                ftrace_event_enable_disable(file, set);
 
                 ret = 0;
         }
@@ -316,7 +357,7 @@ static int __ftrace_set_clr_event(const char *match, const char *sub,
         return ret;
 }
 
-static int ftrace_set_clr_event(char *buf, int set)
+static int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set)
 {
         char *event = NULL, *sub = NULL, *match;
 
@@ -344,7 +385,7 @@ static int ftrace_set_clr_event(char *buf, int set)
                         event = NULL;
         }
 
-        return __ftrace_set_clr_event(match, sub, event, set);
+        return __ftrace_set_clr_event(tr, match, sub, event, set);
 }
 
 /**
@@ -361,7 +402,9 @@ static int ftrace_set_clr_event(char *buf, int set)
  */
 int trace_set_clr_event(const char *system, const char *event, int set)
 {
-        return __ftrace_set_clr_event(NULL, system, event, set);
+        struct trace_array *tr = top_trace_array();
+
+        return __ftrace_set_clr_event(tr, NULL, system, event, set);
 }
 EXPORT_SYMBOL_GPL(trace_set_clr_event);
 
@@ -373,6 +416,8 @@ ftrace_event_write(struct file *file, const char __user *ubuf,
                    size_t cnt, loff_t *ppos)
 {
         struct trace_parser parser;
+        struct seq_file *m = file->private_data;
+        struct trace_array *tr = m->private;
         ssize_t read, ret;
 
         if (!cnt)
@@ -395,7 +440,7 @@ ftrace_event_write(struct file *file, const char __user *ubuf,
 
                 parser.buffer[parser.idx] = 0;
 
-                ret = ftrace_set_clr_event(parser.buffer + !set, set);
+                ret = ftrace_set_clr_event(tr, parser.buffer + !set, set);
                 if (ret)
                         goto out_put;
         }
@@ -411,17 +456,20 @@ ftrace_event_write(struct file *file, const char __user *ubuf,
 static void *
 t_next(struct seq_file *m, void *v, loff_t *pos)
 {
-        struct ftrace_event_call *call = v;
+        struct ftrace_event_file *file = v;
+        struct ftrace_event_call *call;
+        struct trace_array *tr = m->private;
 
         (*pos)++;
 
-        list_for_each_entry_continue(call, &ftrace_events, list) {
+        list_for_each_entry_continue(file, &tr->events, list) {
+                call = file->event_call;
                 /*
                  * The ftrace subsystem is for showing formats only.
                  * They can not be enabled or disabled via the event files.
                  */
                 if (call->class && call->class->reg)
-                        return call;
+                        return file;
         }
 
         return NULL;
@@ -429,30 +477,32 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
 
 static void *t_start(struct seq_file *m, loff_t *pos)
 {
-        struct ftrace_event_call *call;
+        struct ftrace_event_file *file;
+        struct trace_array *tr = m->private;
         loff_t l;
 
         mutex_lock(&event_mutex);
 
-        call = list_entry(&ftrace_events, struct ftrace_event_call, list);
+        file = list_entry(&tr->events, struct ftrace_event_file, list);
         for (l = 0; l <= *pos; ) {
-                call = t_next(m, call, &l);
-                if (!call)
+                file = t_next(m, file, &l);
+                if (!file)
                         break;
         }
-        return call;
+        return file;
 }
 
 static void *
 s_next(struct seq_file *m, void *v, loff_t *pos)
 {
-        struct ftrace_event_call *call = v;
+        struct ftrace_event_file *file = v;
+        struct trace_array *tr = m->private;
 
         (*pos)++;
 
-        list_for_each_entry_continue(call, &ftrace_events, list) {
-                if (call->flags & TRACE_EVENT_FL_ENABLED)
-                        return call;
+        list_for_each_entry_continue(file, &tr->events, list) {
+                if (file->flags & FTRACE_EVENT_FL_ENABLED)
+                        return file;
         }
 
         return NULL;
@@ -460,23 +510,25 @@ s_next(struct seq_file *m, void *v, loff_t *pos)
 
 static void *s_start(struct seq_file *m, loff_t *pos)
 {
-        struct ftrace_event_call *call;
+        struct ftrace_event_file *file;
+        struct trace_array *tr = m->private;
         loff_t l;
 
         mutex_lock(&event_mutex);
 
