Revert "Input: implement SysRq as a separate input handler"

This reverts commit edc6e384f9d96e54a6d03068d3b03fa5b56b6449.

Also reverses the merge fixup patch applied to
kernel/debug/kdb/kdb_main.c.

5 files changed, 88 insertions, 226 deletions

diff --git a/drivers/char/keyboard.c b/drivers/char/keyboard.c
index 71f0a885a280..49306e51daf7 100644
--- a/drivers/char/keyboard.c
+++ b/drivers/char/keyboard.c
@@ -40,6 +40,7 @@
 #include <linux/kbd_kern.h>
 #include <linux/kbd_diacr.h>
 #include <linux/vt_kern.h>
+#include <linux/sysrq.h>
 #include <linux/input.h>
 #include <linux/reboot.h>
 #include <linux/notifier.h>
@@ -83,7 +84,8 @@ void compute_shiftstate(void);
 typedef void (k_handler_fn)(struct vc_data *vc, unsigned char value,
 			    char up_flag);
 static k_handler_fn K_HANDLERS;
-static k_handler_fn *k_handler[16] = { K_HANDLERS };
+k_handler_fn *k_handler[16] = { K_HANDLERS };
+EXPORT_SYMBOL_GPL(k_handler);
 
 #define FN_HANDLERS\
 	fn_null,	fn_enter,	fn_show_ptregs,	fn_show_mem,\
@@ -147,6 +149,22 @@ static struct ledptr {
 	unsigned char valid:1;
 } ledptrs[3];
 
+/* Simple translation table for the SysRq keys */
+
+#ifdef CONFIG_MAGIC_SYSRQ
+unsigned char kbd_sysrq_xlate[KEY_MAX + 1] =
+        "\000\0331234567890-=\177\t"                    /* 0x00 - 0x0f */
+        "qwertyuiop[]\r\000as"                          /* 0x10 - 0x1f */
+        "dfghjkl;'`\000\\zxcv"                          /* 0x20 - 0x2f */
+        "bnm,./\000*\000 \000\201\202\203\204\205"      /* 0x30 - 0x3f */
+        "\206\207\210\211\212\000\000789-456+1"         /* 0x40 - 0x4f */
+        "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
+        "\r\000/";                                      /* 0x60 - 0x6f */
+static int sysrq_down;
+static int sysrq_alt_use;
+#endif
+static int sysrq_alt;
+
 /*
  * Notifier list for console keyboard events
  */
@@ -1129,8 +1147,7 @@ static int emulate_raw(struct vc_data *vc, unsigned int keycode,
 			 * pressing PrtSc/SysRq alone, but simply 0x54
 			 * when pressing Alt+PrtSc/SysRq.
 			 */
-			if (test_bit(KEY_LEFTALT, key_down) ||
-			    test_bit(KEY_RIGHTALT, key_down)) {
+			if (sysrq_alt) {
 				put_queue(vc, 0x54 | up_flag);
 			} else {
 				put_queue(vc, 0xe0);
@@ -1198,6 +1215,8 @@ static void kbd_keycode(unsigned int keycode, int down, int hw_raw)
 
 	kbd = kbd_table + vc->vc_num;
 
+	if (keycode == KEY_LEFTALT || keycode == KEY_RIGHTALT)
+		sysrq_alt = down ? keycode : 0;
 #ifdef CONFIG_SPARC
 	if (keycode == KEY_STOP)
 		sparc_l1_a_state = down;
@@ -1211,6 +1230,21 @@ static void kbd_keycode(unsigned int keycode, int down, int hw_raw)
 				pr_warning("can't emulate rawmode for keycode %d\n",
 					   keycode);
 
+#ifdef CONFIG_MAGIC_SYSRQ	       /* Handle the SysRq Hack */
+	if (keycode == KEY_SYSRQ && (sysrq_down || (down == 1 && sysrq_alt))) {
+		if (!sysrq_down) {
+			sysrq_down = down;
+			sysrq_alt_use = sysrq_alt;
+		}
+		return;
+	}
+	if (sysrq_down && !down && keycode == sysrq_alt_use)
+		sysrq_down = 0;
+	if (sysrq_down && down && !rep) {
+		handle_sysrq(kbd_sysrq_xlate[keycode], tty);
+		return;
+	}
+#endif
 #ifdef CONFIG_SPARC
 	if (keycode == KEY_A && sparc_l1_a_state) {
 		sparc_l1_a_state = 0;
diff --git a/drivers/char/sysrq.c b/drivers/char/sysrq.c
index 1883dd8ee8f1..1ae2de7d8b4f 100644
--- a/drivers/char/sysrq.c
+++ b/drivers/char/sysrq.c
@@ -1,4 +1,7 @@
-/*
+/* -*- linux-c -*-
+ *
+ *	$Id: sysrq.c,v 1.15 1998/08/23 14:56:41 mj Exp $
+ *
  *	Linux Magic System Request Key Hacks
  *
  *	(c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
@@ -7,13 +10,8 @@
  *	(c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
  *	overhauled to use key registration
  *	based upon discusions in irc://irc.openprojects.net/#kernelnewbies
- *
- *	Copyright (c) 2010 Dmitry Torokhov
- *	Input handler conversion
  */
 
