Re: [PATCH 03/12] rcu: Move rcu_stall related sysctls into rcu/tree_stall.h

Joel Fernandes
2025-05-09T13:14:28Z

On 5/9/2025 8:54 AM, Joel Granados wrote:
> Move sysctl_panic_on_rcu_stall and sysctl_max_rcu_stall_to_panic into
> the kernel/rcu subdirectory. Make these static in tree_stall.h and
> removed them as extern from panic.h as their scope is now confined into
> one file.
>
> This is part of a greater effort to move ctl tables into their
> respective subsystems which will reduce the merge conflicts in
> kernel/sysctl.c.
>
> Signed-off-by: Joel Granados <joel.granados@kernel.org>

For RCU:
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>

thanks,

- Joel

> ---
> include/linux/panic.h | 2 --
> kernel/rcu/tree_stall.h | 33 +++++++++++++++++++++++++++++++--
> kernel/sysctl.c | 20 --------------------
> 3 files changed, 31 insertions(+), 24 deletions(-)
>
> diff --git a/include/linux/panic.h b/include/linux/panic.h
> index 2494d51707ef422dfe191e484c0676e428a2de09..33ecead16b7c1af46aac07fb10b88beed5074b18 100644
> --- a/include/linux/panic.h
> +++ b/include/linux/panic.h
> @@ -27,8 +27,6 @@ extern int panic_on_warn;
> extern unsigned long panic_on_taint;
> extern bool panic_on_taint_nousertaint;
>
> -extern int sysctl_panic_on_rcu_stall;
> -extern int sysctl_max_rcu_stall_to_panic;
> extern int sysctl_panic_on_stackoverflow;
>
> extern bool crash_kexec_post_notifiers;
> diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
> index 925fcdad5dea22cfc8b0648546b78870cee485a6..5a0009b7e30b5a057856a3544f841712625699ce 100644
> --- a/kernel/rcu/tree_stall.h
> +++ b/kernel/rcu/tree_stall.h
> @@ -17,8 +17,37 @@
> // Controlling CPU stall warnings, including delay calculation.
>
> /* panic() on RCU Stall sysctl. */
> -int sysctl_panic_on_rcu_stall __read_mostly;
> -int sysctl_max_rcu_stall_to_panic __read_mostly;
> +static int sysctl_panic_on_rcu_stall __read_mostly;
> +static int sysctl_max_rcu_stall_to_panic __read_mostly;
> +
> +static const struct ctl_table rcu_stall_sysctl_table[] = {
> + {
> + .procname = "panic_on_rcu_stall",
> + .data = &sysctl_panic_on_rcu_stall,
> + .maxlen = sizeof(sysctl_panic_on_rcu_stall),
> + .mode = 0644,
> + .proc_handler = proc_dointvec_minmax,
> + .extra1 = SYSCTL_ZERO,
> + .extra2 = SYSCTL_ONE,
> + },
> + {
> + .procname = "max_rcu_stall_to_panic",
> + .data = &sysctl_max_rcu_stall_to_panic,
> + .maxlen = sizeof(sysctl_max_rcu_stall_to_panic),
> + .mode = 0644,
> + .proc_handler = proc_dointvec_minmax,
> + .extra1 = SYSCTL_ONE,
> + .extra2 = SYSCTL_INT_MAX,
> + },
> +};
> +
> +static int __init init_rcu_stall_sysctl(void)
> +{
> + register_sysctl_init("kernel", rcu_stall_sysctl_table);
> + return 0;
> +}
> +
> +subsys_initcall(init_rcu_stall_sysctl);
>
> #ifdef CONFIG_PROVE_RCU
> #define RCU_STALL_DELAY_DELTA (5 * HZ)
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index a22f35013da0d838ef421fc5d192f00d1e70fb0f..fd76f0e1d490940a67d72403d72d204ff13d888a 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -1706,26 +1706,6 @@ static const struct ctl_table kern_table[] = {
> .proc_handler = proc_dointvec,
> },
> #endif
> -#ifdef CONFIG_TREE_RCU
> - {
> - .procname = "panic_on_rcu_stall",
> - .data = &sysctl_panic_on_rcu_stall,
> - .maxlen = sizeof(sysctl_panic_on_rcu_stall),
> - .mode = 0644,
> - .proc_handler = proc_dointvec_minmax,
> - .extra1 = SYSCTL_ZERO,
> - .extra2 = SYSCTL_ONE,
> - },
> - {
> - .procname = "max_rcu_stall_to_panic",
> - .data = &sysctl_max_rcu_stall_to_panic,
> - .maxlen = sizeof(sysctl_max_rcu_stall_to_panic),
> - .mode = 0644,
> - .proc_handler = proc_dointvec_minmax,
> - .extra1 = SYSCTL_ONE,
> - .extra2 = SYSCTL_INT_MAX,
> - },
> -#endif
> };
>
> int __init sysctl_init_bases(void)
>