-        call = list_entry(&ftrace_events, struct ftrace_event_call, list);
+        file = list_entry(&tr->events, struct ftrace_event_file, list);
         for (l = 0; l <= *pos; ) {
-                call = s_next(m, call, &l);
-                if (!call)
+                file = s_next(m, file, &l);
+                if (!file)
                         break;
         }
-        return call;
+        return file;
 }
 
 static int t_show(struct seq_file *m, void *v)
 {
-        struct ftrace_event_call *call = v;
+        struct ftrace_event_file *file = v;
+        struct ftrace_event_call *call = file->event_call;
 
         if (strcmp(call->class->system, TRACE_SYSTEM) != 0)
                 seq_printf(m, "%s:", call->class->system);
@@ -494,10 +546,10 @@ static ssize_t
 event_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
                   loff_t *ppos)
 {
-        struct ftrace_event_call *call = filp->private_data;
+        struct ftrace_event_file *file = filp->private_data;
         char *buf;
 
-        if (call->flags & TRACE_EVENT_FL_ENABLED)
+        if (file->flags & FTRACE_EVENT_FL_ENABLED)
                 buf = "1\n";
         else
                 buf = "0\n";
@@ -509,10 +561,13 @@ static ssize_t
 event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
                    loff_t *ppos)
 {
-        struct ftrace_event_call *call = filp->private_data;
+        struct ftrace_event_file *file = filp->private_data;
         unsigned long val;
         int ret;
 
+        if (!file)
+                return -EINVAL;
+
         ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
         if (ret)
                 return ret;
@@ -525,7 +580,7 @@ event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
         case 0:
         case 1:
                 mutex_lock(&event_mutex);
-                ret = ftrace_event_enable_disable(call, val);
+                ret = ftrace_event_enable_disable(file, val);
                 mutex_unlock(&event_mutex);
                 break;
 
@@ -543,14 +598,18 @@ system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
                    loff_t *ppos)
 {
         const char set_to_char[4] = { '?', '0', '1', 'X' };
-        struct event_subsystem *system = filp->private_data;
+        struct ftrace_subsystem_dir *dir = filp->private_data;
+        struct event_subsystem *system = dir->subsystem;
         struct ftrace_event_call *call;
+        struct ftrace_event_file *file;
+        struct trace_array *tr = dir->tr;
         char buf[2];
         int set = 0;
         int ret;
 
         mutex_lock(&event_mutex);
-        list_for_each_entry(call, &ftrace_events, list) {
+        list_for_each_entry(file, &tr->events, list) {
+                call = file->event_call;
                 if (!call->name || !call->class || !call->class->reg)
                         continue;
 
@@ -562,7 +621,7 @@ system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
                  * or if all events or cleared, or if we have
                  * a mixture.
                  */
-                set |= (1 << !!(call->flags & TRACE_EVENT_FL_ENABLED));
+                set |= (1 << !!(file->flags & FTRACE_EVENT_FL_ENABLED));
 
                 /*
                  * If we have a mixture, no need to look further.
@@ -584,7 +643,8 @@ static ssize_t
 system_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
                     loff_t *ppos)
 {
-        struct event_subsystem *system = filp->private_data;
+        struct ftrace_subsystem_dir *dir = filp->private_data;
+        struct event_subsystem *system = dir->subsystem;
         const char *name = NULL;
         unsigned long val;
         ssize_t ret;
@@ -607,7 +667,7 @@ system_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
         if (system)
                 name = system->name;
 
-        ret = __ftrace_set_clr_event(NULL, name, NULL, val);
+        ret = __ftrace_set_clr_event(dir->tr, NULL, name, NULL, val);
         if (ret)
                 goto out;
 
@@ -845,43 +905,75 @@ static LIST_HEAD(event_subsystems);
 static int subsystem_open(struct inode *inode, struct file *filp)
 {
         struct event_subsystem *system = NULL;
+        struct ftrace_subsystem_dir *dir = NULL; /* Initialize for gcc */
+        struct trace_array *tr;
         int ret;
 
-        if (!inode->i_private)
-                goto skip_search;
-
         /* Make sure the system still exists */
         mutex_lock(&event_mutex);
-        list_for_each_entry(system, &event_subsystems, list) {
-                if (system == inode->i_private) {
-                        /* Don't open systems with no events */
-                        if (!system->nr_events) {
-                                system = NULL;
-                                break;
+        list_for_each_entry(tr, &ftrace_trace_arrays, list) {
+                list_for_each_entry(dir, &tr->systems, list) {
+                        if (dir == inode->i_private) {
+                                /* Don't open systems with no events */
+                                if (dir->nr_events) {
+                                        __get_system_dir(dir);
+                                        system = dir->subsystem;
+                                }
+                                goto exit_loop;
                         }
-                        __get_system(system);
-                        break;
                 }
         }
+ exit_loop:
         mutex_unlock(&event_mutex);
 
-        if (system != inode->i_private)
+        if (!system)
                 return -ENODEV;
 
