Messages in this thread Patch in this message | | | Date | Fri, 23 Jun 2006 07:17:39 +0400 | From | Oleg Nesterov <> | Subject | [PATCH 2/2] sched_exit: move the callsite to do_exit() |
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sched_exit() is called by release_task(). If the task auto-reaps itself this call happens a bit too early (the task still uses cpu after that). If the task goes to TASK_ZOMBIE this call is unpredictably delayed.
I think it is better to do sched_exit() right before the last schedule().
We can use read_lock_rcu() instead of write_lock(tasklist). In that case it is possible that sched_exit() changes ->time_slice/->sleep_avg of the already dead ->parent, but I think this is tolerable.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
--- 2.6.17-rc6/kernel/sched.c~MOVE 2006-06-23 04:48:48.000000000 +0400 +++ 2.6.17-rc6/kernel/sched.c 2006-06-23 06:46:57.000000000 +0400 @@ -1479,10 +1479,13 @@ void fastcall wake_up_new_task(task_t *p */ void fastcall sched_exit(task_t *p) { - task_t *parent = p->parent; + task_t *parent; unsigned long flags; runqueue_t *rq; + rcu_read_lock(); + parent = p->real_parent; + /* * If the child was a (relative-) CPU hog then decrease * the sleep_avg of the parent as well. @@ -1498,6 +1501,7 @@ void fastcall sched_exit(task_t *p) (EXIT_WEIGHT + 1) * EXIT_WEIGHT + p->sleep_avg / (EXIT_WEIGHT + 1); task_rq_unlock(rq, &flags); + rcu_read_unlock(); } /** --- 2.6.17-rc6/kernel/exit.c~MOVE 2006-06-18 06:10:26.000000000 +0400 +++ 2.6.17-rc6/kernel/exit.c 2006-06-23 05:45:42.000000000 +0400 @@ -170,7 +170,6 @@ repeat: zap_leader = (leader->exit_signal == -1); } - sched_exit(p); write_unlock_irq(&tasklist_lock); spin_unlock(&p->proc_lock); proc_pid_flush(proc_dentry); @@ -940,6 +939,8 @@ fastcall NORET_TYPE void do_exit(long co if (tsk->splice_pipe) __free_pipe_info(tsk->splice_pipe); + sched_exit(tsk); + /* PF_DEAD causes final put_task_struct after we schedule. */ preempt_disable(); BUG_ON(tsk->flags & PF_DEAD); - 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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