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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2013-03-12 19:35:13 -0400
committerSteven Rostedt <rostedt@goodmis.org>2013-03-15 00:36:04 -0400
commit3cd715de261182413b3487abfffe1b6af41b81b3 (patch)
tree14d9a48d2aa31eb1ad387477376e41f25031238f
parent417944c4c7a0f657158d0515f3b8e8c043fd788f (diff)
tracing: Add function probe triggers to enable/disable events
Add triggers to function tracer that lets an event get enabled or disabled when a function is called: format is: <function>:enable_event:<system>:<event>[:<count>] <function>:disable_event:<system>:<event>[:<count>] echo 'schedule:enable_event:sched:sched_switch' > /debug/tracing/set_ftrace_filter Every time schedule is called, it will enable the sched_switch event. echo 'schedule:disable_event:sched:sched_switch:2' > /debug/tracing/set_ftrace_filter The first two times schedule is called while the sched_switch event is enabled, it will disable it. It will not count for a time that the event is already disabled (or enabled for enable_event). [ fixed return without mutex_unlock() - thanks to Dan Carpenter and smatch ] Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r--kernel/trace/trace_events.c279
1 files changed, 279 insertions, 0 deletions
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 106640b..c636523 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1798,6 +1798,283 @@ __trace_add_event_dirs(struct trace_array *tr)
}
}
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+/* Avoid typos */
+#define ENABLE_EVENT_STR "enable_event"
+#define DISABLE_EVENT_STR "disable_event"
+
+struct event_probe_data {
+ struct ftrace_event_file *file;
+ unsigned long count;
+ int ref;
+ bool enable;
+};
+
+static struct ftrace_event_file *
+find_event_file(struct trace_array *tr, const char *system, const char *event)
+{
+ struct ftrace_event_file *file;
+ struct ftrace_event_call *call;
+
+ list_for_each_entry(file, &tr->events, list) {
+
+ call = file->event_call;
+
+ if (!call->name || !call->class || !call->class->reg)
+ continue;
+
+ if (call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)
+ continue;
+
+ if (strcmp(event, call->name) == 0 &&
+ strcmp(system, call->class->system) == 0)
+ return file;
+ }
+ return NULL;
+}
+
+static void
+event_enable_probe(unsigned long ip, unsigned long parent_ip, void **_data)
+{
+ struct event_probe_data **pdata = (struct event_probe_data **)_data;
+ struct event_probe_data *data = *pdata;
+
+ if (!data)
+ return;
+
+ if (data->enable)
+ clear_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &data->file->flags);
+ else
+ set_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &data->file->flags);
+}
+
+static void
+event_enable_count_probe(unsigned long ip, unsigned long parent_ip, void **_data)
+{
+ struct event_probe_data **pdata = (struct event_probe_data **)_data;
+ struct event_probe_data *data = *pdata;
+
+ if (!data)
+ return;
+
+ if (!data->count)
+ return;
+
+ /* Skip if the event is in a state we want to switch to */
+ if (data->enable == !(data->file->flags & FTRACE_EVENT_FL_SOFT_DISABLED))
+ return;
+
+ if (data->count != -1)
+ (data->count)--;
+
+ event_enable_probe(ip, parent_ip, _data);
+}
+
+static int
+event_enable_print(struct seq_file *m, unsigned long ip,
+ struct ftrace_probe_ops *ops, void *_data)
+{
+ struct event_probe_data *data = _data;
+
+ seq_printf(m, "%ps:", (void *)ip);
+
+ seq_printf(m, "%s:%s:%s",
+ data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR,
+ data->file->event_call->class->system,
+ data->file->event_call->name);
+
+ if (data->count == -1)
+ seq_printf(m, ":unlimited\n");
+ else
+ seq_printf(m, ":count=%ld\n", data->count);
+
+ return 0;
+}
+
+static int
+event_enable_init(struct ftrace_probe_ops *ops, unsigned long ip,
+ void **_data)
+{
+ struct event_probe_data **pdata = (struct event_probe_data **)_data;
+ struct event_probe_data *data = *pdata;
+
+ data->ref++;
+ return 0;
+}
+
+static void
