tracing: Add 'enable_event' and 'disable_event' event trigger commands
authorTom Zanussi <tom.zanussi@linux.intel.com>
Thu, 24 Oct 2013 13:59:28 +0000 (08:59 -0500)
committerSteven Rostedt <rostedt@goodmis.org>
Sun, 22 Dec 2013 03:02:16 +0000 (22:02 -0500)
Add 'enable_event' and 'disable_event' event_command commands.

enable_event and disable_event event triggers are added by the user
via these commands in a similar way and using practically the same
syntax as the analagous 'enable_event' and 'disable_event' ftrace
function commands, but instead of writing to the set_ftrace_filter
file, the enable_event and disable_event triggers are written to the
per-event 'trigger' files:

    echo 'enable_event:system:event' > .../othersys/otherevent/trigger
    echo 'disable_event:system:event' > .../othersys/otherevent/trigger

The above commands will enable or disable the 'system:event' trace
events whenever the othersys:otherevent events are hit.

This also adds a 'count' version that limits the number of times the
command will be invoked:

    echo 'enable_event:system:event:N' > .../othersys/otherevent/trigger
    echo 'disable_event:system:event:N' > .../othersys/otherevent/trigger

Where N is the number of times the command will be invoked.

The above commands will will enable or disable the 'system:event'
trace events whenever the othersys:otherevent events are hit, but only
N times.

This also makes the find_event_file() helper function extern, since
it's useful to use from other places, such as the event triggers code,
so make it accessible.

Link: http://lkml.kernel.org/r/f825f3048c3f6b026ee37ae5825f9fc373451828.1382622043.git.tom.zanussi@linux.intel.com
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
include/linux/ftrace_event.h
kernel/trace/trace.h
kernel/trace/trace_events.c
kernel/trace/trace_events_trigger.c

index 65caee4..2f73c39 100644 (file)
@@ -348,6 +348,7 @@ enum event_trigger_type {
        ETT_TRACE_ONOFF         = (1 << 0),
        ETT_SNAPSHOT            = (1 << 1),
        ETT_STACKTRACE          = (1 << 2),
+       ETT_EVENT_ENABLE        = (1 << 3),
 };
 
 extern void destroy_preds(struct ftrace_event_file *file);
index 50723e5..ccbd810 100644 (file)
@@ -1028,6 +1028,10 @@ extern void trace_event_enable_cmd_record(bool enable);
 extern int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr);
 extern int event_trace_del_tracer(struct trace_array *tr);
 
+extern struct ftrace_event_file *find_event_file(struct trace_array *tr,
+                                                const char *system,
+                                                const char *event);
+
 static inline void *event_file_data(struct file *filp)
 {
        return ACCESS_ONCE(file_inode(filp)->i_private);
index 442775c..9a974bd 100644 (file)
@@ -1868,7 +1868,7 @@ struct event_probe_data {
        bool                            enable;
 };
 
-static struct ftrace_event_file *
+struct ftrace_event_file *
 find_event_file(struct trace_array *tr, const char *system,  const char *event)
 {
        struct ftrace_event_file *file;
index a3bd1da..45e48b1 100644 (file)
@@ -864,6 +864,364 @@ static __init void unregister_trigger_traceon_traceoff_cmds(void)
        unregister_event_command(&trigger_traceoff_cmd);
 }
 