- skip_search:
+        /* Some versions of gcc think dir can be uninitialized here */
+        WARN_ON(!dir);
+
         ret = tracing_open_generic(inode, filp);
-        if (ret < 0 && system)
-                put_system(system);
+        if (ret < 0)
+                put_system(dir);
+
+        return ret;
+}
+
+static int system_tr_open(struct inode *inode, struct file *filp)
+{
+        struct ftrace_subsystem_dir *dir;
+        struct trace_array *tr = inode->i_private;
+        int ret;
+
+        /* Make a temporary dir that has no system but points to tr */
+        dir = kzalloc(sizeof(*dir), GFP_KERNEL);
+        if (!dir)
+                return -ENOMEM;
+
+        dir->tr = tr;
+
+        ret = tracing_open_generic(inode, filp);
+        if (ret < 0)
+                kfree(dir);
+
+        filp->private_data = dir;
 
         return ret;
 }
 
 static int subsystem_release(struct inode *inode, struct file *file)
 {
-        struct event_subsystem *system = inode->i_private;
+        struct ftrace_subsystem_dir *dir = file->private_data;
 
-        if (system)
-                put_system(system);
+        /*
+         * If dir->subsystem is NULL, then this is a temporary
+         * descriptor that was made for a trace_array to enable
+         * all subsystems.
+         */
+        if (dir->subsystem)
+                put_system(dir);
+        else
+                kfree(dir);
 
         return 0;
 }
@@ -890,7 +982,8 @@ static ssize_t
 subsystem_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
                       loff_t *ppos)
 {
-        struct event_subsystem *system = filp->private_data;
+        struct ftrace_subsystem_dir *dir = filp->private_data;
+        struct event_subsystem *system = dir->subsystem;
         struct trace_seq *s;
         int r;
 
@@ -915,7 +1008,7 @@ static ssize_t
 subsystem_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
                        loff_t *ppos)
 {
-        struct event_subsystem *system = filp->private_data;
+        struct ftrace_subsystem_dir *dir = filp->private_data;
         char *buf;
         int err;
 
@@ -932,7 +1025,7 @@ subsystem_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
         }
         buf[cnt] = '\0';
 
-        err = apply_subsystem_event_filter(system, buf);
+        err = apply_subsystem_event_filter(dir, buf);
         free_page((unsigned long) buf);
         if (err < 0)
                 return err;
@@ -1041,30 +1134,35 @@ static const struct file_operations ftrace_system_enable_fops = {
         .release = subsystem_release,
 };
 
+static const struct file_operations ftrace_tr_enable_fops = {
+        .open = system_tr_open,
+        .read = system_enable_read,
+        .write = system_enable_write,
+        .llseek = default_llseek,
+        .release = subsystem_release,
+};
+
 static const struct file_operations ftrace_show_header_fops = {
         .open = tracing_open_generic,
         .read = show_header,
         .llseek = default_llseek,
 };
 
-static struct dentry *event_trace_events_dir(void)
+static int
+ftrace_event_open(struct inode *inode, struct file *file,
+                  const struct seq_operations *seq_ops)
 {
-        static struct dentry *d_tracer;
-        static struct dentry *d_events;
-
-        if (d_events)
-                return d_events;
-
-        d_tracer = tracing_init_dentry();
-        if (!d_tracer)
-                return NULL;
+        struct seq_file *m;
+        int ret;
 
-        d_events = debugfs_create_dir("events", d_tracer);
-        if (!d_events)
-                pr_warning("Could not create debugfs "
-                           "'events' directory\n");
+        ret = seq_open(file, seq_ops);
+        if (ret < 0)
+                return ret;
+        m = file->private_data;
+        /* copy tr over to seq ops */
+        m->private = inode->i_private;
 
-        return d_events;
+        return ret;
 }
 
 static int
@@ -1072,117 +1170,169 @@ ftrace_event_avail_open(struct inode *inode, struct file *file)
 {
         const struct seq_operations *seq_ops = &show_event_seq_ops;
 
-        return seq_open(file, seq_ops);
+        return ftrace_event_open(inode, file, seq_ops);
 }
 
 static int
 ftrace_event_set_open(struct inode *inode, struct file *file)
 {
         const struct seq_operations *seq_ops = &show_set_event_seq_ops;
+        struct trace_array *tr = inode->i_private;
 
         if ((file->f_mode & FMODE_WRITE) &&
             (file->f_flags & O_TRUNC))
-                ftrace_clear_events();
+                ftrace_clear_events(tr);
 