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-
 #include <linux/sched.h>
 #include <linux/interrupt.h>
 #include <linux/mm.h>
@@ -40,34 +38,33 @@
 #include <linux/workqueue.h>
 #include <linux/hrtimer.h>
 #include <linux/oom.h>
-#include <linux/input.h>
 
 #include <asm/ptrace.h>
 #include <asm/irq_regs.h>
 
 /* Whether we react on sysrq keys or just ignore them */
-static int __read_mostly sysrq_enabled = 1;
-static bool __read_mostly sysrq_always_enabled;
+int __read_mostly __sysrq_enabled = 1;
 
-static bool sysrq_on(void)
+static int __read_mostly sysrq_always_enabled;
+
+int sysrq_on(void)
 {
-	return sysrq_enabled || sysrq_always_enabled;
+	return __sysrq_enabled || sysrq_always_enabled;
 }
 
 /*
  * A value of 1 means 'all', other nonzero values are an op mask:
  */
-static bool sysrq_on_mask(int mask)
+static inline int sysrq_on_mask(int mask)
 {
-	return sysrq_always_enabled ||
-	       sysrq_enabled == 1 ||
-	       (sysrq_enabled & mask);
+	return sysrq_always_enabled || __sysrq_enabled == 1 ||
+						(__sysrq_enabled & mask);
 }
 
 static int __init sysrq_always_enabled_setup(char *str)
 {
-	sysrq_always_enabled = true;
-	pr_info("sysrq always enabled.\n");
+	sysrq_always_enabled = 1;
+	printk(KERN_INFO "debug: sysrq always enabled.\n");
 
 	return 1;
 }
@@ -78,7 +75,6 @@ __setup("sysrq_always_enabled", sysrq_always_enabled_setup);
 static void sysrq_handle_loglevel(int key, struct tty_struct *tty)
 {
 	int i;
-
 	i = key - '0';
 	console_loglevel = 7;
 	printk("Loglevel set to %d\n", i);
@@ -104,7 +100,7 @@ static struct sysrq_key_op sysrq_SAK_op = {
 	.enable_mask	= SYSRQ_ENABLE_KEYBOARD,
 };
 #else
-#define sysrq_SAK_op (*(struct sysrq_key_op *)NULL)
+#define sysrq_SAK_op (*(struct sysrq_key_op *)0)
 #endif
 
 #ifdef CONFIG_VT
@@ -122,7 +118,7 @@ static struct sysrq_key_op sysrq_unraw_op = {
 	.enable_mask	= SYSRQ_ENABLE_KEYBOARD,
 };
 #else
-#define sysrq_unraw_op (*(struct sysrq_key_op *)NULL)
+#define sysrq_unraw_op (*(struct sysrq_key_op *)0)
 #endif /* CONFIG_VT */
 
 static void sysrq_handle_crash(int key, struct tty_struct *tty)
@@ -198,7 +194,7 @@ static struct sysrq_key_op sysrq_showlocks_op = {
 	.action_msg	= "Show Locks Held",
 };
 #else
-#define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL)
+#define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
 #endif
 
 #ifdef CONFIG_SMP
@@ -301,7 +297,7 @@ static struct sysrq_key_op sysrq_ftrace_dump_op = {
 	.enable_mask	= SYSRQ_ENABLE_DUMP,
 };
 #else
-#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
+#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)0)
 #endif
 
 static void sysrq_handle_showmem(int key, struct tty_struct *tty)
@@ -480,7 +476,6 @@ struct sysrq_key_op *__sysrq_get_key_op(int key)
 	i = sysrq_key_table_key2index(key);
 	if (i != -1)
 	        op_p = sysrq_key_table[i];
-
         return op_p;
 }
 
@@ -492,7 +487,11 @@ static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
                 sysrq_key_table[i] = op_p;
 }
 
-static void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
+/*
+ * 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(int key, struct tty_struct *tty, int check_mask)
 {
 	struct sysrq_key_op *op_p;
 	int orig_log_level;
@@ -544,6 +543,10 @@ static void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
 	spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
 }
 
