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

Nam Cao
2025-04-11T07:38:15Z

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@linutronix.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