-        return seq_open(file, seq_ops);
+        return ftrace_event_open(inode, file, seq_ops);
+}
+
+static struct event_subsystem *
+create_new_subsystem(const char *name)
+{
+        struct event_subsystem *system;
+
+        /* need to create new entry */
+        system = kmalloc(sizeof(*system), GFP_KERNEL);
+        if (!system)
+                return NULL;
+
+        system->ref_count = 1;
+        system->name = kstrdup(name, GFP_KERNEL);
+
+        if (!system->name)
+                goto out_free;
+
+        system->filter = NULL;
+
+        system->filter = kzalloc(sizeof(struct event_filter), GFP_KERNEL);
+        if (!system->filter)
+                goto out_free;
+
+        list_add(&system->list, &event_subsystems);
+
+        return system;
+
+ out_free:
+        kfree(system->name);
+        kfree(system);
+        return NULL;
 }
 
 static struct dentry *
-event_subsystem_dir(const char *name, struct dentry *d_events)
+event_subsystem_dir(struct trace_array *tr, const char *name,
+                    struct ftrace_event_file *file, struct dentry *parent)
 {
+        struct ftrace_subsystem_dir *dir;
         struct event_subsystem *system;
         struct dentry *entry;
 
         /* First see if we did not already create this dir */
-        list_for_each_entry(system, &event_subsystems, list) {
+        list_for_each_entry(dir, &tr->systems, list) {
+                system = dir->subsystem;
                 if (strcmp(system->name, name) == 0) {
-                        system->nr_events++;
-                        return system->entry;
+                        dir->nr_events++;
+                        file->system = dir;
+                        return dir->entry;
                 }
         }
 
-        /* need to create new entry */
-        system = kmalloc(sizeof(*system), GFP_KERNEL);
-        if (!system) {
-                pr_warning("No memory to create event subsystem %s\n",
-                           name);
-                return d_events;
+        /* Now see if the system itself exists. */
+        list_for_each_entry(system, &event_subsystems, list) {
+                if (strcmp(system->name, name) == 0)
+                        break;
         }
+        /* Reset system variable when not found */
+        if (&system->list == &event_subsystems)
+                system = NULL;
 
-        system->entry = debugfs_create_dir(name, d_events);
-        if (!system->entry) {
-                pr_warning("Could not create event subsystem %s\n",
-                           name);
-                kfree(system);
-                return d_events;
-        }
+        dir = kmalloc(sizeof(*dir), GFP_KERNEL);
+        if (!dir)
+                goto out_fail;
 
-        system->nr_events = 1;
-        system->ref_count = 1;
-        system->name = kstrdup(name, GFP_KERNEL);
-        if (!system->name) {
-                debugfs_remove(system->entry);
-                kfree(system);
-                return d_events;
+        if (!system) {
+                system = create_new_subsystem(name);
+                if (!system)
+                        goto out_free;
+        } else
+                __get_system(system);
+
+        dir->entry = debugfs_create_dir(name, parent);
+        if (!dir->entry) {
+                pr_warning("Failed to create system directory %s\n", name);
+                __put_system(system);
+                goto out_free;
         }
 
-        list_add(&system->list, &event_subsystems);
-
-        system->filter = NULL;
-
-        system->filter = kzalloc(sizeof(struct event_filter), GFP_KERNEL);
-        if (!system->filter) {
-                pr_warning("Could not allocate filter for subsystem "
-                           "'%s'\n", name);
-                return system->entry;
-        }
+        dir->tr = tr;
+        dir->ref_count = 1;
+        dir->nr_events = 1;
+        dir->subsystem = system;
+        file->system = dir;
 
-        entry = debugfs_create_file("filter", 0644, system->entry, system,
+        entry = debugfs_create_file("filter", 0644, dir->entry, dir,
                                     &ftrace_subsystem_filter_fops);
         if (!entry) {
                 kfree(system->filter);
                 system->filter = NULL;
-                pr_warning("Could not create debugfs "
-                           "'%s/filter' entry\n", name);
+                pr_warning("Could not create debugfs '%s/filter' entry\n", name);
         }
 
-        trace_create_file("enable", 0644, system->entry, system,
+        trace_create_file("enable", 0644, dir->entry, dir,
                           &ftrace_system_enable_fops);
 
-        return system->entry;
+        list_add(&dir->list, &tr->systems);
+
+        return dir->entry;
+
+ out_free:
+        kfree(dir);
+ out_fail:
+        /* Only print this message if failed on memory allocation */
+        if (!dir || !system)
+                pr_warning("No memory to create event subsystem %s\n",
+                           name);
+        return NULL;
 }
 
 static int
-event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,
+event_create_dir(struct dentry *parent,
+                 struct ftrace_event_file *file,
                  const struct file_operations *id,
                  const struct file_operations *enable,
                  const struct file_operations *filter,
                  const struct file_operations *format)
 {
+        struct ftrace_event_call *call = file->event_call;
+        struct trace_array *tr = file->tr;
         struct list_head *head;
+        struct dentry *d_events;
         int ret;
 
