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tracing: Add 'enable_event' and 'disable_event' event trigger commands
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>
This commit is contained in:
parent
f21ecbb35f
commit
7862ad1846
@ -348,6 +348,7 @@ enum event_trigger_type {
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ETT_TRACE_ONOFF = (1 << 0),
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ETT_SNAPSHOT = (1 << 1),
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ETT_STACKTRACE = (1 << 2),
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ETT_EVENT_ENABLE = (1 << 3),
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};
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extern void destroy_preds(struct ftrace_event_file *file);
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@ -1028,6 +1028,10 @@ extern void trace_event_enable_cmd_record(bool enable);
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extern int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr);
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extern int event_trace_del_tracer(struct trace_array *tr);
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extern struct ftrace_event_file *find_event_file(struct trace_array *tr,
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const char *system,
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const char *event);
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static inline void *event_file_data(struct file *filp)
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{
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return ACCESS_ONCE(file_inode(filp)->i_private);
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@ -1868,7 +1868,7 @@ struct event_probe_data {
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bool enable;
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};
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static struct ftrace_event_file *
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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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@ -864,6 +864,364 @@ static __init void unregister_trigger_traceon_traceoff_cmds(void)
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unregister_event_command(&trigger_traceoff_cmd);
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}
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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 enable_trigger_data {
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struct ftrace_event_file *file;
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bool enable;
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};
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static void
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event_enable_trigger(struct event_trigger_data *data)
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{
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struct enable_trigger_data *enable_data = data->private_data;
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if (enable_data->enable)
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clear_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
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else
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set_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
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}
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static void
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event_enable_count_trigger(struct event_trigger_data *data)
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{
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struct enable_trigger_data *enable_data = data->private_data;
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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 (enable_data->enable == !(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_trigger(data);
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}
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static int
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event_enable_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
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struct event_trigger_data *data)
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{
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struct enable_trigger_data *enable_data = data->private_data;
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seq_printf(m, "%s:%s:%s",
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enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR,
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enable_data->file->event_call->class->system,
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enable_data->file->event_call->name);
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if (data->count == -1)
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seq_puts(m, ":unlimited");
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else
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seq_printf(m, ":count=%ld", data->count);
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if (data->filter_str)
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seq_printf(m, " if %s\n", data->filter_str);
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else
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seq_puts(m, "\n");
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return 0;
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}
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static void
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event_enable_trigger_free(struct event_trigger_ops *ops,
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struct event_trigger_data *data)
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{
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struct enable_trigger_data *enable_data = data->private_data;
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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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trace_event_enable_disable(enable_data->file, 0, 1);
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module_put(enable_data->file->event_call->mod);
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trigger_data_free(data);
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kfree(enable_data);
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}
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}
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static struct event_trigger_ops event_enable_trigger_ops = {
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.func = event_enable_trigger,
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.print = event_enable_trigger_print,
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.init = event_trigger_init,
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.free = event_enable_trigger_free,
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};
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static struct event_trigger_ops event_enable_count_trigger_ops = {
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.func = event_enable_count_trigger,
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.print = event_enable_trigger_print,
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.init = event_trigger_init,
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.free = event_enable_trigger_free,
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};
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static struct event_trigger_ops event_disable_trigger_ops = {
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.func = event_enable_trigger,
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.print = event_enable_trigger_print,
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.init = event_trigger_init,
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.free = event_enable_trigger_free,
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};
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static struct event_trigger_ops event_disable_count_trigger_ops = {
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.func = event_enable_count_trigger,
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.print = event_enable_trigger_print,
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.init = event_trigger_init,
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.free = event_enable_trigger_free,
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};
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static int
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event_enable_trigger_func(struct event_command *cmd_ops,
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struct ftrace_event_file *file,
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char *glob, char *cmd, char *param)
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{
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struct ftrace_event_file *event_enable_file;
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struct enable_trigger_data *enable_data;
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struct event_trigger_data *trigger_data;
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struct event_trigger_ops *trigger_ops;
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struct trace_array *tr = file->tr;
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const char *system;
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const char *event;
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char *trigger;
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char *number;
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bool enable;
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int ret;
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if (!param)
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return -EINVAL;
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/* separate the trigger from the filter (s:e:n [if filter]) */
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trigger = strsep(¶m, " \t");
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if (!trigger)
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return -EINVAL;
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system = strsep(&trigger, ":");
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if (!trigger)
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return -EINVAL;
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event = strsep(&trigger, ":");
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ret = -EINVAL;
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event_enable_file = find_event_file(tr, system, event);
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if (!event_enable_file)
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goto out;
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enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
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trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
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ret = -ENOMEM;
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trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
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if (!trigger_data)
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goto out;
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enable_data = kzalloc(sizeof(*enable_data), GFP_KERNEL);
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if (!enable_data) {
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kfree(trigger_data);
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goto out;
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}
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trigger_data->count = -1;
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trigger_data->ops = trigger_ops;
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trigger_data->cmd_ops = cmd_ops;
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INIT_LIST_HEAD(&trigger_data->list);
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RCU_INIT_POINTER(trigger_data->filter, NULL);
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enable_data->enable = enable;
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enable_data->file = event_enable_file;
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trigger_data->private_data = enable_data;
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if (glob[0] == '!') {
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cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
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kfree(trigger_data);
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kfree(enable_data);
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ret = 0;
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goto out;
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}
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if (trigger) {
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number = strsep(&trigger, ":");
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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, &trigger_data->count);
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if (ret)
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goto out_free;
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}
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if (!param) /* if param is non-empty, it's supposed to be a filter */
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goto out_reg;
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if (!cmd_ops->set_filter)
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goto out_reg;
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ret = cmd_ops->set_filter(param, trigger_data, file);
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if (ret < 0)
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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(event_enable_file->event_call->mod);
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if (!ret) {
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ret = -EBUSY;
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goto out_free;
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}
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ret = trace_event_enable_disable(event_enable_file, 1, 1);
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if (ret < 0)
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goto out_put;
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ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
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/*
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* The above returns on success the # of functions enabled,
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* but if it didn't find any functions it returns zero.
