Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit f10e00f4 authored by Kirill Tkhai's avatar Kirill Tkhai Committed by Ingo Molnar
Browse files

sched/dl: Use dl_bw_of() under rcu_read_lock_sched() 



rq->rd is freed using call_rcu_sched(), so rcu_read_lock() to access it
is not enough. We should use either rcu_read_lock_sched() or preempt_disable().

Reported-by: default avatarSasha Levin <sasha.levin@oracle.com>
Suggested-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarKirill Tkhai <ktkhai@parallels.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Fixes: 66339c31 "sched: Use dl_bw_of() under RCU read lock"
Link: http://lkml.kernel.org/r/1412065417.20287.24.camel@tkhai


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 10a12983

kernel/sched/core.c

+16 −9
Original line number Diff line number Diff line
@@ -5264,6 +5264,7 @@ static int sched_cpu_inactive(struct notifier_block *nfb, 
{

	unsigned long flags;

	long cpu = (long)hcpu;

	struct dl_bw *dl_b;



	switch (action & ~CPU_TASKS_FROZEN) {

	case CPU_DOWN_PREPARE:
@@ -5271,15 +5272,19 @@ static int sched_cpu_inactive(struct notifier_block *nfb, 


		/* explicitly allow suspend */

		if (!(action & CPU_TASKS_FROZEN)) {

			struct dl_bw *dl_b = dl_bw_of(cpu);

			bool overflow;

			int cpus;



			rcu_read_lock_sched();

			dl_b = dl_bw_of(cpu);



			raw_spin_lock_irqsave(&dl_b->lock, flags);

			cpus = dl_bw_cpus(cpu);

			overflow = __dl_overflow(dl_b, cpus, 0, 0);

			raw_spin_unlock_irqrestore(&dl_b->lock, flags);



			rcu_read_unlock_sched();



			if (overflow)

				return notifier_from_errno(-EBUSY);

		}
@@ -7647,11 +7652,10 @@ static int sched_dl_global_constraints(void) 
	u64 runtime = global_rt_runtime();

	u64 period = global_rt_period();

	u64 new_bw = to_ratio(period, runtime);

	struct dl_bw *dl_b;

	int cpu, ret = 0;

	unsigned long flags;



	rcu_read_lock();



	/*

	 * Here we want to check the bandwidth not being set to some

	 * value smaller than the currently allocated bandwidth in
@@ -7662,25 +7666,27 @@ static int sched_dl_global_constraints(void) 
	 * solutions is welcome!

	 */

	for_each_possible_cpu(cpu) {

		struct dl_bw *dl_b = dl_bw_of(cpu);

		rcu_read_lock_sched();

		dl_b = dl_bw_of(cpu);



		raw_spin_lock_irqsave(&dl_b->lock, flags);

		if (new_bw < dl_b->total_bw)

			ret = -EBUSY;

		raw_spin_unlock_irqrestore(&dl_b->lock, flags);



		rcu_read_unlock_sched();



		if (ret)

			break;

	}



	rcu_read_unlock();



	return ret;

}



static void sched_dl_do_global(void)

{

	u64 new_bw = -1;

	struct dl_bw *dl_b;

	int cpu;

	unsigned long flags;
@@ -7690,18 +7696,19 @@ static void sched_dl_do_global(void) 
	if (global_rt_runtime() != RUNTIME_INF)

		new_bw = to_ratio(global_rt_period(), global_rt_runtime());



	rcu_read_lock();

	/*

	 * FIXME: As above...

	 */

	for_each_possible_cpu(cpu) {

		struct dl_bw *dl_b = dl_bw_of(cpu);

		rcu_read_lock_sched();

		dl_b = dl_bw_of(cpu);



		raw_spin_lock_irqsave(&dl_b->lock, flags);

		dl_b->bw = new_bw;

		raw_spin_unlock_irqrestore(&dl_b->lock, flags);



		rcu_read_unlock_sched();

	}

	rcu_read_unlock();

}



static int sched_rt_global_validate(void)