+/* Avoid typos */
+#define ENABLE_EVENT_STR       "enable_event"
+#define DISABLE_EVENT_STR      "disable_event"
+
+struct enable_trigger_data {
+       struct ftrace_event_file        *file;
+       bool                            enable;
+};
+
+static void
+event_enable_trigger(struct event_trigger_data *data)
+{
+       struct enable_trigger_data *enable_data = data->private_data;
+
+       if (enable_data->enable)
+               clear_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
+       else
+               set_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
+}
+
+static void
+event_enable_count_trigger(struct event_trigger_data *data)
+{
+       struct enable_trigger_data *enable_data = data->private_data;
+
+       if (!data->count)
+               return;
+
+       /* Skip if the event is in a state we want to switch to */
+       if (enable_data->enable == !(enable_data->file->flags & FTRACE_EVENT_FL_SOFT_DISABLED))
+               return;
+
+       if (data->count != -1)
+               (data->count)--;
+
+       event_enable_trigger(data);
+}
+
+static int
+event_enable_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
+                          struct event_trigger_data *data)
+{
+       struct enable_trigger_data *enable_data = data->private_data;
+
+       seq_printf(m, "%s:%s:%s",
+                  enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR,
+                  enable_data->file->event_call->class->system,
+                  enable_data->file->event_call->name);
+
+       if (data->count == -1)
+               seq_puts(m, ":unlimited");
+       else
+               seq_printf(m, ":count=%ld", data->count);
+
+       if (data->filter_str)
+               seq_printf(m, " if %s\n", data->filter_str);
+       else
+               seq_puts(m, "\n");
+
+       return 0;
+}
+
+static void
+event_enable_trigger_free(struct event_trigger_ops *ops,
+                         struct event_trigger_data *data)
+{
+       struct enable_trigger_data *enable_data = data->private_data;
+
+       if (WARN_ON_ONCE(data->ref <= 0))
+               return;
+
+       data->ref--;
+       if (!data->ref) {
+               /* Remove the SOFT_MODE flag */
+               trace_event_enable_disable(enable_data->file, 0, 1);
+               module_put(enable_data->file->event_call->mod);
+               trigger_data_free(data);
+               kfree(enable_data);
+       }
+}
+
+static struct event_trigger_ops event_enable_trigger_ops = {
+       .func                   = event_enable_trigger,
+       .print                  = event_enable_trigger_print,
+       .init                   = event_trigger_init,
+       .free                   = event_enable_trigger_free,
+};
+
+static struct event_trigger_ops event_enable_count_trigger_ops = {
+       .func                   = event_enable_count_trigger,
+       .print                  = event_enable_trigger_print,
+       .init                   = event_trigger_init,
+       .free                   = event_enable_trigger_free,
+};
+
+static struct event_trigger_ops event_disable_trigger_ops = {
+       .func                   = event_enable_trigger,
+       .print                  = event_enable_trigger_print,
+       .init                   = event_trigger_init,
+       .free                   = event_enable_trigger_free,
+};
+
+static struct event_trigger_ops event_disable_count_trigger_ops = {
+       .func                   = event_enable_count_trigger,
+       .print                  = event_enable_trigger_print,
+       .init                   = event_trigger_init,
+       .free                   = event_enable_trigger_free,
+};
+
+static int
+event_enable_trigger_func(struct event_command *cmd_ops,
+                         struct ftrace_event_file *file,
+                         char *glob, char *cmd, char *param)
+{
+       struct ftrace_event_file *event_enable_file;
+       struct enable_trigger_data *enable_data;
+       struct event_trigger_data *trigger_data;
+       struct event_trigger_ops *trigger_ops;
+       struct trace_array *tr = file->tr;
+       const char *system;
+       const char *event;
+       char *trigger;
+       char *number;
+       bool enable;
+       int ret;
+
+       if (!param)
+               return -EINVAL;
+
+       /* separate the trigger from the filter (s:e:n [if filter]) */
+       trigger = strsep(&param, " \t");
+       if (!trigger)
+               return -EINVAL;
+
+       system = strsep(&trigger, ":");
+       if (!trigger)
+               return -EINVAL;
+
+       event = strsep(&trigger, ":");
+
+       ret = -EINVAL;
+       event_enable_file = find_event_file(tr, system, event);
+       if (!event_enable_file)
+               goto out;
+
+       enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
+
+       trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
+
+       ret = -ENOMEM;
+       trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
+       if (!trigger_data)
+               goto out;
+
+       enable_data = kzalloc(sizeof(*enable_data), GFP_KERNEL);
+       if (!enable_data) {
+               kfree(trigger_data);
+               goto out;
+       }
+
+       trigger_data->count = -1;
+       trigger_data->ops = trigger_ops;
+       trigger_data->cmd_ops = cmd_ops;
+       INIT_LIST_HEAD(&trigger_data->list);
+       RCU_INIT_POINTER(trigger_data->filter, NULL);
+
+       enable_data->enable = enable;
+       enable_data->file = event_enable_file;
+       trigger_data->private_data = enable_data;
+
+       if (glob[0] == '!') {
+               cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
+               kfree(trigger_data);
+               kfree(enable_data);
+               ret = 0;
+               goto out;
+       }
+
+       if (trigger) {
+               number = strsep(&trigger, ":");
+
+               ret = -EINVAL;
+               if (!strlen(number))
+                       goto out_free;
+
+               /*
+                * We use the callback data field (which is a pointer)
+                * as our counter.
