printk: move printk sysctl to printk/sysctl.c

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.

So move printk sysctl from kernel/sysctl.c to kernel/printk/sysctl.c.
Use register_sysctl() to register the sysctl interface.

[mcgrof@kernel.org: fixed compile issues when PRINTK is not set, commit log update]

Link: https://lkml.kernel.org/r/20211124231435.1445213-6-mcgrof@kernel.org
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Antti Palosaari <crope@iki.fi>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: James E.J. Bottomley <jejb@linux.ibm.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Julia Lawall <julia.lawall@inria.fr>
Cc: Kees Cook <keescook@chromium.org>
Cc: Lukas Middendorf <kernel@tuxforce.de>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Phillip Potter <phil@philpotter.co.uk>
Cc: Qing Wang <wangqing@vivo.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Stephen Kitt <steve@sk2.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/printk/Makefile b/kernel/printk/Makefile
index d118739874c0da81e59fca3845c5ad14264d2261..f5b388e810b9fca6acf4654bf428eabdd6761170 100644 (file)
--- a/kernel/printk/Makefile
+++ b/kernel/printk/Makefile
@@ -2,5 +2,8 @@
 obj-y  = printk.o
 obj-$(CONFIG_PRINTK)   += printk_safe.o
 obj-$(CONFIG_A11Y_BRAILLE_CONSOLE)     += braille.o
-obj-$(CONFIG_PRINTK)   += printk_ringbuffer.o
 obj-$(CONFIG_PRINTK_INDEX)     += index.o
+
+obj-$(CONFIG_PRINTK)                 += printk_support.o
+printk_support-y                    := printk_ringbuffer.o
+printk_support-$(CONFIG_SYSCTL)             += sysctl.o

diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
index 9f3ed2fdb72114286ffe7f3264664615d4c161de..6b1c4b399845b2c24e4fef3687eea15680de771a 100644 (file)
--- a/kernel/printk/internal.h
+++ b/kernel/printk/internal.h
@@ -4,6 +4,12 @@
  */
 #include <linux/percpu.h>
 
+#if defined(CONFIG_PRINTK) && defined(CONFIG_SYSCTL)
+void __init printk_sysctl_init(void);
+#else
+#define printk_sysctl_init() do { } while (0)
+#endif
+
 #ifdef CONFIG_PRINTK
 
 /* Flags for a single printk record. */

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 155229f0cf0f6dc0effff9575521520036d97b9c..363a493bded82981d9345aa34bd16bdc254ae67a 100644 (file)
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3211,6 +3211,7 @@ static int __init printk_late_init(void)
        ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "printk:online",
                                        console_cpu_notify, NULL);
        WARN_ON(ret < 0);
+       printk_sysctl_init();
        return 0;
 }
 late_initcall(printk_late_init);

diff --git a/kernel/printk/sysctl.c b/kernel/printk/sysctl.c
new file mode 100644 (file)
index 0000000..653ae04
--- /dev/null
+++ b/kernel/printk/sysctl.c
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * sysctl.c: General linux system control interface
+ */
+
+#include <linux/sysctl.h>
+#include <linux/printk.h>
+#include <linux/capability.h>
+#include <linux/ratelimit.h>
+#include "internal.h"
+
+static const int ten_thousand = 10000;
+
+static int proc_dointvec_minmax_sysadmin(struct ctl_table *table, int write,
+                               void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+       if (write && !capable(CAP_SYS_ADMIN))
+               return -EPERM;
+
+       return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+}
+
+static struct ctl_table printk_sysctls[] = {
+       {
+               .procname       = "printk",
+               .data           = &console_loglevel,
+               .maxlen         = 4*sizeof(int),
+               .mode           = 0644,
+               .proc_handler   = proc_dointvec,
+       },
+       {
+               .procname       = "printk_ratelimit",
+               .data           = &printk_ratelimit_state.interval,
+               .maxlen         = sizeof(int),
+               .mode           = 0644,
+               .proc_handler   = proc_dointvec_jiffies,
+       },
+       {
+               .procname       = "printk_ratelimit_burst",
+               .data           = &printk_ratelimit_state.burst,
+               .maxlen         = sizeof(int),
+               .mode           = 0644,
+               .proc_handler   = proc_dointvec,
+       },
+       {
+               .procname       = "printk_delay",
+               .data           = &printk_delay_msec,
+               .maxlen         = sizeof(int),
+               .mode           = 0644,
+               .proc_handler   = proc_dointvec_minmax,
+               .extra1         = SYSCTL_ZERO,
+               .extra2         = (void *)&ten_thousand,
+       },
+       {
+               .procname       = "printk_devkmsg",
+               .data           = devkmsg_log_str,
+               .maxlen         = DEVKMSG_STR_MAX_SIZE,
+               .mode           = 0644,
+               .proc_handler   = devkmsg_sysctl_set_loglvl,
+       },
+       {
+               .procname       = "dmesg_restrict",
+               .data           = &dmesg_restrict,
+               .maxlen         = sizeof(int),
+               .mode           = 0644,
+               .proc_handler   = proc_dointvec_minmax_sysadmin,
+               .extra1         = SYSCTL_ZERO,
+               .extra2         = SYSCTL_ONE,
+       },
+       {
+               .procname       = "kptr_restrict",
+               .data           = &kptr_restrict,
+               .maxlen         = sizeof(int),
+               .mode           = 0644,
+               .proc_handler   = proc_dointvec_minmax_sysadmin,
+               .extra1         = SYSCTL_ZERO,
+               .extra2         = SYSCTL_TWO,
+       },
+       {}
+};
+
+void __init printk_sysctl_init(void)
+{
+       register_sysctl_init("kernel", printk_sysctls);
+}

