[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>

3 files changed, 14 insertions, 4 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index f8650314ba2f..e4681256e43e 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1235,6 +1235,17 @@ static inline void task_unlock(struct task_struct *p)
 
 #define task_thread_info(task) (task)->thread_info
 
+static inline void setup_thread_stack(struct task_struct *p, struct task_struct *org)
+{
+        *task_thread_info(p) = *task_thread_info(org);
+        task_thread_info(p)->task = p;
+}
+
+static inline unsigned long *end_of_stack(struct task_struct *p)
+{
+        return (unsigned long *)(p->thread_info + 1);
+}
+
 /* set thread flags in other task's structures
  * - see asm/thread_info.h for TIF_xxxx flags available
  */
diff --git a/kernel/fork.c b/kernel/fork.c
index 7ef352ce347b..2c70c9cdf5dc 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -171,10 +171,9 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
                 return NULL;
         }
 
-        *ti = *orig->thread_info;
         *tsk = *orig;
         tsk->thread_info = ti;
-        ti->task = tsk;
+        setup_thread_stack(tsk, orig);
 
         /* One for us, one for whoever does the "release_task()" (usually parent) */
         atomic_set(&tsk->usage,2);
diff --git a/kernel/sched.c b/kernel/sched.c
index 831f7e9d8f1c..6f46c94cc29e 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4327,10 +4327,10 @@ static void show_task(task_t *p)
 #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);