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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:
Tom Zanussi 2013-10-24 08:59:28 -05:00 committed by Steven Rostedt
parent f21ecbb35f
commit 7862ad1846
4 changed files with 365 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/ftrace_event.h
View File

@ -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);

4
kernel/trace/trace.h
View File

@ -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);

2
kernel/trace/trace_events.c
View File

@ -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;

359
kernel/trace/trace_events_trigger.c
View File

@ -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;
}