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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: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-fyqtb1lapxca3lhsxv9cumdc@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2013-12-17 10:03:34 +01:00 committed by Ingo Molnar
parent 6bfd6d72f5
commit e4099a5e92
1 changed files with 9 additions and 19 deletions
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28
kernel/sched/core.c
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@ -3384,23 +3384,14 @@ static int __sched_setscheduler(struct task_struct *p,
#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) ||
rq->rd->dl_bw.bw == 0) {
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 @@ static int __sched_setscheduler(struct task_struct *p,
* 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)