Add 'traceon' and 'traceoff' ftrace_func_command commands. traceon
and traceoff event triggers are added by the user via these commands
in a similar way and using practically the same syntax as the
analagous 'traceon' and 'traceoff' ftrace function commands, but
instead of writing to the set_ftrace_filter file, the traceon and
traceoff triggers are written to the per-event 'trigger' files:
echo 'traceon' > .../tracing/events/somesys/someevent/trigger
echo 'traceoff' > .../tracing/events/somesys/someevent/trigger
The above command will turn tracing on or off whenever someevent is
hit.
This also adds a 'count' version that limits the number of times the
command will be invoked:
echo 'traceon:N' > .../tracing/events/somesys/someevent/trigger
echo 'traceoff:N' > .../tracing/events/somesys/someevent/trigger
Where N is the number of times the command will be invoked.
The above commands will will turn tracing on or off whenever someevent
is hit, but only N times.
The event_trigger_init() and event_trigger_free() are meant to be
common implementations of the event_trigger_ops init() and free() ops.
Most trigger_ops implementations will use these, but some will
override and possibly reuse them.
Signed-off-by: Tom Zanussi <tom.zanu...@linux.intel.com>
---
include/linux/ftrace_event.h | 1 +
kernel/trace/trace_events_trigger.c | 313 ++++++++++++++++++++++++++++++++++++
2 files changed, 314 insertions(+)
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 6cd5bbc..c794686 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -316,6 +316,7 @@ struct ftrace_event_file {
enum trigger_mode {
TM_NONE = (0),
+ TM_TRACE_ONOFF = (1 << 0),
};
extern void destroy_preds(struct ftrace_event_call *call);
diff --git a/kernel/trace/trace_events_trigger.c
b/kernel/trace/trace_events_trigger.c
index 1f0565c..f2b97b6 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -355,7 +355,320 @@ static void unregister_trigger(char *glob, struct
event_trigger_ops *ops,
data->ops->free(data->ops, (void **)&data);
}
+int
+event_trigger_print(const char *name, struct seq_file *m,
+ void *data, char *filter_str)
+{
+ long count = (long)data;
+
+ seq_printf(m, "%s", name);
+
+ if (count == -1)
+ seq_puts(m, ":unlimited");
+ else
+ seq_printf(m, ":count=%ld", count);
+
+ if (filter_str)
+ seq_printf(m, " if %s\n", filter_str);
+ else
+ seq_puts(m, "\n");
+
+ return 0;
+}
+
+static int
+event_trigger_init(struct event_trigger_ops *ops, void **_data)
+{
+ struct event_trigger_data **p = (struct event_trigger_data **)_data;
+ struct event_trigger_data *data = *p;
+
+ data->ref++;
+ return 0;
+}
+
+static void
+event_trigger_free(struct event_trigger_ops *ops, void **_data)
+{
+ struct event_trigger_data **p = (struct event_trigger_data **)_data;
+ struct event_trigger_data *data = *p;
+
+ if (WARN_ON_ONCE(data->ref <= 0))
+ return;
+
+ data->ref--;
+ if (!data->ref)
+ kfree(data);
+}
+
+static int
+event_trigger_callback(struct event_command *cmd_ops, void *cmd_data,
+ char *glob, char *cmd, char *param, int enabled)
+{
+ struct event_trigger_ops *trigger_ops;
+ struct event_trigger_data *trigger_data;
+ char *trigger = NULL;
+ char *number;
+ int ret;
+
+ if (!enabled)
+ return -EINVAL;
+
+ /* separate the trigger from the filter (t:n [if filter]) */
+ if (param && isdigit(param[0]))
+ trigger = strsep(¶m, " \t");
+
+ mutex_lock(&event_mutex);
+
+ trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
+
+ ret = -ENOMEM;
+ trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
+ if (!trigger_data)
+ goto out;
+
+ trigger_data->count = -1;
+ trigger_data->ops = trigger_ops;
+ trigger_data->mode = cmd_ops->trigger_mode;
+ INIT_LIST_HEAD(&trigger_data->list);
+
+ if (glob[0] == '!') {
+ cmd_ops->unreg(glob+1, trigger_ops, trigger_data, cmd_data);
+ kfree(trigger_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, cmd_data);
+ if (ret < 0)
+ goto out_free;
+
+ out_reg:
+ ret = cmd_ops->reg(glob, trigger_ops, trigger_data, cmd_data);
+ /*
+ * 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_free;
+ } else if (ret < 0)
+ goto out_free;
+ ret = 0;
+ out:
+ mutex_unlock(&event_mutex);
+ return ret;
+
+ out_free:
