[PATCH] Make /proc/sysrq-trigger ignore sysrq_enabled

It's silly that writing to /proc/sysrq-trigger does nothing if you haven't
enabled /proc/sys/kernel/sysrq.  So provide a new __handle_sysrq() which
ignores the sysrq_enabled check.

The patch also withdraws __handle_sysrq_nolock() from the kernel API.  It had
no callers.

drivers/char/sysrq.c

@@ -312,37 +312,19 @@ void __sysrq_put_key_op (int key, struct sysrq_key_op *op_p) {
                 sysrq_key_table[i] = op_p;
 }
 
-/*
- * This function is called by the keyboard handler when SysRq is pressed
- * and any other keycode arrives.
- */
-
-void handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty)
-{
-	if (!sysrq_enabled)
-		return;
-
-	__sysrq_lock_table();
-	__handle_sysrq_nolock(key, pt_regs, tty);
-	__sysrq_unlock_table();
-}
-
 /*
  * This is the non-locking version of handle_sysrq
  * It must/can only be called by sysrq key handlers,
  * as they are inside of the lock
  */
 
-void __handle_sysrq_nolock(int key, struct pt_regs *pt_regs,
-		  	   struct tty_struct *tty) 
+void __handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty)
 {
 	struct sysrq_key_op *op_p;
 	int orig_log_level;
 	int i, j;
 
-	if (!sysrq_enabled)
-		return;
-
+	__sysrq_lock_table();
 	orig_log_level = console_loglevel;
 	console_loglevel = 7;
 	printk(KERN_INFO "SysRq : ");
@@ -364,10 +346,22 @@ void __handle_sysrq_nolock(int key, struct pt_regs *pt_regs,
 		printk ("\n");
 		console_loglevel = orig_log_level;
 	}
+	__sysrq_unlock_table();
+}
+
+/*
+ * This function is called by the keyboard handler when SysRq is pressed
+ * and any other keycode arrives.
+ */
+
+void handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty)
+{
+	if (!sysrq_enabled)
+		return;
+	__handle_sysrq(key, pt_regs, tty);
 }
 
 EXPORT_SYMBOL(handle_sysrq);
-EXPORT_SYMBOL(__handle_sysrq_nolock);
 EXPORT_SYMBOL(__sysrq_lock_table);
 EXPORT_SYMBOL(__sysrq_unlock_table);
 EXPORT_SYMBOL(__sysrq_get_key_op);

fs/proc/proc_misc.c

@@ -631,7 +631,7 @@ static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
 
 		if (get_user(c, buf))
 			return -EFAULT;
-		handle_sysrq(c, NULL, NULL);
+		__handle_sysrq(c, NULL, NULL);
 	}
 	return count;
 }

include/linux/sysrq.h

@@ -30,13 +30,7 @@ struct sysrq_key_op {
  */
 
 void handle_sysrq(int, struct pt_regs *, struct tty_struct *);
-
-/* 
- * Nonlocking version of handle sysrq, used by sysrq handlers that need to
- * call sysrq handlers
- */
-
-void __handle_sysrq_nolock(int, struct pt_regs *, struct tty_struct *);
+void __handle_sysrq(int, struct pt_regs *, struct tty_struct *);
 
 /*
  * Sysrq registration manipulation functions