[PATCH 0/3] tracing: Add ':mod:' command to set_event to enable events in modules

[PATCH 0/3] tracing: Add ':mod:' command to set_event to enable events in modules

[Steven Rostedt]

I was asked if there was a way to enable events for a module on boot
up. Unfortunately there currently isn't a way to do so. I decided to
added the ":mod:" feature that set_ftrace_filter has to the set_event
file as well as to the kernel command line (which uses the same code
as what the set_event file takes).

Now you can enable events for a given module without having to know
what events that module has.

 echo ':mod:<module' > set_event

You can enable some events or event systems for a module too:

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

Where either <system> or <event> can be missing or "*".

For the following:

 echo '<match>:mod:<module>' > set_event

It will enable any system or event that has the name <match>.

If the module is not loaded, then the string is saved, and when the
module is loaded, it will be executed on that module before the module
executes. This means any module event that is called in its init
functions will also be traced.

This works on the kernel command line as well:

  trace_event=:mod:<module>

Will enable all the events for <module> when it is loaded.

I also added a thorough test to test this feature, although it doest
obviously test the kernel command line.

This is based on top of

  git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
  trace/for-next

Steven Rostedt (3):
      tracing: Add ':mod:' command to enabled module events
      tracing: Cache ":mod:" events for modules not loaded yet
      selftests/ftrace: Add test that tests event :mod: commands

----
 Documentation/admin-guide/kernel-parameters.txt    |   8 +
 Documentation/trace/events.rst                     |  24 ++
 kernel/trace/ftrace.c                              |  17 --
 kernel/trace/trace.c                               |  28 ++
 kernel/trace/trace.h                               |  12 +
 kernel/trace/trace_events.c                        | 300 +++++++++++++++++++--
 .../selftests/ftrace/test.d/event/event-mod.tc     | 192 +++++++++++++
 7 files changed, 540 insertions(+), 41 deletions(-)
 create mode 100644 tools/testing/selftests/ftrace/test.d/event/event-mod.tc

[PATCH 1/3] tracing: Add :mod: command to enabled module events

[Steven Rostedt]

From: Steven Rostedt <rostedt@goodmis.org>

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.

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 Documentation/trace/events.rst | 22 +++++++++++++
 kernel/trace/trace.c           |  2 ++
 kernel/trace/trace_events.c    | 59 ++++++++++++++++++++++++++--------
 3 files changed, 70 insertions(+), 13 deletions(-)

diff --git a/Documentation/trace/events.rst b/Documentation/trace/events.rst
index 759907c20e75..3db57516eb86 100644
--- a/Documentation/trace/events.rst
+++ b/Documentation/trace/events.rst
@@ -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
 ---------------------------
 
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 5aeb898054e7..cb85ee4a8807 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -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"
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 2b9222e7bd5a..5c7d0e07618d 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -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;
-- 
2.45.2

[PATCH 2/3] tracing: Cache ":mod:" events for modules not loaded yet

[Steven Rostedt]

From: Steven Rostedt <rostedt@goodmis.org>

When the :mod: command is written into /sys/kernel/tracing/set_event (or
that file within an instance), if the module specified after the ":mod:"
is not yet loaded, it will store that string internally. When the module
is loaded, it will enable the events as if the module was loaded when the
string was written into the set_event file.

This can also be useful to enable events that are in the init section of
the module, as the events are enabled before the init section is executed.

This also works on the kernel command line:

 trace_event=:mod:<module>

Will enable the events for <module> when it is loaded.

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 .../admin-guide/kernel-parameters.txt         |   8 +
 Documentation/trace/events.rst                |   4 +-
 kernel/trace/ftrace.c                         |  17 --
 kernel/trace/trace.c                          |  26 ++
 kernel/trace/trace.h                          |  12 +
 kernel/trace/trace_events.c                   | 241 +++++++++++++++++-
 6 files changed, 279 insertions(+), 29 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 3872bc6ec49d..4f563cb0ca0f 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6858,6 +6858,14 @@
 			comma-separated list of trace events to enable. See
 			also Documentation/trace/events.rst
 
