Messages in this thread Patch in this message | | | Date | Thu, 24 Nov 2005 19:02:07 +0300 | From | Oleg Nesterov <> | Subject | [PATCH 1/2] PF_DEAD: cleanup usage |
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schedule() checks PF_DEAD on every context switch, and sets ->state = EXIT_DEAD to ensure that exited task will be deactivated.
I think it is better to set EXIT_DEAD in do_exit(), along with PF_DEAD flag.
It is safe to do without task_rq() locking, because concurrent try_to_wake_up() can't change task's ->state: the 'state' argument of try_to_wake_up() can't have EXIT_DEAD bit. And in case when try_to_wake_up() sees stale value of ->state == TASK_RUNNING it will do nothing.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
--- 2.6.15-rc2/kernel/exit.c~4_DEAD 2005-11-23 19:33:27.000000000 +0300 +++ 2.6.15-rc2/kernel/exit.c 2005-11-24 19:14:29.000000000 +0300 @@ -875,6 +875,7 @@ fastcall NORET_TYPE void do_exit(long co preempt_disable(); BUG_ON(tsk->flags & PF_DEAD); tsk->flags |= PF_DEAD; + tsk->state = EXIT_DEAD; schedule(); BUG(); --- 2.6.15-rc2/kernel/sched.c~4_DEAD 2005-11-22 19:35:52.000000000 +0300 +++ 2.6.15-rc2/kernel/sched.c 2005-11-24 19:13:34.000000000 +0300 @@ -3000,9 +3000,6 @@ need_resched_nonpreemptible: spin_lock_irq(&rq->lock); - if (unlikely(prev->flags & PF_DEAD)) - prev->state = EXIT_DEAD; - switch_count = &prev->nivcsw; if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) { switch_count = &prev->nvcsw; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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