[PATCH] ppc32: don't recursively crash in die() on CHRP/PReP machines

This patch avoids recursive crash (leading to kernel stack overflow) in
die() on CHRP/PReP machines when CONFIG_PMAC_BACKLIGHT=y.  set_backlight_*
functions are placed in pmac section, which is discarded when _machine !=
_MACH_Pmac.

Signed-off-by: Jakub Bogusz <qboosh@pld-linux.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/ppc/kernel/traps.c

@@ -81,8 +81,10 @@ void die(const char * str, struct pt_regs * fp, long err)
 	console_verbose();
 	spin_lock_irq(&die_lock);
 #ifdef CONFIG_PMAC_BACKLIGHT
-	set_backlight_enable(1);
-	set_backlight_level(BACKLIGHT_MAX);
+	if (_machine == _MACH_Pmac) {
+		set_backlight_enable(1);
+		set_backlight_level(BACKLIGHT_MAX);
+	}
 #endif
 	printk("Oops: %s, sig: %ld [#%d]\n", str, err, ++die_counter);
 #ifdef CONFIG_PREEMPT