+			To enable modules, use :mod: keyword:
+
+			trace_event=:mod:<module>
+
+			The value before :mod: will only enable specific events
+			that are part of the module. See the above mentioned
+			document for more information.
+
 	trace_instance=[instance-info]
 			[FTRACE] Create a ring buffer instance early in boot up.
 			This will be listed in:
diff --git a/Documentation/trace/events.rst b/Documentation/trace/events.rst
index 3db57516eb86..2d88a2acacc0 100644
--- a/Documentation/trace/events.rst
+++ b/Documentation/trace/events.rst
@@ -60,7 +60,9 @@ a specific module::
 
 	# echo ':mod:<module>' > /sys/kernel/tracing/set_event
 
-Will enable all events in the module ``<module>``.
+Will enable all events in the module ``<module>``.  If the module is not yet
+loaded, the string will be saved and when a module is that matches ``<module>``
+is loaded, then it will apply the enabling of events then.
 
 The text before ``:mod:`` will be parsed to specify specific events that the
 module creates::
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 9b17efb1a87d..cafcfc97ff2a 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -4930,23 +4930,6 @@ static int ftrace_hash_move_and_update_ops(struct ftrace_ops *ops,
 	return __ftrace_hash_move_and_update_ops(ops, orig_hash, hash, enable);
 }
 
-static bool module_exists(const char *module)
-{
-	/* All modules have the symbol __this_module */
-	static const char this_mod[] = "__this_module";
-	char modname[MAX_PARAM_PREFIX_LEN + sizeof(this_mod) + 2];
-	unsigned long val;
-	int n;
-
-	n = snprintf(modname, sizeof(modname), "%s:%s", module, this_mod);
-
-	if (n > sizeof(modname) - 1)
-		return false;
-
-	val = module_kallsyms_lookup_name(modname);
-	return val != 0;
-}
-
 static int cache_mod(struct trace_array *tr,
 		     const char *func, char *module, int enable)
 {
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index cb85ee4a8807..87402b6e8c58 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -9407,6 +9407,10 @@ trace_array_create_systems(const char *name, const char *systems,
 	INIT_LIST_HEAD(&tr->hist_vars);
 	INIT_LIST_HEAD(&tr->err_log);
 
+#ifdef CONFIG_MODULES
+	INIT_LIST_HEAD(&tr->mod_events);
+#endif
+
 	if (allocate_trace_buffers(tr, trace_buf_size) < 0)
 		goto out_free_tr;
 
@@ -9823,6 +9827,24 @@ late_initcall_sync(trace_eval_sync);
 
 
 #ifdef CONFIG_MODULES
+
+bool module_exists(const char *module)
+{
+	/* All modules have the symbol __this_module */
+	static const char this_mod[] = "__this_module";
+	char modname[MAX_PARAM_PREFIX_LEN + sizeof(this_mod) + 2];
+	unsigned long val;
+	int n;
+
+	n = snprintf(modname, sizeof(modname), "%s:%s", module, this_mod);
+
+	if (n > sizeof(modname) - 1)
+		return false;
+
+	val = module_kallsyms_lookup_name(modname);
+	return val != 0;
+}
+
 static void trace_module_add_evals(struct module *mod)
 {
 	if (!mod->num_trace_evals)
@@ -10535,6 +10557,10 @@ __init static int tracer_alloc_buffers(void)
 #endif
 	ftrace_init_global_array_ops(&global_trace);
 
+#ifdef CONFIG_MODULES
+	INIT_LIST_HEAD(&global_trace.mod_events);
+#endif
+
 	init_trace_flags_index(&global_trace);
 
 	register_tracer(&nop_trace);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 9691b47b5f3d..05ea0ebf5eba 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -400,6 +400,9 @@ struct trace_array {
 	cpumask_var_t		pipe_cpumask;
 	int			ref;
 	int			trace_ref;
+#ifdef CONFIG_MODULES
+	struct list_head	mod_events;
+#endif
 #ifdef CONFIG_FUNCTION_TRACER
 	struct ftrace_ops	*ops;
 	struct trace_pid_list	__rcu *function_pids;
@@ -434,6 +437,15 @@ enum {
 	TRACE_ARRAY_FL_BOOT	= BIT(1),
 };
 
