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[PATCH] debug: add sysrq_always_enabled boot option

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Most distributions enable sysrq support but set it to 0 by default.  Add a
sysrq_always_enabled boot option to always-enable sysrq keys.  Useful for
debugging - without having to modify the disribution's config files (which
might not be possible if the kernel is on a live CD, etc.).

Also, while at it, clean up the sysrq interfaces.

[bunk@stusta.de: make sysrq_always_enabled_setup() static]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Ingo Molnar
2006-12-13 00:34:36 -08:00
committed by Linus Torvalds
parent e61c90188b
commit 5d6f647fc6
5 changed files with 60 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

37
drivers/char/sysrq.c
View File

@@ -41,7 +41,34 @@
#include <asm/irq_regs.h>
/* Whether we react on sysrq keys or just ignore them */
int sysrq_enabled = 1;
int __read_mostly __sysrq_enabled = 1;
static int __read_mostly sysrq_always_enabled;
int sysrq_on(void)
{
return __sysrq_enabled || sysrq_always_enabled;
}
/*
* A value of 1 means 'all', other nonzero values are an op mask:
*/
static inline int sysrq_on_mask(int mask)
{
return sysrq_always_enabled || __sysrq_enabled == 1 ||
(__sysrq_enabled & mask);
}
static int __init sysrq_always_enabled_setup(char *str)
{
sysrq_always_enabled = 1;
printk(KERN_INFO "debug: sysrq always enabled.\n");
return 1;
}
__setup("sysrq_always_enabled", sysrq_always_enabled_setup);
static void sysrq_handle_loglevel(int key, struct tty_struct *tty)
{
@@ -379,8 +406,7 @@ void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
* Should we check for enabled operations (/proc/sysrq-trigger
* should not) and is the invoked operation enabled?
*/
if (!check_mask || sysrq_enabled == 1 ||
(sysrq_enabled & op_p->enable_mask)) {
if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
printk("%s\n", op_p->action_msg);
console_loglevel = orig_log_level;
op_p->handler(key, tty);
@@ -414,9 +440,8 @@ void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
*/
void handle_sysrq(int key, struct tty_struct *tty)
{
if (!sysrq_enabled)
return;
__handle_sysrq(key, tty, 1);
if (sysrq_on())
__handle_sysrq(key, tty, 1);
}
EXPORT_SYMBOL(handle_sysrq);