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tracing: Add :mod: command to enabled module events

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Add a :mod: command to enable only events from a given module from the
set_events file.

  echo '*:mod:<module>' > set_events

Or

  echo ':mod:<module>' > set_events

Will enable all events for that module. Specific events can also be
enabled via:

  echo '<event>:mod:<module>' > set_events

Or

  echo '<system>:<event>:mod:<module>' > set_events

Or

  echo '*:<event>:mod:<module>' > set_events

The ":mod:" keyword is consistent with the function tracing filter to
enable functions from a given module.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/20250116143533.214496360@goodmis.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt 2025-01-16 09:33:35 -05:00 • committed by Steven Rostedt (Google)
parent 80c3e28528
commit 4c86bc531e
3 changed files with 70 additions and 13 deletions
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22
Documentation/trace/events.rst
View file

@ -55,6 +55,28 @@ command::
# echo 'irq:*' > /sys/kernel/tracing/set_event
The set_event file may also be used to enable events associated to only
a specific module::
# echo ':mod:<module>' > /sys/kernel/tracing/set_event
Will enable all events in the module ``<module>``.
The text before ``:mod:`` will be parsed to specify specific events that the
module creates::
# echo '<match>:mod:<module>' > /sys/kernel/tracing/set_event
The above will enable any system or event that ``<match>`` matches. If
``<match>`` is ``"*"`` then it will match all events.
To enable only a specific event within a system::
# echo '<system>:<event>:mod:<module>' > /sys/kernel/tracing/set_event
If ``<event>`` is ``"*"`` then it will match all events within the system
for a given module.
2.2 Via the 'enable' toggle
---------------------------

2
kernel/trace/trace.c
View file

@ -5514,6 +5514,8 @@ static const char readme_msg[] =
"\t efield: For event probes ('e' types), the field is on of the fields\n"
"\t of the <attached-group>/<attached-event>.\n"
#endif
" set_event\t\t- Enables events by name written into it\n"
"\t\t\t Can enable module events via: :mod:<module>\n"
" events/\t\t- Directory containing all trace event subsystems:\n"
" enable\t\t- Write 0/1 to enable/disable tracing of all events\n"
" events/<system>/\t- Directory containing all trace events for <system>:\n"

