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[PATCH] introduce TASK_DEAD state

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I am not sure about this patch, I am asking Ingo to take a decision.

task_struct->state == EXIT_DEAD is a very special case, to avoid a confusion
it makes sense to introduce a new state, TASK_DEAD, while EXIT_DEAD should
live only in ->exit_state as documented in sched.h.

Note that this state is not visible to user-space, get_task_state() masks off
unsuitable states.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Oleg Nesterov 2006-09-29 02:01:11 -07:00 committed by Linus Torvalds
parent 55a101f8f7
commit c394cc9fbb
4 changed files with 7 additions and 6 deletions
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1
include/linux/sched.h
View file

@ -148,6 +148,7 @@ extern unsigned long weighted_cpuload(const int cpu);
#define EXIT_DEAD 32 #define EXIT_DEAD 32
/* in tsk->state again */ /* in tsk->state again */
#define TASK_NONINTERACTIVE 64 #define TASK_NONINTERACTIVE 64
#define TASK_DEAD 128
#define __set_task_state(tsk, state_value) \ #define __set_task_state(tsk, state_value) \
do { (tsk)->state = (state_value); } while (0) do { (tsk)->state = (state_value); } while (0)

2
kernel/exit.c
View file

@ -955,7 +955,7 @@ fastcall NORET_TYPE void do_exit(long code)
preempt_disable(); preempt_disable();
/* causes final put_task_struct in finish_task_switch(). */ /* causes final put_task_struct in finish_task_switch(). */
tsk->state = EXIT_DEAD; tsk->state = TASK_DEAD;
schedule(); schedule();
BUG(); BUG();

8
kernel/sched.c
View file

@ -1761,10 +1761,10 @@ static inline void finish_task_switch(struct rq *rq, struct task_struct *prev)
/* /*
* A task struct has one reference for the use as "current". * A task struct has one reference for the use as "current".
* If a task dies, then it sets EXIT_DEAD in tsk->state and calls * If a task dies, then it sets TASK_DEAD in tsk->state and calls
* schedule one last time. The schedule call will never return, and * schedule one last time. The schedule call will never return, and
* the scheduled task must drop that reference. * the scheduled task must drop that reference.
* The test for EXIT_DEAD must occur while the runqueue locks are * The test for TASK_DEAD must occur while the runqueue locks are
* still held, otherwise prev could be scheduled on another cpu, die * still held, otherwise prev could be scheduled on another cpu, die
* there before we look at prev->state, and then the reference would * there before we look at prev->state, and then the reference would
* be dropped twice. * be dropped twice.
@ -1775,7 +1775,7 @@ static inline void finish_task_switch(struct rq *rq, struct task_struct *prev)
finish_lock_switch(rq, prev); finish_lock_switch(rq, prev);
if (mm) if (mm)
mmdrop(mm); mmdrop(mm);
if (unlikely(prev_state == EXIT_DEAD)) { if (unlikely(prev_state == TASK_DEAD)) {
/* /*
* Remove function-return probe instances associated with this * Remove function-return probe instances associated with this
* task and put them back on the free list. * task and put them back on the free list.
@ -5153,7 +5153,7 @@ static void migrate_dead(unsigned int dead_cpu, struct task_struct *p)
BUG_ON(p->exit_state != EXIT_ZOMBIE && p->exit_state != EXIT_DEAD); BUG_ON(p->exit_state != EXIT_ZOMBIE && p->exit_state != EXIT_DEAD);
/* Cannot have done final schedule yet: would have vanished. */ /* Cannot have done final schedule yet: would have vanished. */
BUG_ON(p->state == EXIT_DEAD); BUG_ON(p->state == TASK_DEAD);
get_task_struct(p); get_task_struct(p);

2
mm/oom_kill.c
View file

@ -227,7 +227,7 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
p->flags & PF_EXITING; p->flags & PF_EXITING;
if (releasing) { if (releasing) {
/* TASK_DEAD tasks have already released their mm */ /* TASK_DEAD tasks have already released their mm */
if (p->state == EXIT_DEAD) if (p->state == TASK_DEAD)
continue; continue;
if (p->flags & PF_EXITING && p == current) { if (p->flags & PF_EXITING && p == current) {
chosen = p; chosen = p;