rv: Pass va_list to reactors

The only thing the reactors can do with the passed in varargs is to
convert it into a va_list. Do that in a central helper instead.
It simplifies the reactors, removes some hairy macro-generated code
and introduces a convenient hook point to modify reactor behavior.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Link: https://lore.kernel.org/r/20251014-rv-lockdep-v1-1-0b9e51919ea8@linutronix.de
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>

include/linux/rv.h

@@ -88,7 +88,7 @@ union rv_task_monitor {
 struct rv_reactor {
 	const char		*name;
 	const char		*description;
-	__printf(1, 2) void	(*react)(const char *msg, ...);
+	__printf(1, 0) void	(*react)(const char *msg, va_list args);
 	struct list_head	list;
 };
 #endif
@@ -102,7 +102,7 @@ struct rv_monitor {
 	void			(*reset)(void);
 #ifdef CONFIG_RV_REACTORS
 	struct rv_reactor	*reactor;
-	__printf(1, 2) void	(*react)(const char *msg, ...);
+	__printf(1, 0) void	(*react)(const char *msg, va_list args);
 #endif
 	struct list_head	list;
 	struct rv_monitor	*parent;
@@ -119,11 +119,18 @@ void rv_put_task_monitor_slot(int slot);
 bool rv_reacting_on(void);
 int rv_unregister_reactor(struct rv_reactor *reactor);
 int rv_register_reactor(struct rv_reactor *reactor);
+__printf(2, 3)
+void rv_react(struct rv_monitor *monitor, const char *msg, ...);
 #else
 static inline bool rv_reacting_on(void)
 {
 	return false;
 }
+
+__printf(2, 3)
+static inline void rv_react(struct rv_monitor *monitor, const char *msg, ...)
+{
+}
 #endif /* CONFIG_RV_REACTORS */
 
 #endif /* CONFIG_RV */

include/rv/da_monitor.h

@@ -16,34 +16,19 @@
 #include <linux/bug.h>
 #include <linux/sched.h>
 
-#ifdef CONFIG_RV_REACTORS
-
-#define DECLARE_RV_REACTING_HELPERS(name, type)							\
-static void cond_react_##name(type curr_state, type event)					\
-{												\
-	if (!rv_reacting_on() || !rv_##name.react)						\
-		return;										\
-	rv_##name.react("rv: monitor %s does not allow event %s on state %s\n",			\
-			#name,									\
-			model_get_event_name_##name(event),					\
-			model_get_state_name_##name(curr_state));				\
-}
-
-#else /* CONFIG_RV_REACTOR */
-
-#define DECLARE_RV_REACTING_HELPERS(name, type)							\
-static void cond_react_##name(type curr_state, type event)					\
-{												\
-	return;											\
-}
-#endif
-
 /*
  * Generic helpers for all types of deterministic automata monitors.
  */
 #define DECLARE_DA_MON_GENERIC_HELPERS(name, type)						\
 												\
-DECLARE_RV_REACTING_HELPERS(name, type)								\
+static void react_##name(type curr_state, type event)						\
+{												\
+	rv_react(&rv_##name,									\
+		 "rv: monitor %s does not allow event %s on state %s\n",			\
+		 #name,										\
+		 model_get_event_name_##name(event),						\
+		 model_get_state_name_##name(curr_state));					\
+}												\
 												\
 /*												\
  * da_monitor_reset_##name - reset a monitor and setting it to init state			\
@@ -126,7 +111,7 @@ da_event_##name(struct da_monitor *da_mon, enum events_##name event)				\
 	for (int i = 0; i < MAX_DA_RETRY_RACING_EVENTS; i++) {					\
 		next_state = model_get_next_state_##name(curr_state, event);			\
 		if (next_state == INVALID_STATE) {						\
-			cond_react_##name(curr_state, event);					\
+			react_##name(curr_state, event);					\
 			trace_error_##name(model_get_state_name_##name(curr_state),		\
 					   model_get_event_name_##name(event));			\
 			return false;								\
@@ -165,7 +150,7 @@ static inline bool da_event_##name(struct da_monitor *da_mon, struct task_struct
 	for (int i = 0; i < MAX_DA_RETRY_RACING_EVENTS; i++) {					\
 		next_state = model_get_next_state_##name(curr_state, event);			\
 		if (next_state == INVALID_STATE) {						\
-			cond_react_##name(curr_state, event);					\
+			react_##name(curr_state, event);					\
 			trace_error_##name(tsk->pid,						\
 					   model_get_state_name_##name(curr_state),		\
 					   model_get_event_name_##name(event));			\

