[for-next][PATCH 05/10] tracing: Add enable_event and disable_event event trigger commands

Steven Rostedt
2013-12-23T21:41:28Z

[-- Attachment #1: 0005-tracing-Add-enable_event-and-disable_event-event-tri.patch --]
[-- Type: text/plain, Size: 13076 bytes --]

From: Tom Zanussi <tom.zanussi@linux.intel.com>

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 | 1 +
kernel/trace/trace.h | 4 +
kernel/trace/trace_events.c | 2 +-
kernel/trace/trace_events_trigger.c | 359 ++++++++++++++++++++++++++++++++++++
4 files changed, 365 insertions(+), 1 deletion(-)

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 65caee4..2f73c398 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -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);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 50723e5..ccbd810 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -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);
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 442775c..9a974bd 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -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;
diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index a3bd1da..45e48b1 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -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;
}
--
1.8.4.3