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

Joel Granados
2025-05-09T12:55:30Z

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>
---
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)

--
2.47.2