Re: Linux 2.6.12-rc3

[Al Viro <viro@parcelfarce.linux.theplanet.co.uk>]

	thread_info part 2:

encapsulates the rest of arch-dependent operations with thread_info access.
Two new helpers - setup_thread_info() 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.

Again, normal platforms are obviously safe.  Note that end_of_stack() is
need since unlike the default case, m68k has only a single pointer in
stack - not the entire thread_info.  So DEBUG_STACK_USAGE needs to be
a bit different there.

diff -urN RC12-rc3-task_thread_info/include/linux/sched.h RC12-rc3-other_helpers/include/linux/sched.h
--- RC12-rc3-task_thread_info/include/linux/sched.h	Wed Apr 20 22:51:13 2005
+++ RC12-rc3-other_helpers/include/linux/sched.h	Wed Apr 20 22:51:15 2005
@@ -1104,6 +1104,16 @@
 
 #define task_thread_info(task) (task)->thread_info
 
+static inline void setup_thread_info(struct task_struct *p, struct thread_info *ti)
+{
+	*ti = *p->thread_info;
+}
+
+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 -urN RC12-rc3-task_thread_info/kernel/fork.c RC12-rc3-other_helpers/kernel/fork.c
--- RC12-rc3-task_thread_info/kernel/fork.c	Wed Apr 20 22:51:13 2005
+++ RC12-rc3-other_helpers/kernel/fork.c	Wed Apr 20 22:51:15 2005
@@ -169,8 +169,8 @@
 		return NULL;
 	}
 
-	*ti = *orig->thread_info;
 	*tsk = *orig;
+	setup_thread_info(tsk, ti);
 	tsk->thread_info = ti;
 	ti->task = tsk;
 
diff -urN RC12-rc3-task_thread_info/kernel/sched.c RC12-rc3-other_helpers/kernel/sched.c
--- RC12-rc3-task_thread_info/kernel/sched.c	Wed Apr 20 22:51:13 2005
+++ RC12-rc3-other_helpers/kernel/sched.c	Wed Apr 20 22:51:15 2005
@@ -3945,10 +3945,10 @@
 #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);
-
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