[PATCH] m68k: introduce setup_thread_stack() and end_of_stack()

encapsulates the rest of arch-dependent operations with thread_info access.
Two new helpers - setup_thread_stack() and end_of_stack().  For normal case
the former consists of copying thread_info of parent to new thread_info and
the latter returns pointer immediately past the end of thread_info.

Signed-off-by: Al Viro <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

kernel/sched.c

diff --git a/kernel/sched.c b/kernel/sched.c
index 831f7e9..6f46c94 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4327,10 +4327,10 @@
 #endif
 #ifdef CONFIG_DEBUG_STACK_USAGE
 	{
-		unsigned long *n = (unsigned long *) (p->thread_info+1);
+		unsigned long *n = end_of_stack(p);
 		while (!*n)
 			n++;
-		free = (unsigned long) n - (unsigned long)(p->thread_info+1);
+		free = (unsigned long)n - (unsigned long)end_of_stack(p);
 	}
 #endif
 	printk("%5lu %5d %6d ", free, p->pid, p->parent->pid);