         /*
          * If the trace point header did not define TRACE_SYSTEM
          * then the system would be called "TRACE_SYSTEM".
          */
-        if (strcmp(call->class->system, TRACE_SYSTEM) != 0)
-                d_events = event_subsystem_dir(call->class->system, d_events);
-
-        call->dir = debugfs_create_dir(call->name, d_events);
-        if (!call->dir) {
-                pr_warning("Could not create debugfs "
-                           "'%s' directory\n", call->name);
+        if (strcmp(call->class->system, TRACE_SYSTEM) != 0) {
+                d_events = event_subsystem_dir(tr, call->class->system, file, parent);
+                if (!d_events)
+                        return -ENOMEM;
+        } else
+                d_events = parent;
+
+        file->dir = debugfs_create_dir(call->name, d_events);
+        if (!file->dir) {
+                pr_warning("Could not create debugfs '%s' directory\n",
+                           call->name);
                 return -1;
         }
 
         if (call->class->reg && !(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE))
-                trace_create_file("enable", 0644, call->dir, call,
+                trace_create_file("enable", 0644, file->dir, file,
                                   enable);
 
 #ifdef CONFIG_PERF_EVENTS
         if (call->event.type && call->class->reg)
-                trace_create_file("id", 0444, call->dir, call,
+                trace_create_file("id", 0444, file->dir, call,
                                   id);
 #endif
 
@@ -1196,23 +1346,76 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,
                 if (ret < 0) {
                         pr_warning("Could not initialize trace point"
                                    " events/%s\n", call->name);
-                        return ret;
+                        return -1;
                 }
         }
-        trace_create_file("filter", 0644, call->dir, call,
+        trace_create_file("filter", 0644, file->dir, call,
                           filter);
 
-        trace_create_file("format", 0444, call->dir, call,
+        trace_create_file("format", 0444, file->dir, call,
                           format);
 
         return 0;
 }
 
+static void remove_subsystem(struct ftrace_subsystem_dir *dir)
+{
+        if (!dir)
+                return;
+
+        if (!--dir->nr_events) {
+                debugfs_remove_recursive(dir->entry);
+                list_del(&dir->list);
+                __put_system_dir(dir);
+        }
+}
+
+static void remove_event_from_tracers(struct ftrace_event_call *call)
+{
+        struct ftrace_event_file *file;
+        struct trace_array *tr;
+
+        do_for_each_event_file_safe(tr, file) {
+
+                if (file->event_call != call)
+                        continue;
+
+                list_del(&file->list);
+                debugfs_remove_recursive(file->dir);
+                remove_subsystem(file->system);
+                kfree(file);
+
+                /*
+                 * The do_for_each_event_file_safe() is
+                 * a double loop. After finding the call for this
+                 * trace_array, we use break to jump to the next
+                 * trace_array.
+                 */
+                break;
+        } while_for_each_event_file();
+}
+
 static void event_remove(struct ftrace_event_call *call)
 {
-        ftrace_event_enable_disable(call, 0);
+        struct trace_array *tr;
+        struct ftrace_event_file *file;
+
+        do_for_each_event_file(tr, file) {
+                if (file->event_call != call)
+                        continue;
+                ftrace_event_enable_disable(file, 0);
+                /*
+                 * The do_for_each_event_file() is
+                 * a double loop. After finding the call for this
+                 * trace_array, we use break to jump to the next
+                 * trace_array.
+                 */
+                break;
+        } while_for_each_event_file();
+
         if (call->event.funcs)
                 __unregister_ftrace_event(&call->event);
+        remove_event_from_tracers(call);
         list_del(&call->list);
 }
 
@@ -1234,61 +1437,58 @@ static int event_init(struct ftrace_event_call *call)
 }
 
 static int
-__trace_add_event_call(struct ftrace_event_call *call, struct module *mod,
-                       const struct file_operations *id,
-                       const struct file_operations *enable,
-                       const struct file_operations *filter,
-                       const struct file_operations *format)
+__register_event(struct ftrace_event_call *call, struct module *mod)
 {
-        struct dentry *d_events;
         int ret;
 
         ret = event_init(call);
         if (ret < 0)
                 return ret;
 
-        d_events = event_trace_events_dir();
-        if (!d_events)
-                return -ENOENT;
-
-        ret = event_create_dir(call, d_events, id, enable, filter, format);
-        if (!ret)
-                list_add(&call->list, &ftrace_events);
+        list_add(&call->list, &ftrace_events);
         call->mod = mod;
 