+#ifdef CONFIG_MODULES
+bool module_exists(const char *module);
+#else
+static inline bool module_exists(const char *module)
+{
+	return false;
+}
+#endif
+
 extern struct list_head ftrace_trace_arrays;
 
 extern struct mutex trace_types_lock;
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 5c7d0e07618d..f762e554fad4 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -857,6 +857,120 @@ static int ftrace_event_enable_disable(struct trace_event_file *file,
 	return __ftrace_event_enable_disable(file, enable, 0);
 }
 
+#if CONFIG_MODULES
+struct event_mod_load {
+	struct list_head	list;
+	char			*module;
+	char			*match;
+	char			*system;
+	char			*event;
+};
+
+static void free_event_mod(struct event_mod_load *event_mod)
+{
+	list_del(&event_mod->list);
+	kfree(event_mod->module);
+	kfree(event_mod->match);
+	kfree(event_mod->system);
+	kfree(event_mod->event);
+	kfree(event_mod);
+}
+
+static void clear_mod_events(struct trace_array *tr)
+{
+	struct event_mod_load *event_mod, *n;
+
+	list_for_each_entry_safe(event_mod, n, &tr->mod_events, list) {
+		free_event_mod(event_mod);
+	}
+}
+
+static int remove_cache_mod(struct trace_array *tr, const char *mod,
+			    const char *match, const char *system, const char *event)
+{
+	struct event_mod_load *event_mod, *n;
+	int ret = -EINVAL;
+
+	list_for_each_entry_safe(event_mod, n, &tr->mod_events, list) {
+		if (strcmp(event_mod->module, mod) != 0)
+			continue;
+
+		if (match && strcmp(event_mod->match, match) != 0)
+			continue;
+
+		if (system &&
+		    (!event_mod->system || strcmp(event_mod->system, system) != 0))
+			continue;
+
+		if (event &&
+		    (!event_mod->event || strcmp(event_mod->event, event) != 0))
+			continue;
+
+		free_event_mod(event_mod);
+		ret = 0;
+	}
+
+	return ret;
+}
+
+static int cache_mod(struct trace_array *tr, const char *mod, int set,
+		     const char *match, const char *system, const char *event)
+{
+	struct event_mod_load *event_mod;
+
+	/* If the module exists, then this just failed to find an event */
+	if (module_exists(mod))
+		return -EINVAL;
+
+	/* See if this is to remove a cached filter */
+	if (!set)
+		return remove_cache_mod(tr, mod, match, system, event);
+
+	event_mod = kzalloc(sizeof(*event_mod), GFP_KERNEL);
+	if (!event_mod)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&event_mod->list);
+	event_mod->module = kstrdup(mod, GFP_KERNEL);
+	if (!event_mod->module)
+		goto out_free;
+
+	if (match) {
+		event_mod->match = kstrdup(match, GFP_KERNEL);
+		if (!event_mod->match)
+			goto out_free;
+	}
+
+	if (system) {
+		event_mod->system = kstrdup(system, GFP_KERNEL);
+		if (!event_mod->system)
+			goto out_free;
+	}
+
+	if (event) {
+		event_mod->event = kstrdup(event, GFP_KERNEL);
+		if (!event_mod->event)
+			goto out_free;
+	}
+
+	list_add(&event_mod->list, &tr->mod_events);
+
+	return 0;
+
+ out_free:
+	free_event_mod(event_mod);
+
+	return -ENOMEM;
+}
+#else /* CONFIG_MODULES */
+static inline void clear_mod_events(struct trace_array *tr) { }
+static int cache_mod(struct trace_array *tr, const char *mod, int set,
+		     const char *match, const char *system, const char *event)
+{
+	return -EINVAL;
+}
+#endif
+
 static void ftrace_clear_events(struct trace_array *tr)
 {
 	struct trace_event_file *file;
@@ -865,6 +979,7 @@ static void ftrace_clear_events(struct trace_array *tr)
 	list_for_each_entry(file, &tr->events, list) {
 		ftrace_event_enable_disable(file, 0);
 	}
+	clear_mod_events(tr);
 	mutex_unlock(&event_mutex);
 }
 
