提交 8f20a5e8 编写于 作者: P Paul E. McKenney

rcu: Make rcu_tasks_kthread()'s GP-wait loop allow preemption

The grace-period-wait loop in rcu_tasks_kthread() is under (unnecessary)
RCU protection, and therefore has no preemption points in a PREEMPT=n
kernel.  This commit therefore removes the RCU protection and inserts
cond_resched().
Reported-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
上级 176f8f7a
......@@ -467,7 +467,7 @@ static void check_holdout_task(struct task_struct *t,
(IS_ENABLED(CONFIG_NO_HZ_FULL) &&
!is_idle_task(t) && t->rcu_tasks_idle_cpu >= 0)) {
ACCESS_ONCE(t->rcu_tasks_holdout) = false;
list_del_rcu(&t->rcu_tasks_holdout_list);
list_del_init(&t->rcu_tasks_holdout_list);
put_task_struct(t);
return;
}
......@@ -573,6 +573,7 @@ static int __noreturn rcu_tasks_kthread(void *arg)
bool firstreport;
bool needreport;
int rtst;
struct task_struct *t1;
schedule_timeout_interruptible(HZ);
rtst = ACCESS_ONCE(rcu_task_stall_timeout);
......@@ -582,11 +583,11 @@ static int __noreturn rcu_tasks_kthread(void *arg)
lastreport = jiffies;
firstreport = true;
WARN_ON(signal_pending(current));
rcu_read_lock();
list_for_each_entry_rcu(t, &rcu_tasks_holdouts,
rcu_tasks_holdout_list)
list_for_each_entry_safe(t, t1, &rcu_tasks_holdouts,
rcu_tasks_holdout_list) {
check_holdout_task(t, needreport, &firstreport);
rcu_read_unlock();
cond_resched();
}
}
/*
......
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