linux-kernel - [PATCH 1/1] Input: sysrq -- ensure sysrq_enabled and __sysrq

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Date:	Sat, 15 Jan 2011 20:23:57 +0000
From:	Andy Whitcroft <apw@...onical.com>
To:	Dmitry Torokhov <dtor@...l.ru>
Cc:	Andy Whitcroft <apw@...onical.com>, linux-input@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Arnd Bergmann <arnd@...db.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/1] Input: sysrq -- ensure sysrq_enabled and __sysrq_enabled are consistent

Currently sysrq_enabled and __sysrq_enabled are initialised separatly
and inconsitantly, leading to sysrq being actually enabled by reported
as not enabled in sysfs.  The first change to the sysfs configurable
synchronises these two:

    static int __read_mostly sysrq_enabled = 1;
    static int __sysrq_enabled;

Add a new configuration value which sets the default for these preventing
them becoming out of sync again.  Default this to 1 to mirror previous
behaviour.

Signed-off-by: Andy Whitcroft <apw@...onical.com>
---
 drivers/tty/sysrq.c |    2 +-
 kernel/sysctl.c     |    3 ++-
 lib/Kconfig.debug   |    9 +++++++++
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
index c556ed9..ba8cf87 100644
--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -46,7 +46,7 @@
 #include <asm/irq_regs.h>
 
 /* Whether we react on sysrq keys or just ignore them */
-static int __read_mostly sysrq_enabled = 1;
+static int __read_mostly sysrq_enabled = CONFIG_MAGIC_SYSRQ_DEFAULT;
 static bool __read_mostly sysrq_always_enabled;
 
 static bool sysrq_on(void)
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index bc86bb3..85fd935 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -170,7 +170,8 @@ static int proc_taint(struct ctl_table *table, int write,
 #endif
 
 #ifdef CONFIG_MAGIC_SYSRQ
-static int __sysrq_enabled; /* Note: sysrq code ises it's own private copy */
+/* Note: sysrq code uses it's own private copy */
+static int __sysrq_enabled = CONFIG_MAGIC_SYSRQ_DEFAULT;
 
 static int sysrq_sysctl_handler(ctl_table *table, int write,
 				void __user *buffer, size_t *lenp,
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 2d05adb..459105e 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -50,6 +50,15 @@ config MAGIC_SYSRQ
 	  keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
 	  unless you really know what this hack does.
 
+config MAGIC_SYSRQ_DEFAULT
+	int "Magic SysRq key default"
+	default 1
+        range 0 1
+	help
+	  Set the default value for the sysrq sysfs control to this value.
+	  Setting this to 1 will enable sysrq on boot, to 0 will disable
+	  sysrq on boot.
+
 config STRIP_ASM_SYMS
 	bool "Strip assembler-generated symbols during link"
 	default n
-- 
1.7.2.3

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