@@ -1215,6 +1330,13 @@ __ftrace_set_clr_event_nolock(struct trace_array *tr, const char *match,
 		ret = eret;
 	}
 
+	/*
+	 * If this is a module setting and nothing was found,
+	 * check if the module was loaded. If it wasn't cache it.
+	 */
+	if (module && ret == -EINVAL && !eret)
+		ret = cache_mod(tr, module, set, match, sub, event);
+
 	return ret;
 }
 
@@ -1416,37 +1538,71 @@ static void *t_start(struct seq_file *m, loff_t *pos)
 	return file;
 }
 
+enum set_event_iter_type {
+	SET_EVENT_FILE,
+	SET_EVENT_MOD,
+};
+
+struct set_event_iter {
+	enum set_event_iter_type	type;
+	union {
+		struct trace_event_file	*file;
+		struct event_mod_load	*event_mod;
+	};
+};
+
 static void *
 s_next(struct seq_file *m, void *v, loff_t *pos)
 {
-	struct trace_event_file *file = v;
+	struct set_event_iter *iter = v;
+	struct trace_event_file *file;
 	struct trace_array *tr = m->private;
 
 	(*pos)++;
 
-	list_for_each_entry_continue(file, &tr->events, list) {
-		if (file->flags & EVENT_FILE_FL_ENABLED)
-			return file;
+	if (iter->type == SET_EVENT_FILE) {
+		file = iter->file;
+		list_for_each_entry_continue(file, &tr->events, list) {
+			if (file->flags & EVENT_FILE_FL_ENABLED) {
+				iter->file = file;
+				return iter;
+			}
+		}
+#ifdef CONFIG_MODULES
+		iter->type = SET_EVENT_MOD;
+		iter->event_mod = list_entry(&tr->mod_events, struct event_mod_load, list);
+#endif
 	}
 
+#ifdef CONFIG_MODULES
+	list_for_each_entry_continue(iter->event_mod, &tr->mod_events, list)
+		return iter;
+#endif
+
 	return NULL;
 }
 
 static void *s_start(struct seq_file *m, loff_t *pos)
 {
-	struct trace_event_file *file;
 	struct trace_array *tr = m->private;
+	struct set_event_iter *iter;
 	loff_t l;
 
+	iter = kzalloc(sizeof(iter), GFP_KERNEL);
+	if (!iter)
+		return NULL;
+
 	mutex_lock(&event_mutex);
 
-	file = list_entry(&tr->events, struct trace_event_file, list);
+	iter->type = SET_EVENT_FILE;
+	iter->file = list_entry(&tr->events, struct trace_event_file, list);
+
 	for (l = 0; l <= *pos; ) {
-		file = s_next(m, file, &l);
-		if (!file)
+		iter = s_next(m, iter, &l);
+		if (!iter)
 			break;
 	}
-	return file;
+	return iter;
 }
 
 static int t_show(struct seq_file *m, void *v)
@@ -1466,6 +1622,45 @@ static void t_stop(struct seq_file *m, void *p)
 	mutex_unlock(&event_mutex);
 }
 
+#ifdef CONFIG_MODULES
+static int s_show(struct seq_file *m, void *v)
+{
+	struct set_event_iter *iter = v;
+	const char *system;
+	const char *event;
+
+	if (iter->type == SET_EVENT_FILE)
+		return t_show(m, iter->file);
+
+	/* When match is set, system and event are not */
+	if (iter->event_mod->match) {
+		seq_printf(m, "%s:mod:%s", iter->event_mod->match,
+			   iter->event_mod->module);
+		return 0;
+	}
+
+	system = iter->event_mod->system ? : "*";
+	event = iter->event_mod->event ? : "*";
+
+	seq_printf(m, "%s:%s:mod:%s\n", system, event, iter->event_mod->module);
+
+	return 0;
+}
+#else /* CONFIG_MODULES */
+static int s_show(struct seq_file *m, void *v)
+{
+	struct set_event_iter *iter = v;
+
+	return t_show(m, iter->file);
+}
+#endif
+
+static void s_stop(struct seq_file *m, void *p)
+{
+	kfree(p);
+	t_stop(m, NULL);
+}
+
 static void *
 __next(struct seq_file *m, void *v, loff_t *pos, int type)
 {
@@ -2253,8 +2448,8 @@ static const struct seq_operations show_event_seq_ops = {
 static const struct seq_operations show_set_event_seq_ops = {
 	.start = s_start,
 	.next = s_next,
-	.show = t_show,
-	.stop = t_stop,
+	.show = s_show,
+	.stop = s_stop,
 };
 
