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Commit e4099a5e authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
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sched/deadline: Fix up the smp-affinity mask tests 



For now deadline tasks are not allowed to set smp affinity; however
the current tests are wrong, cure this.

The test in __sched_setscheduler() also uses an on-stack cpumask_t
which is a no-no.

Change both tests to use cpumask_subset() such that we test the root
domain span to be a subset of the cpus_allowed mask. This way we're
sure the tasks can always run on all CPUs they can be balanced over,
and have no effective affinity constraints.

Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-fyqtb1lapxca3lhsxv9cumdc@git.kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 6bfd6d72

kernel/sched/core.c

+9 −19
Original line number Diff line number Diff line
@@ -3384,22 +3384,13 @@ change: 
#ifdef CONFIG_SMP

		if (dl_bandwidth_enabled() && dl_policy(policy)) {

			cpumask_t *span = rq->rd->span;

			cpumask_t act_affinity;



			/*

			 * cpus_allowed mask is statically initialized with

			 * CPU_MASK_ALL, span is instead dynamic. Here we

			 * compute the "dynamic" affinity of a task.

			 */

			cpumask_and(&act_affinity, &p->cpus_allowed,

				    cpu_active_mask);



			/*

			 * Don't allow tasks with an affinity mask smaller than

			 * the entire root_domain to become SCHED_DEADLINE. We

			 * will also fail if there's no bandwidth available.

			 */

			if (!cpumask_equal(&act_affinity, span) ||

			if (!cpumask_subset(span, &p->cpus_allowed) ||

			    rq->rd->dl_bw.bw == 0) {

				task_rq_unlock(rq, p, &flags);

				return -EPERM;
@@ -3420,8 +3411,7 @@ change: 
	 * of a SCHED_DEADLINE task) we need to check if enough bandwidth

	 * is available.

	 */

	if ((dl_policy(policy) || dl_task(p)) &&

	    dl_overflow(p, policy, attr)) {

	if ((dl_policy(policy) || dl_task(p)) && dl_overflow(p, policy, attr)) {

		task_rq_unlock(rq, p, &flags);

		return -EBUSY;

	}
@@ -3860,6 +3850,10 @@ long sched_setaffinity(pid_t pid, const struct cpumask *in_mask) 
	if (retval)

		goto out_unlock;





	cpuset_cpus_allowed(p, cpus_allowed);

	cpumask_and(new_mask, in_mask, cpus_allowed);



	/*

	 * Since bandwidth control happens on root_domain basis,

	 * if admission test is enabled, we only admit -deadline
@@ -3870,16 +3864,12 @@ long sched_setaffinity(pid_t pid, const struct cpumask *in_mask) 
	if (task_has_dl_policy(p)) {

		const struct cpumask *span = task_rq(p)->rd->span;



		if (dl_bandwidth_enabled() &&

		    !cpumask_equal(in_mask, span)) {

		if (dl_bandwidth_enabled() && !cpumask_subset(span, new_mask)) {

			retval = -EBUSY;

			goto out_unlock;

		}

	}

#endif



	cpuset_cpus_allowed(p, cpus_allowed);

	cpumask_and(new_mask, in_mask, cpus_allowed);

again:

	retval = set_cpus_allowed_ptr(p, new_mask);
@@ -4535,7 +4525,7 @@ EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr); 
 * When dealing with a -deadline task, we have to check if moving it to

 * a new CPU is possible or not. In fact, this is only true iff there

 * is enough bandwidth available on such CPU, otherwise we want the

 * whole migration progedure to fail over.

 * whole migration procedure to fail over.

 */

static inline

bool set_task_cpu_dl(struct task_struct *p, unsigned int cpu)