From: Roman Zippel <zippel@linux-m68k.org>
These four patches reduce the role of thread_info and makes the thread stack
more visible. The main change of these patches is the change from the
thread_info to the stack field in task_struct to abstract away the direct
access to the thread_info. I have been very careful with these changes (e.g.
I manually reverted the patches and compared the result to prevent typos), so
I'm quite sure these patches don't introduce any new problems.
This patch:
This adds a new field stack to task_struct. Its value is identical to
thread_info, but on m68k it doesn't point to the thread_info. This allows to
convert direct accesses to the thread_info field to either convert to using
the stack field, end_of_stack() or task_thread_info().
Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
include/asm-m68k/thread_info.h | 4 ++--
include/linux/init_task.h | 1 +
include/linux/sched.h | 5 +++--
kernel/fork.c | 1 +
4 files changed, 7 insertions(+), 4 deletions(-)
diff -puN include/asm-m68k/thread_info.h~add-stack-field-to-task_struct include/asm-m68k/thread_info.h
--- devel/include/asm-m68k/thread_info.h~add-stack-field-to-task_struct 2005-09-07 20:11:05.000000000 -0700
+++ devel-akpm/include/asm-m68k/thread_info.h 2005-09-07 20:11:05.000000000 -0700
@@ -42,11 +42,11 @@ struct thread_info {
#define __HAVE_THREAD_FUNCTIONS
#define setup_thread_stack(p, org) ({ \
- *(struct task_struct **)(p)->thread_info = (p); \
+ *(struct task_struct **)(p)->stack = (p); \
task_thread_info(p)->task = (p); \
})
-#define end_of_stack(p) ((unsigned long *)(p)->thread_info + 1)
+#define end_of_stack(p) ((unsigned long *)(p)->stack + 1)
/* entry.S relies on these definitions!
* bits 0-7 are tested at every exception exit
diff -puN include/linux/init_task.h~add-stack-field-to-task_struct include/linux/init_task.h
--- devel/include/linux/init_task.h~add-stack-field-to-task_struct 2005-09-07 20:11:05.000000000 -0700
+++ devel-akpm/include/linux/init_task.h 2005-09-07 20:11:05.000000000 -0700
@@ -71,6 +71,7 @@ extern struct group_info init_groups;
{ \
.state = 0, \
.thread_info = &init_thread_info, \
+ .stack = &init_stack, \
.usage = ATOMIC_INIT(2), \
.flags = 0, \
.lock_depth = -1, \
diff -puN include/linux/sched.h~add-stack-field-to-task_struct include/linux/sched.h
--- devel/include/linux/sched.h~add-stack-field-to-task_struct 2005-09-07 20:11:05.000000000 -0700
+++ devel-akpm/include/linux/sched.h 2005-09-07 20:11:05.000000000 -0700
@@ -635,6 +635,7 @@ struct mempolicy;
struct task_struct {
volatile long state; /* -1 unrunnable, 0 runnable, >0 stopped */
struct thread_info *thread_info;
+ void *stack;
atomic_t usage;
unsigned long flags; /* per process flags, defined below */
unsigned long ptrace;
@@ -1184,7 +1185,7 @@ static inline void task_unlock(struct ta
#ifndef __HAVE_THREAD_FUNCTIONS
-#define task_thread_info(task) (task)->thread_info
+#define task_thread_info(task) ((struct thread_info *)(task)->stack)
static inline void setup_thread_stack(struct task_struct *p, struct task_struct *org)
{
@@ -1194,7 +1195,7 @@ static inline void setup_thread_stack(st
static inline unsigned long *end_of_stack(struct task_struct *p)
{
- return (unsigned long *)(p->thread_info + 1);
+ return (unsigned long *)(task_thread_info(p) + 1);
}
#endif
diff -puN kernel/fork.c~add-stack-field-to-task_struct kernel/fork.c
--- devel/kernel/fork.c~add-stack-field-to-task_struct 2005-09-07 20:11:05.000000000 -0700
+++ devel-akpm/kernel/fork.c 2005-09-07 20:11:05.000000000 -0700
@@ -171,6 +171,7 @@ static struct task_struct *dup_task_stru
*tsk = *orig;
tsk->thread_info = ti;
+ tsk->stack = ti;
setup_thread_stack(tsk, orig);
/* One for us, one for whoever does the "release_task()" (usually parent) */
_