 static const struct seq_operations show_set_pid_seq_ops = {
@@ -3385,6 +3580,28 @@ EXPORT_SYMBOL_GPL(trace_remove_event_call);
 	     event++)
 
 #ifdef CONFIG_MODULES
+static void update_cache(struct trace_array *tr, struct module *mod)
+{
+	struct event_mod_load *event_mod, *n;
+
+	list_for_each_entry_safe(event_mod, n, &tr->mod_events, list) {
+		if (strcmp(event_mod->module, mod->name) != 0)
+			continue;
+
+		__ftrace_set_clr_event_nolock(tr, event_mod->match,
+					      event_mod->system,
+					      event_mod->event, 1, mod->name);
+		free_event_mod(event_mod);
+	}
+}
+
+static void update_cache_events(struct module *mod)
+{
+	struct trace_array *tr;
+
+	list_for_each_entry(tr, &ftrace_trace_arrays, list)
+		update_cache(tr, mod);
+}
 
 static void trace_module_add_events(struct module *mod)
 {
@@ -3407,6 +3624,8 @@ static void trace_module_add_events(struct module *mod)
 		__register_event(*call, mod);
 		__add_event_to_tracers(*call);
 	}
+
+	update_cache_events(mod);
 }
 
 static void trace_module_remove_events(struct module *mod)
-- 
2.45.2

[PATCH 3/3] selftests/ftrace: Add test that tests event :mod: commands

[Steven Rostedt]

From: Steven Rostedt <rostedt@goodmis.org>

Now that here's a :mod: command that can be sent into set_event, add a
test that tests its use. Both setting events for a loaded module, as well
as caching what events to set for a module that is not loaded yet.

Cc: Shuah Khan <shuah@kernel.org>
Cc: linux-kselftest@vger.kernel.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 .../ftrace/test.d/event/event-mod.tc          | 192 ++++++++++++++++++
 1 file changed, 192 insertions(+)
 create mode 100644 tools/testing/selftests/ftrace/test.d/event/event-mod.tc

