[tip:core/urgent] watchdog/sysctl: Get rid of the #ifdeffery

[tip-bot for Thomas Gleixner]

Commit-ID:  51d4052b01ca555e0d1d5fe297b309beb6c64aa0
Gitweb:     http://git.kernel.org/tip/51d4052b01ca555e0d1d5fe297b309beb6c64aa0
Author:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Tue, 12 Sep 2017 21:37:14 +0200
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 14 Sep 2017 11:41:07 +0200

watchdog/sysctl: Get rid of the #ifdeffery

The sysctl of the nmi_watchdog file prevents writes by setting:

    min = max = 0

if none of the users is enabled. That involves ifdeffery and is competely
non obvious.

If none of the facilities is enabeld, then the file can simply be made read
only. Move the ifdeffery into the header and use a constant for file
permissions.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Don Zickus <dzickus@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Chris Metcalf <cmetcalf@xxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Sebastian Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Ulrich Obergfell <uobergfe@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/20170912194147.706073616@xxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 include/linux/nmi.h | 6 ++++++
 kernel/sysctl.c     | 6 +-----
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index cfebb3b..5774b443 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -81,6 +81,12 @@ extern unsigned int hardlockup_panic;
 static inline void hardlockup_detector_disable(void) {}
 #endif
 
+#if defined(CONFIG_HAVE_NMI_WATCHDOG) || defined(CONFIG_HARDLOCKUP_DETECTOR)
+# define NMI_WATCHDOG_SYSCTL_PERM	0644
+#else
+# define NMI_WATCHDOG_SYSCTL_PERM	0444
+#endif
+
 #if defined(CONFIG_HARDLOCKUP_DETECTOR_PERF)
 extern void arch_touch_nmi_watchdog(void);
 extern void hardlockup_detector_perf_stop(void);
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 6648fbb..539cb4e 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -891,14 +891,10 @@ static struct ctl_table kern_table[] = {
 		.procname       = "nmi_watchdog",
 		.data           = &nmi_watchdog_enabled,
 		.maxlen         = sizeof (int),
-		.mode           = 0644,
+		.mode		= NMI_WATCHDOG_SYSCTL_PERM,
 		.proc_handler   = proc_nmi_watchdog,
 		.extra1		= &zero,
-#if defined(CONFIG_HAVE_NMI_WATCHDOG) || defined(CONFIG_HARDLOCKUP_DETECTOR)
 		.extra2		= &one,
-#else
-		.extra2		= &zero,
-#endif
 	},
 	{
 		.procname	= "watchdog_cpumask",