-        return ret;
+        return 0;
 }
 
+/* Add an event to a trace directory */
+static int
+__trace_add_new_event(struct ftrace_event_call *call,
+                      struct trace_array *tr,
+                      const struct file_operations *id,
+                      const struct file_operations *enable,
+                      const struct file_operations *filter,
+                      const struct file_operations *format)
+{
+        struct ftrace_event_file *file;
+
+        file = kzalloc(sizeof(*file), GFP_KERNEL);
+        if (!file)
+                return -ENOMEM;
+
+        file->event_call = call;
+        file->tr = tr;
+        list_add(&file->list, &tr->events);
+
+        return event_create_dir(tr->event_dir, file, id, enable, filter, format);
+}
+
+struct ftrace_module_file_ops;
+static void __add_event_to_tracers(struct ftrace_event_call *call,
+                                   struct ftrace_module_file_ops *file_ops);
+
 /* Add an additional event_call dynamically */
 int trace_add_event_call(struct ftrace_event_call *call)
 {
         int ret;
         mutex_lock(&event_mutex);
-        ret = __trace_add_event_call(call, NULL, &ftrace_event_id_fops,
-                                     &ftrace_enable_fops,
-                                     &ftrace_event_filter_fops,
-                                     &ftrace_event_format_fops);
-        mutex_unlock(&event_mutex);
-        return ret;
-}
 
-static void remove_subsystem_dir(const char *name)
-{
-        struct event_subsystem *system;
+        ret = __register_event(call, NULL);
+        if (ret >= 0)
+                __add_event_to_tracers(call, NULL);
 
-        if (strcmp(name, TRACE_SYSTEM) == 0)
-                return;
-
-        list_for_each_entry(system, &event_subsystems, list) {
-                if (strcmp(system->name, name) == 0) {
-                        if (!--system->nr_events) {
-                                debugfs_remove_recursive(system->entry);
-                                list_del(&system->list);
-                                __put_system(system);
-                        }
-                        break;
-                }
-        }
+        mutex_unlock(&event_mutex);
+        return ret;
 }
 
 /*
@@ -1299,8 +1499,6 @@ static void __trace_remove_event_call(struct ftrace_event_call *call)
         event_remove(call);
         trace_destroy_fields(call);
         destroy_preds(call);
-        debugfs_remove_recursive(call->dir);
-        remove_subsystem_dir(call->class->system);
 }
 
 /* Remove an event_call */
@@ -1335,6 +1533,17 @@ struct ftrace_module_file_ops {
         struct file_operations          filter;
 };
 
+static struct ftrace_module_file_ops *find_ftrace_file_ops(struct module *mod)
+{
+        struct ftrace_module_file_ops *file_ops;
+
+        list_for_each_entry(file_ops, &ftrace_module_file_list, list) {
+                if (file_ops->mod == mod)
+                        return file_ops;
+        }
+        return NULL;
+}
+
 static struct ftrace_module_file_ops *
 trace_create_file_ops(struct module *mod)
 {
@@ -1386,9 +1595,8 @@ static void trace_module_add_events(struct module *mod)
                 return;
 
         for_each_event(call, start, end) {
-                __trace_add_event_call(*call, mod,
-                                       &file_ops->id, &file_ops->enable,
-                                       &file_ops->filter, &file_ops->format);
+                __register_event(*call, mod);
+                __add_event_to_tracers(*call, file_ops);
         }
 }
 
@@ -1444,6 +1652,10 @@ static int trace_module_notify(struct notifier_block *self,
         return 0;
 }
 #else
+static struct ftrace_module_file_ops *find_ftrace_file_ops(struct module *mod)
+{
+        return NULL;
+}
 static int trace_module_notify(struct notifier_block *self,
                                unsigned long val, void *data)
 {
@@ -1451,6 +1663,72 @@ static int trace_module_notify(struct notifier_block *self,
 }
 #endif /* CONFIG_MODULES */
 