+/*
+ * This function is called by the keyboard handler when SysRq is pressed
+ * and any other keycode arrives.
+ */
 void handle_sysrq(int key, struct tty_struct *tty)
 {
 	if (sysrq_on())
@@ -551,148 +554,6 @@ void handle_sysrq(int key, struct tty_struct *tty)
 }
 EXPORT_SYMBOL(handle_sysrq);
 
-/* Simple translation table for the SysRq keys */
-static const unsigned char sysrq_xlate[KEY_MAX + 1] =
-        "\000\0331234567890-=\177\t"                    /* 0x00 - 0x0f */
-        "qwertyuiop[]\r\000as"                          /* 0x10 - 0x1f */
-        "dfghjkl;'`\000\\zxcv"                          /* 0x20 - 0x2f */
-        "bnm,./\000*\000 \000\201\202\203\204\205"      /* 0x30 - 0x3f */
-        "\206\207\210\211\212\000\000789-456+1"         /* 0x40 - 0x4f */
-        "230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
-        "\r\000/";                                      /* 0x60 - 0x6f */
-
-static bool sysrq_down;
-static int sysrq_alt_use;
-static int sysrq_alt;
-
-static bool sysrq_filter(struct input_handle *handle, unsigned int type,
-		         unsigned int code, int value)
-{
-
-	if (type != EV_KEY)
-		goto out;
-
-	switch (code) {
-
-	case KEY_LEFTALT:
-	case KEY_RIGHTALT:
-		if (value)
-			sysrq_alt = code;
-		else if (sysrq_down && code == sysrq_alt_use)
-			sysrq_down = false;
-		break;
-
-	case KEY_SYSRQ:
-		if (value == 1 && sysrq_alt) {
-			sysrq_down = true;
-			sysrq_alt_use = sysrq_alt;
-		}
-
-		break;
-
-	default:
-		if (sysrq_down && value && value != 2) {
-			struct vc_data *vc = vc_cons[fg_console].d;
-
-			__handle_sysrq(sysrq_xlate[code], vc->vc_tty, 1);
-		}
-	}
-
-out:
-	return sysrq_down;
-}
-
-static int sysrq_connect(struct input_handler *handler,
-			 struct input_dev *dev,
-			 const struct input_device_id *id)
-{
-	struct input_handle *handle;
-	int error;
-
-	sysrq_down = false;
-	sysrq_alt = 0;
-
-	handle = kzalloc(sizeof(struct input_handle), GFP_KERNEL);
-	if (!handle)
-		return -ENOMEM;
-
-	handle->dev = dev;
-	handle->handler = handler;
-	handle->name = "sysrq";
-
-	error = input_register_handle(handle);
-	if (error) {
-		pr_err("Failed to register input sysrq handler, error %d\n",
-			error);
-		goto err_free;
-	}
-
-	error = input_open_device(handle);
-	if (error) {
-		pr_err("Failed to open input device, error %d\n", error);
-		goto err_unregister;
-	}
-
-	return 0;
-
- err_unregister:
-	input_unregister_handle(handle);
- err_free:
-	kfree(handle);
-	return error;
-}
-
-static void sysrq_disconnect(struct input_handle *handle)
-{
-	input_close_device(handle);
-	input_unregister_handle(handle);
-	kfree(handle);
-}
-
-/*
- * We are matching on KEY_LEFTALT insteard of KEY_SYSRQ because not all
- * keyboards have SysRq ikey predefined and so user may add it to keymap
- * later, but we expect all such keyboards to have left alt.
- */
-static const struct input_device_id sysrq_ids[] = {
-	{
-		.flags = INPUT_DEVICE_ID_MATCH_EVBIT |
-				INPUT_DEVICE_ID_MATCH_KEYBIT,
-		.evbit = { BIT_MASK(EV_KEY) },
-		.keybit = { BIT_MASK(KEY_LEFTALT) },
-	},
-	{ },
-};
-
-static struct input_handler sysrq_handler = {
-	.filter		= sysrq_filter,
-	.connect	= sysrq_connect,
-	.disconnect	= sysrq_disconnect,
-	.name		= "sysrq",
-	.id_table	= sysrq_ids,
-};
-
-int sysrq_toggle_support(int enable_mask)
-{
-	bool was_enabled = sysrq_on();
-	int error;
-
-	sysrq_enabled = enable_mask;
-
-	if (was_enabled != sysrq_on()) {
-		if (sysrq_on()) {
-			error = input_register_handler(&sysrq_handler);
-			if (error)
-				pr_err("Failed to register input handler, error %d",
-					error);
-
-		} else
-			input_unregister_handler(&sysrq_handler);
-	}
-
-	return 0;
-}
-
 static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
                                 struct sysrq_key_op *remove_op_p)
 {
@@ -737,7 +598,6 @@ static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
 			return -EFAULT;
 		__handle_sysrq(c, NULL, 0);
 	}
-
 	return count;
 }
 
