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>
This commit is contained in:
Steven Rostedt (Red Hat)
Steven Rostedt
parent
417944c4c7
commit
3cd715de26
1 changed files with 279 additions and 0 deletions
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@ -1798,6 +1798,283 @@ __trace_add_event_dirs(struct trace_array *tr)
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}
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}
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#ifdef CONFIG_DYNAMIC_FTRACE
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/* Avoid typos */
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#define ENABLE_EVENT_STR "enable_event"
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#define DISABLE_EVENT_STR "disable_event"
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struct event_probe_data {
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struct ftrace_event_file *file;
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unsigned long count;
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int ref;
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bool enable;
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};
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static struct ftrace_event_file *
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find_event_file(struct trace_array *tr, const char *system, const char *event)
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{
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struct ftrace_event_file *file;
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struct ftrace_event_call *call;
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list_for_each_entry(file, &tr->events, list) {
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call = file->event_call;
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if (!call->name || !call->class || !call->class->reg)
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continue;
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if (call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)
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continue;
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if (strcmp(event, call->name) == 0 &&
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strcmp(system, call->class->system) == 0)
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return file;
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}
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return NULL;
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}
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static void
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event_enable_probe(unsigned long ip, unsigned long parent_ip, void **_data)
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{
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struct event_probe_data **pdata = (struct event_probe_data **)_data;
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struct event_probe_data *data = *pdata;
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if (!data)
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return;
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if (data->enable)
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clear_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &data->file->flags);
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else
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set_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &data->file->flags);
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}
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static void
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event_enable_count_probe(unsigned long ip, unsigned long parent_ip, void **_data)
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{
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struct event_probe_data **pdata = (struct event_probe_data **)_data;
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struct event_probe_data *data = *pdata;
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if (!data)
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return;
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if (!data->count)
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return;
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/* Skip if the event is in a state we want to switch to */
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if (data->enable == !(data->file->flags & FTRACE_EVENT_FL_SOFT_DISABLED))
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return;
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if (data->count != -1)
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(data->count)--;
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event_enable_probe(ip, parent_ip, _data);
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}
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static int
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event_enable_print(struct seq_file *m, unsigned long ip,
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struct ftrace_probe_ops *ops, void *_data)
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{
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struct event_probe_data *data = _data;
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seq_printf(m, "%ps:", (void *)ip);
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seq_printf(m, "%s:%s:%s",
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data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR,
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data->file->event_call->class->system,
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data->file->event_call->name);
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if (data->count == -1)
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seq_printf(m, ":unlimited\n");
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else
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seq_printf(m, ":count=%ld\n", data->count);
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return 0;
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}
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static int
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event_enable_init(struct ftrace_probe_ops *ops, unsigned long ip,
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void **_data)
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{
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struct event_probe_data **pdata = (struct event_probe_data **)_data;
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struct event_probe_data *data = *pdata;
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data->ref++;
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return 0;
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}
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static void
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event_enable_free(struct ftrace_probe_ops *ops, unsigned long ip,
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void **_data)
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{
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struct event_probe_data **pdata = (struct event_probe_data **)_data;
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struct event_probe_data *data = *pdata;
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if (WARN_ON_ONCE(data->ref <= 0))
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return;
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data->ref--;
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if (!data->ref) {
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/* Remove the SOFT_MODE flag */
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__ftrace_event_enable_disable(data->file, 0, 1);
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module_put(data->file->event_call->mod);
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kfree(data);
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}
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*pdata = NULL;
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}
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static struct ftrace_probe_ops event_enable_probe_ops = {
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.func = event_enable_probe,
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.print = event_enable_print,
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.init = event_enable_init,
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.free = event_enable_free,
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};
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static struct ftrace_probe_ops event_enable_count_probe_ops = {
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.func = event_enable_count_probe,
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.print = event_enable_print,
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.init = event_enable_init,
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.free = event_enable_free,
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};
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static struct ftrace_probe_ops event_disable_probe_ops = {
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.func = event_enable_probe,
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.print = event_enable_print,
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.init = event_enable_init,
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.free = event_enable_free,
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};
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static struct ftrace_probe_ops event_disable_count_probe_ops = {
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.func = event_enable_count_probe,
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.print = event_enable_print,
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.init = event_enable_init,
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.free = event_enable_free,
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};
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static int
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event_enable_func(struct ftrace_hash *hash,
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char *glob, char *cmd, char *param, int enabled)
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{
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struct trace_array *tr = top_trace_array();
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struct ftrace_event_file *file;
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struct ftrace_probe_ops *ops;
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struct event_probe_data *data;
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const char *system;
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const char *event;
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char *number;
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bool enable;
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int ret;
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/* hash funcs only work with set_ftrace_filter */
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if (!enabled)
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return -EINVAL;
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if (!param)
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return -EINVAL;
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system = strsep(¶m, ":");
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if (!param)
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return -EINVAL;
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event = strsep(¶m, ":");
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mutex_lock(&event_mutex);
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ret = -EINVAL;
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file = find_event_file(tr, system, event);
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if (!file)
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goto out;
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enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
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if (enable)
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ops = param ? &event_enable_count_probe_ops : &event_enable_probe_ops;
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else
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ops = param ? &event_disable_count_probe_ops : &event_disable_probe_ops;
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if (glob[0] == '!') {
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unregister_ftrace_function_probe_func(glob+1, ops);
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ret = 0;
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goto out;
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}
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ret = -ENOMEM;
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data = kzalloc(sizeof(*data), GFP_KERNEL);
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if (!data)
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goto out;
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data->enable = enable;
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data->count = -1;
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data->file = file;
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if (!param)
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goto out_reg;
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number = strsep(¶m, ":");
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ret = -EINVAL;
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if (!strlen(number))
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goto out_free;
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/*
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* We use the callback data field (which is a pointer)
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* as our counter.
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*/
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ret = kstrtoul(number, 0, &data->count);
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if (ret)
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goto out_free;
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out_reg:
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/* Don't let event modules unload while probe registered */
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ret = try_module_get(file->event_call->mod);
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if (!ret)
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goto out_free;
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ret = __ftrace_event_enable_disable(file, 1, 1);
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if (ret < 0)
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goto out_put;
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ret = register_ftrace_function_probe(glob, ops, data);
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if (!ret)
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goto out_disable;
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out:
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mutex_unlock(&event_mutex);
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return ret;
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out_disable:
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__ftrace_event_enable_disable(file, 0, 1);
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out_put:
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module_put(file->event_call->mod);
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out_free:
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kfree(data);
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goto out;
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}
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static struct ftrace_func_command event_enable_cmd = {
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.name = ENABLE_EVENT_STR,
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.func = event_enable_func,
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};
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static struct ftrace_func_command event_disable_cmd = {
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.name = DISABLE_EVENT_STR,
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.func = event_enable_func,
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};
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static __init int register_event_cmds(void)
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{
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int ret;
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ret = register_ftrace_command(&event_enable_cmd);
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if (WARN_ON(ret < 0))
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return ret;
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ret = register_ftrace_command(&event_disable_cmd);
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if (WARN_ON(ret < 0))
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unregister_ftrace_command(&event_enable_cmd);
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return ret;
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}
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#else
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static inline int register_event_cmds(void) { return 0; }
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#endif /* CONFIG_DYNAMIC_FTRACE */
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/*
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* The top level array has already had its ftrace_event_file
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* descriptors created in order to allow for early events to
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@ -2058,6 +2335,8 @@ static __init int event_trace_enable(void)
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trace_printk_start_comm();
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register_event_cmds();
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return 0;
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}
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