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* Consider no functions a failure too.
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*/
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if (!ret) {
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ret = -ENOENT;
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goto out_disable;
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} else if (ret < 0)
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goto out_disable;
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/* Just return zero, not the number of enabled functions */
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ret = 0;
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out:
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return ret;
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out_disable:
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trace_event_enable_disable(event_enable_file, 0, 1);
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out_put:
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module_put(event_enable_file->event_call->mod);
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out_free:
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kfree(trigger_data);
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kfree(enable_data);
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goto out;
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}
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static int event_enable_register_trigger(char *glob,
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struct event_trigger_ops *ops,
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struct event_trigger_data *data,
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struct ftrace_event_file *file)
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{
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struct enable_trigger_data *enable_data = data->private_data;
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struct enable_trigger_data *test_enable_data;
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struct event_trigger_data *test;
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int ret = 0;
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list_for_each_entry_rcu(test, &file->triggers, list) {
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test_enable_data = test->private_data;
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if (test_enable_data &&
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(test_enable_data->file == enable_data->file)) {
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ret = -EEXIST;
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goto out;
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}
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}
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if (data->ops->init) {
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ret = data->ops->init(data->ops, data);
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if (ret < 0)
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goto out;
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}
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list_add_rcu(&data->list, &file->triggers);
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ret++;
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if (trace_event_trigger_enable_disable(file, 1) < 0) {
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list_del_rcu(&data->list);
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ret--;
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}
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out:
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return ret;
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}
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static void event_enable_unregister_trigger(char *glob,
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struct event_trigger_ops *ops,
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struct event_trigger_data *test,
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struct ftrace_event_file *file)
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{
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struct enable_trigger_data *test_enable_data = test->private_data;
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struct enable_trigger_data *enable_data;
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struct event_trigger_data *data;
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bool unregistered = false;
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list_for_each_entry_rcu(data, &file->triggers, list) {
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enable_data = data->private_data;
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if (enable_data &&
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(enable_data->file == test_enable_data->file)) {
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unregistered = true;
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list_del_rcu(&data->list);
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trace_event_trigger_enable_disable(file, 0);
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break;
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}
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}
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if (unregistered && data->ops->free)
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data->ops->free(data->ops, data);
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}
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static struct event_trigger_ops *
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event_enable_get_trigger_ops(char *cmd, char *param)
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{
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struct event_trigger_ops *ops;
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bool enable;
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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_trigger_ops :
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&event_enable_trigger_ops;
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else
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ops = param ? &event_disable_count_trigger_ops :
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&event_disable_trigger_ops;
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return ops;
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}
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static struct event_command trigger_enable_cmd = {
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.name = ENABLE_EVENT_STR,
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.trigger_type = ETT_EVENT_ENABLE,
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.func = event_enable_trigger_func,
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.reg = event_enable_register_trigger,
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.unreg = event_enable_unregister_trigger,
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.get_trigger_ops = event_enable_get_trigger_ops,
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};
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static struct event_command trigger_disable_cmd = {
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.name = DISABLE_EVENT_STR,
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.trigger_type = ETT_EVENT_ENABLE,
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.func = event_enable_trigger_func,
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.reg = event_enable_register_trigger,
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.unreg = event_enable_unregister_trigger,
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.get_trigger_ops = event_enable_get_trigger_ops,
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};
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static __init void unregister_trigger_enable_disable_cmds(void)
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{
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unregister_event_command(&trigger_enable_cmd);
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unregister_event_command(&trigger_disable_cmd);
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}
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static __init int register_trigger_enable_disable_cmds(void)
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{
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int ret;
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ret = register_event_command(&trigger_enable_cmd);
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if (WARN_ON(ret < 0))
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return ret;
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ret = register_event_command(&trigger_disable_cmd);
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if (WARN_ON(ret < 0))
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unregister_trigger_enable_disable_cmds();
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return ret;
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}
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static __init int register_trigger_traceon_traceoff_cmds(void)
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{
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int ret;
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@ -883,6 +1241,7 @@ __init int register_trigger_cmds(void)
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register_trigger_traceon_traceoff_cmds();
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register_trigger_snapshot_cmd();
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register_trigger_stacktrace_cmd();
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register_trigger_enable_disable_cmds();
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return 0;
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}
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