Messages in this thread | | | Date | Fri, 1 Aug 2014 11:19:05 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH v2 tip/core/rcu 01/10] rcu: Add call_rcu_tasks() |
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On Fri, Aug 01, 2014 at 05:53:10PM +0200, Oleg Nesterov wrote: > On 07/30, Paul E. McKenney wrote: > > > > + rcu_read_lock(); > > + for_each_process_thread(g, t) { > > + if (t != current && ACCESS_ONCE(t->on_rq) && > > + !is_idle_task(t)) { > > + t->rcu_tasks_nvcsw = ACCESS_ONCE(t->nvcsw); > > + t->rcu_tasks_holdout = 1; > > + list_add(&t->rcu_tasks_holdout_list, > > + &rcu_tasks_holdouts); > > + } > > + } > > + rcu_read_unlock(); > > Wait, unless I missed something this can't work... > > The problem is, once the exiting task passes exit_notify() it can > be removed from rcu lists. > > Now suppose that (say) proc_exit_connector() has a probe, and this > task has jumped into trampoline and it was preempted there. > > No?
OK, this sounds to me like another vote for get_task_struct() as used in the v3 series. Or am I missing something?
Thanx, Paul
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