Commit 86951599 authored Jun 22, 2010 by Peter Zijlstra Committed by Paul E. McKenney Jun 23, 2010

sched: silence PROVE_RCU in sched_fork()



Because cgroup_fork() is ran before sched_fork() [ from copy_process() ]
and the child's pid is not yet visible the child is pinned to its
cgroup. Therefore we can silence this warning.

A nicer solution would be moving cgroup_fork() to right after
dup_task_struct() and exclude PF_STARTING from task_subsys_state().

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

parent 94bfa3b6

kernel/sched.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -2494,7 +2494,16 @@ void sched_fork(struct task_struct *p, int clone_flags)
		if (p->sched_class->task_fork)
		p->sched_class->task_fork(p);

		/*
		* The child is not yet in the pid-hash so no cgroup attach races,
		* and the cgroup is pinned to this child due to cgroup_fork()
		* is ran before sched_fork().
		*
		* Silence PROVE_RCU.
		*/
		rcu_read_lock();
		set_task_cpu(p, cpu);
		rcu_read_unlock();

		#if defined(CONFIG_SCHEDSTATS) \|\| defined(CONFIG_TASK_DELAY_ACCT)
		if (likely(sched_info_on()))

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