+/* Create a new event directory structure for a trace directory. */
+static void
+__trace_add_event_dirs(struct trace_array *tr)
+{
+        struct ftrace_module_file_ops *file_ops = NULL;
+        struct ftrace_event_call *call;
+        int ret;
+
+        list_for_each_entry(call, &ftrace_events, list) {
+                if (call->mod) {
+                        /*
+                         * Directories for events by modules need to
+                         * keep module ref counts when opened (as we don't
+                         * want the module to disappear when reading one
+                         * of these files). The file_ops keep account of
+                         * the module ref count.
+                         *
+                         * As event_calls are added in groups by module,
+                         * when we find one file_ops, we don't need to search for
+                         * each call in that module, as the rest should be the
+                         * same. Only search for a new one if the last one did
+                         * not match.
+                         */
+                        if (!file_ops || call->mod != file_ops->mod)
+                                file_ops = find_ftrace_file_ops(call->mod);
+                        if (!file_ops)
+                                continue; /* Warn? */
+                        ret = __trace_add_new_event(call, tr,
+                                        &file_ops->id, &file_ops->enable,
+                                        &file_ops->filter, &file_ops->format);
+                        if (ret < 0)
+                                pr_warning("Could not create directory for event %s\n",
+                                           call->name);
+                        continue;
+                }
+                ret = __trace_add_new_event(call, tr,
+                                            &ftrace_event_id_fops,
+                                            &ftrace_enable_fops,
+                                            &ftrace_event_filter_fops,
+                                            &ftrace_event_format_fops);
+                if (ret < 0)
+                        pr_warning("Could not create directory for event %s\n",
+                                   call->name);
+        }
+}
+
+static void
+__add_event_to_tracers(struct ftrace_event_call *call,
+                       struct ftrace_module_file_ops *file_ops)
+{
+        struct trace_array *tr;
+
+        list_for_each_entry(tr, &ftrace_trace_arrays, list) {
+                if (file_ops)
+                        __trace_add_new_event(call, tr,
+                                              &file_ops->id, &file_ops->enable,
+                                              &file_ops->filter, &file_ops->format);
+                else
+                        __trace_add_new_event(call, tr,
+                                              &ftrace_event_id_fops,
+                                              &ftrace_enable_fops,
+                                              &ftrace_event_filter_fops,
+                                              &ftrace_event_format_fops);
+        }
+}
+
 static struct notifier_block trace_module_nb = {
         .notifier_call = trace_module_notify,
         .priority = 0,
@@ -1471,8 +1749,43 @@ static __init int setup_trace_event(char *str)
 }
 __setup("trace_event=", setup_trace_event);
 
+int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr)
+{
+        struct dentry *d_events;
+        struct dentry *entry;
+
+        entry = debugfs_create_file("set_event", 0644, parent,
+                                    tr, &ftrace_set_event_fops);
+        if (!entry) {
+                pr_warning("Could not create debugfs 'set_event' entry\n");
+                return -ENOMEM;
+        }
+
+        d_events = debugfs_create_dir("events", parent);
+        if (!d_events)
+                pr_warning("Could not create debugfs 'events' directory\n");
+
+        /* ring buffer internal formats */
+        trace_create_file("header_page", 0444, d_events,
+                          ring_buffer_print_page_header,
+                          &ftrace_show_header_fops);
+
+        trace_create_file("header_event", 0444, d_events,
+                          ring_buffer_print_entry_header,
+                          &ftrace_show_header_fops);
+
+        trace_create_file("enable", 0644, d_events,
+                          tr, &ftrace_tr_enable_fops);
+
+        tr->event_dir = d_events;
+        __trace_add_event_dirs(tr);
+
+        return 0;
+}
+
 static __init int event_trace_enable(void)
 {
+        struct trace_array *tr = top_trace_array();
         struct ftrace_event_call **iter, *call;
         char *buf = bootup_event_buf;
         char *token;
@@ -1494,7 +1807,7 @@ static __init int event_trace_enable(void)
                 if (!*token)
                         continue;
 
-                ret = ftrace_set_clr_event(token, 1);
+                ret = ftrace_set_clr_event(tr, token, 1);
                 if (ret)
                         pr_warn("Failed to enable trace event: %s\n", token);
         }
@@ -1506,61 +1819,29 @@ static __init int event_trace_enable(void)
 
 static __init int event_trace_init(void)
 {
-        struct ftrace_event_call *call;
+        struct trace_array *tr;
         struct dentry *d_tracer;
         struct dentry *entry;
-        struct dentry *d_events;
         int ret;
 
+        tr = top_trace_array();
+
         d_tracer = tracing_init_dentry();
         if (!d_tracer)
                 return 0;
 
         entry = debugfs_create_file("available_events", 0444, d_tracer,
-                                    NULL, &ftrace_avail_fops);
+                                    tr, &ftrace_avail_fops);
         if (!entry)
                 pr_warning("Could not create debugfs "
                            "'available_events' entry\n");
 
-        entry = debugfs_create_file("set_event", 0644, d_tracer,
-                                    NULL, &ftrace_set_event_fops);
-        if (!entry)
-                pr_warning("Could not create debugfs "
-                           "'set_event' entry\n");
-
-        d_events = event_trace_events_dir();
-        if (!d_events)
-                return 0;
-
-        /* ring buffer internal formats */
-        trace_create_file("header_page", 0444, d_events,
-                          ring_buffer_print_page_header,
-                          &ftrace_show_header_fops);
-
-        trace_create_file("header_event", 0444, d_events,
-                          ring_buffer_print_entry_header,
-                          &ftrace_show_header_fops);
-
-        trace_create_file("enable", 0644, d_events,
-                          NULL, &ftrace_system_enable_fops);
-
         if (trace_define_common_fields())
                 pr_warning("tracing: Failed to allocate common fields");
 