+event_enable_free(struct ftrace_probe_ops *ops, unsigned long ip,
+ void **_data)
+{
+ struct event_probe_data **pdata = (struct event_probe_data **)_data;
+ struct event_probe_data *data = *pdata;
+
+ if (WARN_ON_ONCE(data->ref <= 0))
+ return;
+
+ data->ref--;
+ if (!data->ref) {
+ /* Remove the SOFT_MODE flag */
+ __ftrace_event_enable_disable(data->file, 0, 1);
+ module_put(data->file->event_call->mod);
+ kfree(data);
+ }
+ *pdata = NULL;
+}
+
+static struct ftrace_probe_ops event_enable_probe_ops = {
+ .func = event_enable_probe,
+ .print = event_enable_print,
+ .init = event_enable_init,
+ .free = event_enable_free,
+};
+
+static struct ftrace_probe_ops event_enable_count_probe_ops = {
+ .func = event_enable_count_probe,
+ .print = event_enable_print,
+ .init = event_enable_init,
+ .free = event_enable_free,
+};
+
+static struct ftrace_probe_ops event_disable_probe_ops = {
+ .func = event_enable_probe,
+ .print = event_enable_print,
+ .init = event_enable_init,
+ .free = event_enable_free,
+};
+
+static struct ftrace_probe_ops event_disable_count_probe_ops = {
+ .func = event_enable_count_probe,
+ .print = event_enable_print,
+ .init = event_enable_init,
+ .free = event_enable_free,
+};
+
+static int
+event_enable_func(struct ftrace_hash *hash,
+ char *glob, char *cmd, char *param, int enabled)
+{
+ struct trace_array *tr = top_trace_array();
+ struct ftrace_event_file *file;
+ struct ftrace_probe_ops *ops;
+ struct event_probe_data *data;
+ const char *system;
+ const char *event;
+ char *number;
+ bool enable;
+ int ret;
+
+ /* hash funcs only work with set_ftrace_filter */
+ if (!enabled)
+ return -EINVAL;
+
+ if (!param)
+ return -EINVAL;
+
+ system = strsep(&param, ":");
+ if (!param)
+ return -EINVAL;
+
+ event = strsep(&param, ":");
+
+ mutex_lock(&event_mutex);
+
+ ret = -EINVAL;
+ file = find_event_file(tr, system, event);
+ if (!file)
+ goto out;
+
+ enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
+
+ if (enable)
+ ops = param ? &event_enable_count_probe_ops : &event_enable_probe_ops;
+ else
+ ops = param ? &event_disable_count_probe_ops : &event_disable_probe_ops;
+
+ if (glob[0] == '!') {
+ unregister_ftrace_function_probe_func(glob+1, ops);
+ ret = 0;
+ goto out;
+ }
+
+ ret = -ENOMEM;
+ data = kzalloc(sizeof(*data), GFP_KERNEL);
+ if (!data)
+ goto out;
+
+ data->enable = enable;
+ data->count = -1;
+ data->file = file;
+
+ if (!param)
+ goto out_reg;
+
+ number = strsep(&param, ":");
+
+ 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, &data->count);
+ if (ret)
+ goto out_free;
+
+ out_reg:
+ /* Don't let event modules unload while probe registered */
+ ret = try_module_get(file->event_call->mod);
+ if (!ret)
+ goto out_free;
+
+ ret = __ftrace_event_enable_disable(file, 1, 1);
+ if (ret < 0)
+ goto out_put;
+ ret = register_ftrace_function_probe(glob, ops, data);
+ if (!ret)
+ goto out_disable;
+ out:
+ mutex_unlock(&event_mutex);
+ return ret;
+
+ out_disable:
+ __ftrace_event_enable_disable(file, 0, 1);
+ out_put:
+ module_put(file->event_call->mod);
+ out_free:
+ kfree(data);
+ goto out;
+}
+
+static struct ftrace_func_command event_enable_cmd = {
+ .name = ENABLE_EVENT_STR,
+ .func = event_enable_func,
+};
+
+static struct ftrace_func_command event_disable_cmd = {
+ .name = DISABLE_EVENT_STR,
+ .func = event_enable_func,
+};
+
+static __init int register_event_cmds(void)
+{
+ int ret;
+
+ ret = register_ftrace_command(&event_enable_cmd);
+ if (WARN_ON(ret < 0))
+ return ret;
+ ret = register_ftrace_command(&event_disable_cmd);
+ if (WARN_ON(ret < 0))
+ unregister_ftrace_command(&event_enable_cmd);
+ return ret;
+}
+#else
+static inline int register_event_cmds(void) { return 0; }
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
/*
* The top level array has already had its ftrace_event_file
* descriptors created in order to allow for early events to
@@ -2058,6 +2335,8 @@ static __init int event_trace_enable(void)
trace_printk_start_comm();
+ register_event_cmds();
+
return 0;
}