+                */
+               ret = kstrtoul(number, 0, &trigger_data->count);
+               if (ret)
+                       goto out_free;
+       }
+
+       if (!param) /* if param is non-empty, it's supposed to be a filter */
+               goto out_reg;
+
+       if (!cmd_ops->set_filter)
+               goto out_reg;
+
+       ret = cmd_ops->set_filter(param, trigger_data, file);
+       if (ret < 0)
+               goto out_free;
+
+ out_reg:
+       /* Don't let event modules unload while probe registered */
+       ret = try_module_get(event_enable_file->event_call->mod);
+       if (!ret) {
+               ret = -EBUSY;
+               goto out_free;
+       }
+
+       ret = trace_event_enable_disable(event_enable_file, 1, 1);
+       if (ret < 0)
+               goto out_put;
+       ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
+       /*
+        * The above returns on success the # of functions enabled,
+        * but if it didn't find any functions it returns zero.
+        * Consider no functions a failure too.
+        */
+       if (!ret) {
+               ret = -ENOENT;
+               goto out_disable;
+       } else if (ret < 0)
+               goto out_disable;
+       /* Just return zero, not the number of enabled functions */
+       ret = 0;
+ out:
+       return ret;
+
+ out_disable:
+       trace_event_enable_disable(event_enable_file, 0, 1);
+ out_put:
+       module_put(event_enable_file->event_call->mod);
+ out_free:
+       kfree(trigger_data);
+       kfree(enable_data);
+       goto out;
+}
+
+static int event_enable_register_trigger(char *glob,
+                                        struct event_trigger_ops *ops,
+                                        struct event_trigger_data *data,
+                                        struct ftrace_event_file *file)
+{
+       struct enable_trigger_data *enable_data = data->private_data;
+       struct enable_trigger_data *test_enable_data;
+       struct event_trigger_data *test;
+       int ret = 0;
+
+       list_for_each_entry_rcu(test, &file->triggers, list) {
+               test_enable_data = test->private_data;
+               if (test_enable_data &&
+                   (test_enable_data->file == enable_data->file)) {
+                       ret = -EEXIST;
+                       goto out;
+               }
+       }
+
+       if (data->ops->init) {
+               ret = data->ops->init(data->ops, data);
+               if (ret < 0)
+                       goto out;
+       }
+
+       list_add_rcu(&data->list, &file->triggers);
+       ret++;
+
+       if (trace_event_trigger_enable_disable(file, 1) < 0) {
+               list_del_rcu(&data->list);
+               ret--;
+       }
+out:
+       return ret;
+}
+
+static void event_enable_unregister_trigger(char *glob,
+                                           struct event_trigger_ops *ops,
+                                           struct event_trigger_data *test,
+                                           struct ftrace_event_file *file)
+{
+       struct enable_trigger_data *test_enable_data = test->private_data;
+       struct enable_trigger_data *enable_data;
+       struct event_trigger_data *data;
+       bool unregistered = false;
+
+       list_for_each_entry_rcu(data, &file->triggers, list) {
+               enable_data = data->private_data;
+               if (enable_data &&
+                   (enable_data->file == test_enable_data->file)) {
+                       unregistered = true;
+                       list_del_rcu(&data->list);
+                       trace_event_trigger_enable_disable(file, 0);
+                       break;
+               }
+       }
+
+       if (unregistered && data->ops->free)
+               data->ops->free(data->ops, data);
+}
+
+static struct event_trigger_ops *
+event_enable_get_trigger_ops(char *cmd, char *param)
+{
+       struct event_trigger_ops *ops;
+       bool enable;
+
+       enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
+
+       if (enable)
+               ops = param ? &event_enable_count_trigger_ops :
+                       &event_enable_trigger_ops;
+       else
+               ops = param ? &event_disable_count_trigger_ops :
+                       &event_disable_trigger_ops;
+
+       return ops;
+}
+
+static struct event_command trigger_enable_cmd = {
+       .name                   = ENABLE_EVENT_STR,
+       .trigger_type           = ETT_EVENT_ENABLE,
+       .func                   = event_enable_trigger_func,
+       .reg                    = event_enable_register_trigger,
+       .unreg                  = event_enable_unregister_trigger,
+       .get_trigger_ops        = event_enable_get_trigger_ops,
+};
+
+static struct event_command trigger_disable_cmd = {
+       .name                   = DISABLE_EVENT_STR,
+       .trigger_type           = ETT_EVENT_ENABLE,
+       .func                   = event_enable_trigger_func,
+       .reg                    = event_enable_register_trigger,
+       .unreg                  = event_enable_unregister_trigger,
+       .get_trigger_ops        = event_enable_get_trigger_ops,
+};
+
+static __init void unregister_trigger_enable_disable_cmds(void)
+{
+       unregister_event_command(&trigger_enable_cmd);
+       unregister_event_command(&trigger_disable_cmd);
+}
+
+static __init int register_trigger_enable_disable_cmds(void)
+{
+       int ret;
+
+       ret = register_event_command(&trigger_enable_cmd);
+       if (WARN_ON(ret < 0))
+               return ret;
+       ret = register_event_command(&trigger_disable_cmd);
+       if (WARN_ON(ret < 0))
+               unregister_trigger_enable_disable_cmds();
+
+       return ret;
+}
+
 static __init int register_trigger_traceon_traceoff_cmds(void)
 {
        int ret;
@@ -883,6 +1241,7 @@ __init int register_trigger_cmds(void)
        register_trigger_traceon_traceoff_cmds();
        register_trigger_snapshot_cmd();
        register_trigger_stacktrace_cmd();
+       register_trigger_enable_disable_cmds();
 
        return 0;
 }