+ kfree(trigger_data);
+ goto out;
+}
+
+static void
+traceon_trigger(void **_data)
+{
+ struct event_trigger_data **p = (struct event_trigger_data **)_data;
+ struct event_trigger_data *data = *p;
+
+ if (!data)
+ return;
+
+ if (tracing_is_on())
+ return;
+
+ tracing_on();
+}
+
+static void
+traceon_count_trigger(void **_data)
+{
+ struct event_trigger_data **p = (struct event_trigger_data **)_data;
+ struct event_trigger_data *data = *p;
+
+ if (!data)
+ return;
+
+ if (!data->count)
+ return;
+
+ if (data->count != -1)
+ (data->count)--;
+
+ traceon_trigger(_data);
+}
+
+static void
+traceoff_trigger(void **_data)
+{
+ struct event_trigger_data **p = (struct event_trigger_data **)_data;
+ struct event_trigger_data *data = *p;
+
+ if (!data)
+ return;
+
+ if (!tracing_is_on())
+ return;
+
+ tracing_off();
+}
+
+static void
+traceoff_count_trigger(void **_data)
+{
+ struct event_trigger_data **p = (struct event_trigger_data **)_data;
+ struct event_trigger_data *data = *p;
+
+ if (!data)
+ return;
+
+ if (!data->count)
+ return;
+
+ if (data->count != -1)
+ (data->count)--;
+
+ traceoff_trigger(_data);
+}
+
+static int
+traceon_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
+ void *_data)
+{
+ struct event_trigger_data *data = _data;
+
+ return event_trigger_print("traceon", m, (void *)data->count,
+ data->filter_str);
+}
+
+static int
+traceoff_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
+ void *_data)
+{
+ struct event_trigger_data *data = _data;
+
+ return event_trigger_print("traceoff", m, (void *)data->count,
+ data->filter_str);
+}
+
+static struct event_trigger_ops traceon_trigger_ops = {
+ .func = traceon_trigger,
+ .print = traceon_trigger_print,
+ .init = event_trigger_init,
+ .free = event_trigger_free,
+};
+
+static struct event_trigger_ops traceon_count_trigger_ops = {
+ .func = traceon_count_trigger,
+ .print = traceon_trigger_print,
+ .init = event_trigger_init,
+ .free = event_trigger_free,
+};
+
+static struct event_trigger_ops traceoff_trigger_ops = {
+ .func = traceoff_trigger,
+ .print = traceoff_trigger_print,
+ .init = event_trigger_init,
+ .free = event_trigger_free,
+};
+
+static struct event_trigger_ops traceoff_count_trigger_ops = {
+ .func = traceoff_count_trigger,
+ .print = traceoff_trigger_print,
+ .init = event_trigger_init,
+ .free = event_trigger_free,
+};
+
+static struct event_trigger_ops *
+onoff_get_trigger_ops(char *cmd, char *param)
+{
+ struct event_trigger_ops *ops;
+
+ /* we register both traceon and traceoff to this callback */
+ if (strcmp(cmd, "traceon") == 0)
+ ops = param ? &traceon_count_trigger_ops :
+ &traceon_trigger_ops;
+ else
+ ops = param ? &traceoff_count_trigger_ops :
+ &traceoff_trigger_ops;
+
+ return ops;
+}
+
+static struct event_command trigger_traceon_cmd = {
+ .name = "traceon",
+ .trigger_mode = TM_TRACE_ONOFF,
+ .func = event_trigger_callback,
+ .reg = register_trigger,
+ .unreg = unregister_trigger,
+ .get_trigger_ops = onoff_get_trigger_ops,
+};
+
+static struct event_command trigger_traceoff_cmd = {
+ .name = "traceoff",
+ .trigger_mode = TM_TRACE_ONOFF,
+ .func = event_trigger_callback,
+ .reg = register_trigger,
+ .unreg = unregister_trigger,
+ .get_trigger_ops = onoff_get_trigger_ops,
+};
+
+static __init void unregister_trigger_traceon_traceoff_cmds(void)
+{
+ unregister_event_command(&trigger_traceon_cmd,
+ &trigger_commands,
+ &trigger_cmd_mutex);
+ unregister_event_command(&trigger_traceoff_cmd,
+ &trigger_commands,
+ &trigger_cmd_mutex);
+}
+
+static __init int register_trigger_traceon_traceoff_cmds(void)
+{
+ int ret;
+
+ ret = register_event_command(&trigger_traceon_cmd, &trigger_commands,
+ &trigger_cmd_mutex);
+ if (WARN_ON(ret < 0))
+ return ret;
+ ret = register_event_command(&trigger_traceoff_cmd, &trigger_commands,
+ &trigger_cmd_mutex);
+ if (WARN_ON(ret < 0))
+ unregister_trigger_traceon_traceoff_cmds();
+
+ return ret;
+}
+
__init int register_trigger_cmds(void)
{
+ int ret;
+
+ ret = register_trigger_traceon_traceoff_cmds();
+ if (ret) {
+ unregister_trigger_traceon_traceoff_cmds();
+ return ret;
+ }
+
return 0;
}
--
1.7.11.4
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