-        /*
-         * Early initialization already enabled ftrace event.
-         * Now it's only necessary to create the event directory.
-         */
-        list_for_each_entry(call, &ftrace_events, list) {
-
-                ret = event_create_dir(call, d_events,
-                                       &ftrace_event_id_fops,
-                                       &ftrace_enable_fops,
-                                       &ftrace_event_filter_fops,
-                                       &ftrace_event_format_fops);
-                if (ret < 0)
-                        event_remove(call);
-        }
+        ret = event_trace_add_tracer(d_tracer, tr);
+        if (ret)
+                return ret;
 
         ret = register_module_notifier(&trace_module_nb);
         if (ret)
@@ -1627,13 +1908,20 @@ static __init void event_test_stuff(void)
  */
 static __init void event_trace_self_tests(void)
 {
+        struct ftrace_subsystem_dir *dir;
+        struct ftrace_event_file *file;
         struct ftrace_event_call *call;
         struct event_subsystem *system;
+        struct trace_array *tr;
         int ret;
 
+        tr = top_trace_array();
+
         pr_info("Running tests on trace events:\n");
 
-        list_for_each_entry(call, &ftrace_events, list) {
+        list_for_each_entry(file, &tr->events, list) {
+
+                call = file->event_call;
 
                 /* Only test those that have a probe */
                 if (!call->class || !call->class->probe)
@@ -1657,15 +1945,15 @@ static __init void event_trace_self_tests(void)
                  * If an event is already enabled, someone is using
                  * it and the self test should not be on.
                  */
-                if (call->flags & TRACE_EVENT_FL_ENABLED) {
+                if (file->flags & FTRACE_EVENT_FL_ENABLED) {
                         pr_warning("Enabled event during self test!\n");
                         WARN_ON_ONCE(1);
                         continue;
                 }
 
-                ftrace_event_enable_disable(call, 1);
+                ftrace_event_enable_disable(file, 1);
                 event_test_stuff();
-                ftrace_event_enable_disable(call, 0);
+                ftrace_event_enable_disable(file, 0);
 
                 pr_cont("OK\n");
         }
@@ -1674,7 +1962,9 @@ static __init void event_trace_self_tests(void)
 
         pr_info("Running tests on trace event systems:\n");
 
-        list_for_each_entry(system, &event_subsystems, list) {
+        list_for_each_entry(dir, &tr->systems, list) {
+
+                system = dir->subsystem;
 
                 /* the ftrace system is special, skip it */
                 if (strcmp(system->name, "ftrace") == 0)
@@ -1682,7 +1972,7 @@ static __init void event_trace_self_tests(void)
 
                 pr_info("Testing event system %s: ", system->name);
 
-                ret = __ftrace_set_clr_event(NULL, system->name, NULL, 1);
+                ret = __ftrace_set_clr_event(tr, NULL, system->name, NULL, 1);
                 if (WARN_ON_ONCE(ret)) {
                         pr_warning("error enabling system %s\n",
                                    system->name);
@@ -1691,7 +1981,7 @@ static __init void event_trace_self_tests(void)
 
                 event_test_stuff();
 
-                ret = __ftrace_set_clr_event(NULL, system->name, NULL, 0);
+                ret = __ftrace_set_clr_event(tr, NULL, system->name, NULL, 0);
                 if (WARN_ON_ONCE(ret)) {
                         pr_warning("error disabling system %s\n",
                                    system->name);
@@ -1706,7 +1996,7 @@ static __init void event_trace_self_tests(void)
         pr_info("Running tests on all trace events:\n");
         pr_info("Testing all events: ");
 
-        ret = __ftrace_set_clr_event(NULL, NULL, NULL, 1);
+        ret = __ftrace_set_clr_event(tr, NULL, NULL, NULL, 1);
         if (WARN_ON_ONCE(ret)) {
                 pr_warning("error enabling all events\n");
                 return;
@@ -1715,7 +2005,7 @@ static __init void event_trace_self_tests(void)
         event_test_stuff();
 
         /* reset sysname */
-        ret = __ftrace_set_clr_event(NULL, NULL, NULL, 0);
+        ret = __ftrace_set_clr_event(tr, NULL, NULL, NULL, 0);
         if (WARN_ON_ONCE(ret)) {
                 pr_warning("error disabling all events\n");
                 return;