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authorIngo Molnar <mingo@elte.hu>2006-12-13 09:34:36 +0100
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-13 18:05:50 +0100
commit5d6f647fc6bb57377c9f417c4752e43189f56bb1 (patch)
treeab30c24c021adc549aab6bf042108d920975d9a9 /drivers/char/sysrq.c
parent[PATCH] optimize o_direct on block devices (diff)
downloadlinux-5d6f647fc6bb57377c9f417c4752e43189f56bb1.tar.xz
linux-5d6f647fc6bb57377c9f417c4752e43189f56bb1.zip
[PATCH] debug: add sysrq_always_enabled boot option
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>
Diffstat (limited to 'drivers/char/sysrq.c')
-rw-r--r--drivers/char/sysrq.c37
1 files changed, 31 insertions, 6 deletions
diff --git a/drivers/char/sysrq.c b/drivers/char/sysrq.c
index 05810c8d20bc..13935235e066 100644
--- a/drivers/char/sysrq.c
+++ b/drivers/char/sysrq.c
@@ -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);