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

Gabriele Monaco
2025-04-11T12:31:30Z

On Fri, 2025-04-11 at 09:37 +0200, Nam Cao wrote:
> 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

We could get rid of RV_PER_TASK_MONITORS too I guess.

Rest looks good, thanks.

Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>

> -#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;
>   }