Re: [patch] Re: Magic Alt-SysRq change in 2.6.18-rc1

[Paulo Marques]

Paulo Marques wrote:
> Roman Zippel wrote:
> > On Tue, 11 Jul 2006, Andrew Morton wrote:
> > [...]
> > > What, actually, is the problem?
> >
> > It changes the behaviour, it will annoy the hell out of people like me 
> > who have to deal with different kernels and expect this to just work. :-(
> > Since then has it been acceptable to just go ahead and break stuff? 
> > This problem doesn't really look unsolvable, so why is my request to 
> > fix the damn thing so unreasonable?
>
> Ok, what about this one?

It doesn't work :P

Ok, I've tested it this time and this new one works as expected. I can
use any of the sequences discussed and I can produce a SysRq every time.
Still, just pressing SysRq or any sequence that doesn't start with 
"press Alt -> press SysRq" seems unaffected.

--
Paulo Marques - www.grupopie.com

Pointy-Haired Boss: I don't see anything that could stand in our way.
           Dilbert: Sanity? Reality? The laws of physics?

Subject: allow the old behavior of Alt+SysRq+<key>

This should allow any order of Alt + SysRq press followed by any key
while still holding one of SysRq or Alt.

Signed-off-by: Paulo Marques <pmarques@xxxxxxxxxxxx>

--- ./drivers/char/keyboard.c.orig	2006-07-12 13:03:32.000000000 +0100
+++ ./drivers/char/keyboard.c	2006-07-12 20:39:21.000000000 +0100
@@ -150,7 +150,7 @@ unsigned char kbd_sysrq_xlate[KEY_MAX +
         "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;
+static int sysrq_active;
 #endif
 static int sysrq_alt;

@@ -1164,16 +1164,24 @@ static void kbd_keycode(unsigned int key
 				printk(KERN_WARNING "keyboard.c: 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;
+	if (keycode == KEY_SYSRQ) {
+		if (down) {
+			if(sysrq_alt)
+				sysrq_down = down;
+		} else {
+			sysrq_down = 0;
 		}
-		return;
 	}
-	if (sysrq_down && !down && keycode == sysrq_alt_use)
-		sysrq_down = 0;
-	if (sysrq_down && down && !rep) {
+
+	if (sysrq_down && sysrq_alt)
+		sysrq_active = 1;
+	else if (!sysrq_down && !sysrq_alt)
+		sysrq_active = 0;
+
+	if (keycode == KEY_SYSRQ && sysrq_active)
+		return;
+
+	if (sysrq_active && down && !rep) {
 		handle_sysrq(kbd_sysrq_xlate[keycode], regs, tty);
 		return;
 	}