linux-kernel - [PATCH 2/5] kernel/panic: move panic sysctls to its own file

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Date:   Fri, 18 Feb 2022 18:59:12 +0800
From:   tangmeng <tangmeng@...ontech.com>
To:     mcgrof@...nel.org, keescook@...omium.org, yzaikin@...gle.com
Cc:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        tangmeng <tangmeng@...ontech.com>
Subject: [PATCH 2/5] kernel/panic: move panic sysctls to its own file

kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.

To help with this maintenance let's start by moving sysctls to places
where they actually belong.  The proc sysctl maintainers do not want to
know what sysctl knobs you wish to add for your own piece of code, we
just care about the core logic.

All filesystem syctls now get reviewed by fs folks. This commit
follows the commit of fs, move the oops_all_cpu_backtrace sysctl to
its own file, kernel/panic.c.

Signed-off-by: tangmeng <tangmeng@...ontech.com>
---
 include/linux/panic.h |  6 ------
 kernel/panic.c        | 26 +++++++++++++++++++++++++-
 kernel/sysctl.c       | 11 -----------
 3 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/include/linux/panic.h b/include/linux/panic.h
index f5844908a089..e71161da69c4 100644
--- a/include/linux/panic.h
+++ b/include/linux/panic.h
@@ -15,12 +15,6 @@ extern void oops_enter(void);
 extern void oops_exit(void);
 extern bool oops_may_print(void);
 
-#ifdef CONFIG_SMP
-extern unsigned int sysctl_oops_all_cpu_backtrace;
-#else
-#define sysctl_oops_all_cpu_backtrace 0
-#endif /* CONFIG_SMP */
-
 extern int panic_timeout;
 extern unsigned long panic_print;
 extern int panic_on_oops;
diff --git a/kernel/panic.c b/kernel/panic.c
index 55b50e052ec3..8aa5c01b41b6 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -43,7 +43,9 @@
  * Should we dump all CPUs backtraces in an oops event?
  * Defaults to 0, can be changed via sysctl.
  */
-unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
+static unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
+#else
+#define sysctl_oops_all_cpu_backtrace 0
 #endif /* CONFIG_SMP */
 
 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
@@ -72,6 +74,28 @@ ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
 
 EXPORT_SYMBOL(panic_notifier_list);
 
+#if defined(CONFIG_SMP) && defined(CONFIG_SYSCTL)
+static struct ctl_table kern_panic_table[] = {
+	{
+		.procname       = "oops_all_cpu_backtrace",
+		.data           = &sysctl_oops_all_cpu_backtrace,
+		.maxlen         = sizeof(int),
+		.mode           = 0644,
+		.proc_handler   = proc_dointvec_minmax,
+		.extra1         = SYSCTL_ZERO,
+		.extra2         = SYSCTL_ONE,
+	},
+	{ }
+};
+
+static __init int kernel_panic_sysctls_init(void)
+{
+	register_sysctl_init("kernel", kern_panic_table);
+	return 0;
+}
+late_initcall(kernel_panic_sysctls_init);
+#endif
+
 static long no_blink(int state)
 {
 	return 0;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 682b3b3f2924..fa79967d4b87 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1928,17 +1928,6 @@ static struct ctl_table kern_table[] = {
 		.proc_handler	= proc_dointvec,
 	},
 #endif
-#ifdef CONFIG_SMP
-	{
-		.procname	= "oops_all_cpu_backtrace",
-		.data		= &sysctl_oops_all_cpu_backtrace,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
-		.extra2		= SYSCTL_ONE,
-	},
-#endif /* CONFIG_SMP */
 	{
 		.procname	= "pid_max",
 		.data		= &pid_max,
-- 
2.20.1