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index fb3cc7a1d4ad0f0031ec7c232c88bb0239e0ee4b..509f782483db06009a8503452f82e10156386b52 100644 (file)
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -908,17 +908,6 @@ static int proc_taint(struct ctl_table *table, int write,
        return err;
 }
 
-#ifdef CONFIG_PRINTK
-static int proc_dointvec_minmax_sysadmin(struct ctl_table *table, int write,
-                               void *buffer, size_t *lenp, loff_t *ppos)
-{
-       if (write && !capable(CAP_SYS_ADMIN))
-               return -EPERM;
-
-       return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
-}
-#endif
-
 /**
  * struct do_proc_dointvec_minmax_conv_param - proc_dointvec_minmax() range checking structure
  * @min: pointer to minimum allowable value
@@ -2210,63 +2199,6 @@ static struct ctl_table kern_table[] = {
                .mode           = 0644,
                .proc_handler   = proc_doulongvec_minmax,
        },
-#if defined CONFIG_PRINTK
-       {
-               .procname       = "printk",
-               .data           = &console_loglevel,
-               .maxlen         = 4*sizeof(int),
-               .mode           = 0644,
-               .proc_handler   = proc_dointvec,
-       },
-       {
-               .procname       = "printk_ratelimit",
-               .data           = &printk_ratelimit_state.interval,
-               .maxlen         = sizeof(int),
-               .mode           = 0644,
-               .proc_handler   = proc_dointvec_jiffies,
-       },
-       {
-               .procname       = "printk_ratelimit_burst",
-               .data           = &printk_ratelimit_state.burst,
-               .maxlen         = sizeof(int),
-               .mode           = 0644,
-               .proc_handler   = proc_dointvec,
-       },
-       {
-               .procname       = "printk_delay",
-               .data           = &printk_delay_msec,
-               .maxlen         = sizeof(int),
-               .mode           = 0644,
-               .proc_handler   = proc_dointvec_minmax,
-               .extra1         = SYSCTL_ZERO,
-               .extra2         = (void *)&ten_thousand,
-       },
-       {
-               .procname       = "printk_devkmsg",
-               .data           = devkmsg_log_str,
-               .maxlen         = DEVKMSG_STR_MAX_SIZE,
-               .mode           = 0644,
-               .proc_handler   = devkmsg_sysctl_set_loglvl,
-       },
-       {
-               .procname       = "dmesg_restrict",
-               .data           = &dmesg_restrict,
-               .maxlen         = sizeof(int),
-               .mode           = 0644,
-               .proc_handler   = proc_dointvec_minmax_sysadmin,
-               .extra1         = SYSCTL_ZERO,
-               .extra2         = SYSCTL_ONE,
-       },
-       {
-               .procname       = "kptr_restrict",
-               .data           = &kptr_restrict,
-               .maxlen         = sizeof(int),
-               .mode           = 0644,
-               .proc_handler   = proc_dointvec_minmax_sysadmin,
-               .extra1         = SYSCTL_ZERO,
-               .extra2         = SYSCTL_TWO,
-       },
-#endif
        {
                .procname       = "ngroups_max",
                .data           = (void *)&ngroups_max,