From: Al Viro 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 Signed-off-by: Roman Zippel Signed-off-by: Andrew Morton --- include/linux/sched.h | 11 +++++++++++ kernel/fork.c | 3 +-- kernel/sched.c | 4 ++-- 3 files changed, 14 insertions(+), 4 deletions(-) diff -puN include/linux/sched.h~m68k-introduce-setup_thread_stack-end_of_stack include/linux/sched.h --- devel/include/linux/sched.h~m68k-introduce-setup_thread_stack-end_of_stack 2005-09-12 03:34:49.000000000 -0700 +++ devel-akpm/include/linux/sched.h 2005-09-12 03:34:49.000000000 -0700 @@ -1173,6 +1173,17 @@ static inline void task_unlock(struct ta #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 -puN kernel/fork.c~m68k-introduce-setup_thread_stack-end_of_stack kernel/fork.c --- devel/kernel/fork.c~m68k-introduce-setup_thread_stack-end_of_stack 2005-09-12 03:34:49.000000000 -0700 +++ devel-akpm/kernel/fork.c 2005-09-12 03:34:49.000000000 -0700 @@ -170,10 +170,9 @@ static struct task_struct *dup_task_stru 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 -puN kernel/sched.c~m68k-introduce-setup_thread_stack-end_of_stack kernel/sched.c --- devel/kernel/sched.c~m68k-introduce-setup_thread_stack-end_of_stack 2005-09-12 03:34:49.000000000 -0700 +++ devel-akpm/kernel/sched.c 2005-09-12 03:34:49.000000000 -0700 @@ -4365,10 +4365,10 @@ 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); _