diff --git a/tools/testing/selftests/ftrace/test.d/event/event-mod.tc b/tools/testing/selftests/ftrace/test.d/event/event-mod.tc
new file mode 100644
index 000000000000..6f7601c4b54b
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/event/event-mod.tc
@@ -0,0 +1,192 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: event tracing - enable/disable with module event
+# requires: set_event "Can enable module events via: :mod:":README
+# flags: instance
+
+rmmod trace-events-sample ||:
+if ! modprobe trace-events-sample ; then
+  echo "No trace-events sample module - please make CONFIG_SAMPLE_TRACE_EVENTS=m"
+  exit_unresolved;
+fi
+trap "rmmod trace-events-sample" EXIT
+
+# Set events for the module
+echo ":mod:trace-events-sample" > set_event
+
+test_all_enabled() {
+
+	# Check if more than one is enabled
+	grep -q sample-trace:foo_bar set_event
+	grep -q sample-trace:foo_bar_with_cond set_event
+	grep -q sample-trace:foo_bar_with_fn set_event
+
+	# All of them should be enabled. Check via the enable file
+	val=`cat events/sample-trace/enable`
+	if [ $val -ne 1 ]; then
+		exit_fail
+	fi
+}
+
+clear_events() {
+	echo > set_event
+	val=`cat events/enable`
+	if [ "$val" != "0" ]; then
+		exit_fail
+	fi
+	count=`cat set_event | wc -l`
+	if [ $count -ne 0 ]; then
+		exit_fail
+	fi
+}
+
+test_all_enabled
+
+echo clear all events
+echo 0 > events/enable
+
+echo Confirm the events are disabled
+val=`cat events/sample-trace/enable`
+if [ $val -ne 0 ]; then
+	exit_fail
+fi
+
+echo And the set_event file is empty
+
+cnt=`wc -l set_event`
+if [ $cnt -ne 0 ]; then
+	exit_fail
+fi
+
+echo now enable all events
+echo 1 > events/enable
+
+echo Confirm the events are enabled again
+val=`cat events/sample-trace/enable`
+if [ $val -ne 1 ]; then
+	exit_fail
+fi
+
+echo disable just the module events
+echo '!:mod:trace-events-sample' >> set_event
+
+echo Should have mix of events enabled
+val=`cat events/enable`
+if [ "$val" != "X" ]; then
+	exit_fail
+fi
+
+echo Confirm the module events are disabled
+val=`cat events/sample-trace/enable`
+if [ $val -ne 0 ]; then
+	exit_fail
+fi
+
+echo 0 > events/enable
+
+echo now enable the system events
+echo 'sample-trace:mod:trace-events-sample' > set_event
+
+test_all_enabled
+
+echo clear all events
+echo 0 > events/enable
+
+echo Confirm the events are disabled
+val=`cat events/sample-trace/enable`
+if [ $val -ne 0 ]; then
+	exit_fail
+fi
+
+echo Test enabling foo_bar only
+echo 'foo_bar:mod:trace-events-sample' > set_event
+
+grep -q sample-trace:foo_bar set_event
+
+echo make sure nothing is found besides foo_bar
+if grep -q -v sample-trace:foo_bar set_event ; then
+	exit_fail
+fi
+
+echo Append another using the system and event name
+echo 'sample-trace:foo_bar_with_cond:mod:trace-events-sample' >> set_event
+
+grep -q sample-trace:foo_bar set_event
+grep -q sample-trace:foo_bar_with_cond set_event
+
+count=`cat set_event | wc -l`
+
+if [ $count -ne 2 ]; then
+	exit_fail
+fi
+
+clear_events
+
+rmmod trace-events-sample
+
+echo ':mod:trace-events-sample' > set_event
+
+echo make sure that the module shows up, and '-' is converted to '_'
+grep -q '\*:\*:mod:trace_events_sample' set_event
+
+modprobe trace-events-sample
+
+test_all_enabled
+
+clear_events
+
+rmmod trace-events-sample
+
+echo Enable just the system events
+echo 'sample-trace:mod:trace-events-sample' > set_event
+grep -q 'sample-trace:mod:trace_events_sample' set_event
+
+modprobe trace-events-sample
+
+test_all_enabled
+
+clear_events
+
+rmmod trace-events-sample
+
+echo Enable event with just event name
+echo 'foo_bar:mod:trace-events-sample' > set_event
+grep -q 'foo_bar:mod:trace_events_sample' set_event
+
+echo Enable another event with both system and event name
+echo 'sample-trace:foo_bar_with_cond:mod:trace-events-sample' >> set_event
+grep -q 'sample-trace:foo_bar_with_cond:mod:trace_events_sample' set_event
+echo Make sure the other event was still there
+grep -q 'foo_bar:mod:trace_events_sample' set_event
+
+modprobe trace-events-sample
+
+echo There should be no :mod: cached events
+if grep -q ':mod:' set_event; then
+	exit_fail
+fi
+
+echo two events should be enabled
+count=`cat set_event | wc -l`
+if [ $count -ne 2 ]; then
+	exit_fail
+fi
+
+echo only two events should be enabled
+val=`cat events/sample-trace/enable`
+if [ "$val" != "X" ]; then
+	exit_fail
+fi
+
+val=`cat events/sample-trace/foo_bar/enable`
+if [ "$val" != "1" ]; then
+	exit_fail
+fi
+
+val=`cat events/sample-trace/foo_bar_with_cond/enable`
+if [ "$val" != "1" ]; then
+	exit_fail
+fi
+
+clear_trace
+
-- 
2.45.2