59
kernel/trace/trace_events.c
View file

@ -1153,17 +1153,36 @@ static void remove_event_file_dir(struct trace_event_file *file)
*/
static int
__ftrace_set_clr_event_nolock(struct trace_array *tr, const char *match,
const char *sub, const char *event, int set)
const char *sub, const char *event, int set,
const char *mod)
{
struct trace_event_file *file;
struct trace_event_call *call;
char *module __free(kfree) = NULL;
const char *name;
int ret = -EINVAL;
int eret = 0;
if (mod) {
char *p;
module = kstrdup(mod, GFP_KERNEL);
if (!module)
return -ENOMEM;
/* Replace all '-' with '_' as that's what modules do */
for (p = strchr(module, '-'); p; p = strchr(p + 1, '-'))
*p = '_';
}
list_for_each_entry(file, &tr->events, list) {
call = file->event_call;
/* If a module is specified, skip events that are not that module */
if (module && (!call->module || strcmp(module_name(call->module), module)))
continue;
name = trace_event_name(call);
if (!name || !call->class || !call->class->reg)
@ -1200,12 +1219,13 @@ __ftrace_set_clr_event_nolock(struct trace_array *tr, const char *match,
}
static int __ftrace_set_clr_event(struct trace_array *tr, const char *match,
const char *sub, const char *event, int set)
const char *sub, const char *event, int set,
const char *mod)
{
int ret;
mutex_lock(&event_mutex);
ret = __ftrace_set_clr_event_nolock(tr, match, sub, event, set);
ret = __ftrace_set_clr_event_nolock(tr, match, sub, event, set, mod);
mutex_unlock(&event_mutex);
return ret;
@ -1213,11 +1233,20 @@ static int __ftrace_set_clr_event(struct trace_array *tr, const char *match,
int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set)
{
char *event = NULL, *sub = NULL, *match;
char *event = NULL, *sub = NULL, *match, *mod;
int ret;
if (!tr)
return -ENOENT;
/* Modules events can be appened with :mod:<module> */
mod = strstr(buf, ":mod:");
if (mod) {
*mod = '\0';
/* move to the module name */
mod += 5;
}
/*
* The buf format can be <subsystem>:<event-name>
* *:<event-name> means any event by that name.
@ -1240,9 +1269,13 @@ int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set)
sub = NULL;
if (!strlen(event) || strcmp(event, "*") == 0)
event = NULL;
} else if (mod) {
/* Allow wildcard for no length or star */
if (!strlen(match) || strcmp(match, "*") == 0)
match = NULL;
}
ret = __ftrace_set_clr_event(tr, match, sub, event, set);
ret = __ftrace_set_clr_event(tr, match, sub, event, set, mod);
/* Put back the colon to allow this to be called again */
if (buf)
@ -1270,7 +1303,7 @@ int trace_set_clr_event(const char *system, const char *event, int set)
if (!tr)
return -ENODEV;
return __ftrace_set_clr_event(tr, NULL, system, event, set);
return __ftrace_set_clr_event(tr, NULL, system, event, set, NULL);
}
EXPORT_SYMBOL_GPL(trace_set_clr_event);
@ -1296,7 +1329,7 @@ int trace_array_set_clr_event(struct trace_array *tr, const char *system,
return -ENOENT;
set = (enable == true) ? 1 : 0;
return __ftrace_set_clr_event(tr, NULL, system, event, set);
return __ftrace_set_clr_event(tr, NULL, system, event, set, NULL);
}
EXPORT_SYMBOL_GPL(trace_array_set_clr_event);
@ -1646,7 +1679,7 @@ system_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
if (system)
name = system->name;
ret = __ftrace_set_clr_event(dir->tr, NULL, name, NULL, val);
ret = __ftrace_set_clr_event(dir->tr, NULL, name, NULL, val, NULL);
if (ret)
goto out;
@ -4094,7 +4127,7 @@ int event_trace_del_tracer(struct trace_array *tr)
__ftrace_clear_event_pids(tr, TRACE_PIDS | TRACE_NO_PIDS);
/* Disable any running events */
__ftrace_set_clr_event_nolock(tr, NULL, NULL, NULL, 0);
__ftrace_set_clr_event_nolock(tr, NULL, NULL, NULL, 0, NULL);
/* Make sure no more events are being executed */
tracepoint_synchronize_unregister();
@ -4378,7 +4411,7 @@ static __init void event_trace_self_tests(void)
pr_info("Testing event system %s: ", system->name);
ret = __ftrace_set_clr_event(tr, NULL, system->name, NULL, 1);
ret = __ftrace_set_clr_event(tr, NULL, system->name, NULL, 1, NULL);
if (WARN_ON_ONCE(ret)) {
pr_warn("error enabling system %s\n",
system->name);
@ -4387,7 +4420,7 @@ static __init void event_trace_self_tests(void)
event_test_stuff();
ret = __ftrace_set_clr_event(tr, NULL, system->name, NULL, 0);
ret = __ftrace_set_clr_event(tr, NULL, system->name, NULL, 0, NULL);
if (WARN_ON_ONCE(ret)) {
pr_warn("error disabling system %s\n",
system->name);
@ -4402,7 +4435,7 @@ static __init void event_trace_self_tests(void)
pr_info("Running tests on all trace events:\n");
pr_info("Testing all events: ");
ret = __ftrace_set_clr_event(tr, NULL, NULL, NULL, 1);
ret = __ftrace_set_clr_event(tr, NULL, NULL, NULL, 1, NULL);
if (WARN_ON_ONCE(ret)) {
pr_warn("error enabling all events\n");
return;
@ -4411,7 +4444,7 @@ static __init void event_trace_self_tests(void)
event_test_stuff();
/* reset sysname */
ret = __ftrace_set_clr_event(tr, NULL, NULL, NULL, 0);
ret = __ftrace_set_clr_event(tr, NULL, NULL, NULL, 0, NULL);
if (WARN_ON_ONCE(ret)) {
pr_warn("error disabling all events\n");
return;