include/rv/ltl_monitor.h

@@ -16,21 +16,12 @@
 #error "Please include $(MODEL_NAME).h generated by rvgen"
 #endif
 
-#ifdef CONFIG_RV_REACTORS
 #define RV_MONITOR_NAME CONCATENATE(rv_, MONITOR_NAME)
-static struct rv_monitor RV_MONITOR_NAME;
 
-static void rv_cond_react(struct task_struct *task)
+#ifdef CONFIG_RV_REACTORS
-{
+static struct rv_monitor RV_MONITOR_NAME;
-	if (!rv_reacting_on() || !RV_MONITOR_NAME.react)
-		return;
-	RV_MONITOR_NAME.react("rv: "__stringify(MONITOR_NAME)": %s[%d]: violation detected\n",
-			      task->comm, task->pid);
-}
 #else
-static void rv_cond_react(struct task_struct *task)
+extern struct rv_monitor RV_MONITOR_NAME;
-{
-}
 #endif
 
 static int ltl_monitor_slot = RV_PER_TASK_MONITOR_INIT;
@@ -98,7 +89,8 @@ static void ltl_monitor_destroy(void)
 static void ltl_illegal_state(struct task_struct *task, struct ltl_monitor *mon)
 {
 	CONCATENATE(trace_error_, MONITOR_NAME)(task);
-	rv_cond_react(task);
+	rv_react(&RV_MONITOR_NAME, "rv: "__stringify(MONITOR_NAME)": %s[%d]: violation detected\n",
+		 task->comm, task->pid);
 }
 
 static void ltl_attempt_start(struct task_struct *task, struct ltl_monitor *mon)

kernel/trace/rv/reactor_panic.c

@@ -13,13 +13,9 @@
 #include <linux/init.h>
 #include <linux/rv.h>
 
-__printf(1, 2) static void rv_panic_reaction(const char *msg, ...)
+__printf(1, 0) static void rv_panic_reaction(const char *msg, va_list args)
 {
-	va_list args;
-
-	va_start(args, msg);
 	vpanic(msg, args);
-	va_end(args);
 }
 
 static struct rv_reactor rv_panic = {

kernel/trace/rv/reactor_printk.c

@@ -12,13 +12,9 @@
 #include <linux/init.h>
 #include <linux/rv.h>
 
-__printf(1, 2) static void rv_printk_reaction(const char *msg, ...)
+__printf(1, 0) static void rv_printk_reaction(const char *msg, va_list args)
 {
-	va_list args;
-
-	va_start(args, msg);
 	vprintk_deferred(msg, args);
-	va_end(args);
 }
 
 static struct rv_reactor rv_printk = {

kernel/trace/rv/rv_reactors.c

@@ -438,7 +438,7 @@ int reactor_populate_monitor(struct rv_monitor *mon)
 /*
  * Nop reactor register
  */
-__printf(1, 2) static void rv_nop_reaction(const char *msg, ...)
+__printf(1, 0) static void rv_nop_reaction(const char *msg, va_list args)
 {
 }
 
@@ -477,3 +477,17 @@ int init_rv_reactors(struct dentry *root_dir)
 out_err:
 	return -ENOMEM;
 }
+
+void rv_react(struct rv_monitor *monitor, const char *msg, ...)
+{
+	va_list args;
+
+	if (!rv_reacting_on() || !monitor->react)
+		return;
+
+	va_start(args, msg);
+
+	monitor->react(msg, args);
+
+	va_end(args);
+}