@@ -745,34 +605,10 @@ static const struct file_operations proc_sysrq_trigger_operations = {
 	.write		= write_sysrq_trigger,
 };
 
-static void sysrq_init_procfs(void)
-{
-	if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
-			 &proc_sysrq_trigger_operations))
-		pr_err("Failed to register proc interface\n");
-}
-
-#else
-
-static inline void sysrq_init_procfs(void)
-{
-}
-
-#endif
-
 static int __init sysrq_init(void)
 {
-	int error;
-
-	sysrq_init_procfs();
-
-	if (sysrq_on()) {
-		error = input_register_handler(&sysrq_handler);
-		if (error)
-			pr_err("Failed to register input handler, error %d",
-				error);
-	}
-
+	proc_create("sysrq-trigger", S_IWUSR, NULL, &proc_sysrq_trigger_operations);
 	return 0;
 }
 module_init(sysrq_init);
+#endif
diff --git a/include/linux/sysrq.h b/include/linux/sysrq.h
index 5f2bdef8f5d9..99adcdc0d3ca 100644
--- a/include/linux/sysrq.h
+++ b/include/linux/sysrq.h
@@ -39,29 +39,40 @@ struct sysrq_key_op {
 
 #ifdef CONFIG_MAGIC_SYSRQ
 
+extern int sysrq_on(void);
+
+/*
+ * Do not use this one directly:
+ */
+extern int __sysrq_enabled;
+
 /* Generic SysRq interface -- you may call it from any device driver, supplying
  * ASCII code of the key, pointer to registers and kbd/tty structs (if they
  * are available -- else NULL's).
  */
 
 void handle_sysrq(int key, struct tty_struct *tty);
+void __handle_sysrq(int key, struct tty_struct *tty, int check_mask);
 int register_sysrq_key(int key, struct sysrq_key_op *op);
 int unregister_sysrq_key(int key, struct sysrq_key_op *op);
 struct sysrq_key_op *__sysrq_get_key_op(int key);
 
-int sysrq_toggle_support(int enable_mask);
-
 #else
 
-static inline int register_sysrq_key(int key, struct sysrq_key_op *op)
+static inline int sysrq_on(void)
 {
-	return -EINVAL;
+	return 0;
 }
-
-static inline int unregister_sysrq_key(int key, struct sysrq_key_op *op)
+static inline int __reterr(void)
 {
 	return -EINVAL;
 }
+static inline void handle_sysrq(int key, struct tty_struct *tty)
+{
+}
+
+#define register_sysrq_key(ig,nore) __reterr()
+#define unregister_sysrq_key(ig,nore) __reterr()
 
 #endif
 
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index bad8e63e0a64..f1f9309effe8 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -1819,8 +1819,10 @@ static int kdb_sr(int argc, const char **argv)
 {
 	if (argc != 1)
 		return KDB_ARGCOUNT;
-
-	sysrq_toggle_support(1);
+	if (!__sysrq_enabled) {
+		kdb_printf("Auto activating sysrq\n");
+		__sysrq_enabled = 1;
+	}
 
 	kdb_trap_printk++;
 	handle_sysrq(*argv[1], NULL);
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 5f15e373ed64..56db6c4c269d 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -168,27 +168,6 @@ static int proc_taint(struct ctl_table *table, int write,
 			       void __user *buffer, size_t *lenp, loff_t *ppos);
 #endif
 
-#ifdef CONFIG_MAGIC_SYSRQ
-static int __sysrq_enabled; /* Note: sysrq code ises it's own private copy */
-
-static int sysrq_sysctl_handler(ctl_table *table, int write,
-				void __user *buffer, size_t *lenp,
-				loff_t *ppos)
-{
-	int error;
-
-	error = proc_dointvec(table, write, buffer, lenp, ppos);
-	if (error)
-		return error;
-
-	if (write)
-		sysrq_toggle_support(__sysrq_enabled);
-
-	return 0;
-}
-
-#endif
-
 static struct ctl_table root_table[];
 static struct ctl_table_root sysctl_table_root;
 static struct ctl_table_header root_table_header = {
@@ -590,7 +569,7 @@ static struct ctl_table kern_table[] = {
 		.data		= &__sysrq_enabled,
 		.maxlen		= sizeof (int),
 		.mode		= 0644,
-		.proc_handler	= sysrq_sysctl_handler,
+		.proc_handler	= proc_dointvec,
 	},
 #endif
 #ifdef CONFIG_PROC_SYSCTL