linux-kernel - [PATCH v2 22/22] rv: Allow to configure the number of per-task monitor

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Message-Id: <2591d725ec3dddfa27ad1826e7440fca71671770.1744355018.git.namcao@linutronix.de>
Date: Fri, 11 Apr 2025 09:37:38 +0200
From: Nam Cao <namcao@...utronix.de>
To: Steven Rostedt <rostedt@...dmis.org>,
	Gabriele Monaco <gmonaco@...hat.com>,
	linux-trace-kernel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: john.ogness@...utronix.de,
	Nam Cao <namcao@...utronix.de>
Subject: [PATCH v2 22/22] rv: Allow to configure the number of per-task monitor

Now that there are 2 monitors for real-time applications, users may want to
enable both of them simultaneously. Make the number of per-task monitor
configurable. Default it to 2 for now.

Signed-off-by: Nam Cao <namcao@...utronix.de>
---
 include/linux/rv.h      | 2 +-
 include/linux/sched.h   | 8 +++-----
 kernel/trace/rv/Kconfig | 9 +++++++++
 kernel/trace/rv/rv.c    | 8 ++++----
 4 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/include/linux/rv.h b/include/linux/rv.h
index c8320fa3a94b..204436a73bee 100644
--- a/include/linux/rv.h
+++ b/include/linux/rv.h
@@ -75,7 +75,7 @@ static inline bool rv_ltl_all_atoms_known(struct ltl_monitor *mon)
  * these are justified.
  */
 #define RV_PER_TASK_MONITORS		1
-#define RV_PER_TASK_MONITOR_INIT	(RV_PER_TASK_MONITORS)
+#define RV_PER_TASK_MONITOR_INIT	(CONFIG_RV_PER_TASK_MONITORS)
 
 union rv_task_monitor {
 	struct da_monitor	da_mon;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 45be0fa7a5cc..560782493292 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1623,12 +1623,10 @@ struct task_struct {
 
 #ifdef CONFIG_RV
 	/*
-	 * Per-task RV monitor. Nowadays fixed in RV_PER_TASK_MONITORS.
-	 * If we find justification for more monitors, we can think
-	 * about adding more or developing a dynamic method. So far,
-	 * none of these are justified.
+	 * Per-task RV monitor, fixed in CONFIG_RV_PER_TASK_MONITORS.
+	 * If memory becomes a concern, we can think about a dynamic method.
 	 */
-	union rv_task_monitor		rv[RV_PER_TASK_MONITORS];
+	union rv_task_monitor		rv[CONFIG_RV_PER_TASK_MONITORS];
 #endif
 
 #ifdef CONFIG_USER_EVENTS
diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig
index 942d57575e67..c11bf7e61ebf 100644
--- a/kernel/trace/rv/Kconfig
+++ b/kernel/trace/rv/Kconfig
@@ -32,6 +32,15 @@ menuconfig RV
 	  For further information, see:
 	    Documentation/trace/rv/runtime-verification.rst
 
+config RV_PER_TASK_MONITORS
+	int "Maximum number of per-task monitor"
+	depends on RV
+	range 1 8
+	default 2
+	help
+	  This option configures the maximum number of per-task RV monitors that can run
+	  simultaneously.
+
 source "kernel/trace/rv/monitors/wip/Kconfig"
 source "kernel/trace/rv/monitors/wwnr/Kconfig"
 source "kernel/trace/rv/monitors/sched/Kconfig"
diff --git a/kernel/trace/rv/rv.c b/kernel/trace/rv/rv.c
index d493fddf411f..ebd4b4b228bf 100644
--- a/kernel/trace/rv/rv.c
+++ b/kernel/trace/rv/rv.c
@@ -165,7 +165,7 @@ struct dentry *get_monitors_root(void)
 LIST_HEAD(rv_monitors_list);
 
 static int task_monitor_count;
-static bool task_monitor_slots[RV_PER_TASK_MONITORS];
+static bool task_monitor_slots[CONFIG_RV_PER_TASK_MONITORS];
 
 int rv_get_task_monitor_slot(void)
 {
@@ -173,12 +173,12 @@ int rv_get_task_monitor_slot(void)
 
 	lockdep_assert_held(&rv_interface_lock);
 
-	if (task_monitor_count == RV_PER_TASK_MONITORS)
+	if (task_monitor_count == CONFIG_RV_PER_TASK_MONITORS)
 		return -EBUSY;
 
 	task_monitor_count++;
 
-	for (i = 0; i < RV_PER_TASK_MONITORS; i++) {
+	for (i = 0; i < CONFIG_RV_PER_TASK_MONITORS; i++) {
 		if (task_monitor_slots[i] == false) {
 			task_monitor_slots[i] = true;
 			return i;
@@ -194,7 +194,7 @@ void rv_put_task_monitor_slot(int slot)
 {
 	lockdep_assert_held(&rv_interface_lock);
 
-	if (slot < 0 || slot >= RV_PER_TASK_MONITORS) {
+	if (slot < 0 || slot >= CONFIG_RV_PER_TASK_MONITORS) {
 		WARN_ONCE(1, "RV releasing an invalid slot!: %d\n", slot);
 		return;
 	}
-- 
2.39.5