On Wed, Jun 26, 2019 at 03:47:16PM -0700, subhra mazumdar wrote:
> @@ -1082,6 +1088,37 @@ void do_set_cpus_allowed(struct task_struct *p, const
> struct cpumask *new_mask)
> put_prev_task(rq, p);
>
> p->sched_class->set_cpus_allowed(p, new_mask);
> + set_cpus_preferred_common(p, new_mask);
> +
> + if (queued)
> + enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
> + if (running)
> + set_curr_task(rq, p);
> +}
> +
> +void do_set_cpus_preferred(struct task_struct *p,
> + const struct cpumask *new_mask)
> +{
> + struct rq *rq = task_rq(p);
> + bool queued, running;
> +
> + lockdep_assert_held(&p->pi_lock);
> +
> + queued = task_on_rq_queued(p);
> + running = task_current(rq, p);
> +
> + if (queued) {
> + /*
> + * Because __kthread_bind() calls this on blocked tasks without
> + * holding rq->lock.
> + */
> + lockdep_assert_held(&rq->lock);
> + dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK);
> + }
> + if (running)
> + put_prev_task(rq, p);
> +
> + set_cpus_preferred_common(p, new_mask);
>
> if (queued)
> enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
> @@ -1170,6 +1207,41 @@ static int __set_cpus_allowed_ptr(struct task_struct
> *p,
> return ret;
> }
>
> +static int
> +__set_cpus_preferred_ptr(struct task_struct *p, const struct cpumask
> *new_mask)
> +{
> + const struct cpumask *cpu_valid_mask = cpu_active_mask;
> + unsigned int dest_cpu;
> + struct rq_flags rf;
> + struct rq *rq;
> + int ret = 0;
> +
> + rq = task_rq_lock(p, &rf);
> + update_rq_clock(rq);
> +
> + if (p->flags & PF_KTHREAD) {
> + /*
> + * Kernel threads are allowed on online && !active CPUs
> + */
> + cpu_valid_mask = cpu_online_mask;
> + }
> +
> + if (cpumask_equal(&p->cpus_preferred, new_mask))
> + goto out;
> +
> + if (!cpumask_intersects(new_mask, cpu_valid_mask)) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + do_set_cpus_preferred(p, new_mask);
> +
> +out:
> + task_rq_unlock(rq, p, &rf);
> +
> + return ret;
> +}
> +
> int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask
> *new_mask)
> {
> return __set_cpus_allowed_ptr(p, new_mask, false);
> @@ -4724,7 +4796,7 @@ SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct
> sched_attr __user *, uattr,
> return retval;
> }
>
> -long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
> +long sched_setaffinity(pid_t pid, const struct cpumask *in_mask, int flags)
> {
> cpumask_var_t cpus_allowed, new_mask;
> struct task_struct *p;
> @@ -4742,6 +4814,11 @@ long sched_setaffinity(pid_t pid, const struct cpumask
> *in_mask)
> get_task_struct(p);
> rcu_read_unlock();
>
> + if (flags == SCHED_SOFT_AFFINITY &&
> + p->sched_class != &fair_sched_class) {
> + retval = -EINVAL;
> + goto out_put_task;
> + }
> if (p->flags & PF_NO_SETAFFINITY) {
> retval = -EINVAL;
> goto out_put_task;
> @@ -4790,18 +4867,37 @@ long sched_setaffinity(pid_t pid, const struct
> cpumask *in_mask)
> }
> #endif
> again:
> - retval = __set_cpus_allowed_ptr(p, new_mask, true);
> -
> - if (!retval) {
> - cpuset_cpus_allowed(p, cpus_allowed);
> - if (!cpumask_subset(new_mask, cpus_allowed)) {
> - /*
> - * We must have raced with a concurrent cpuset
> - * update. Just reset the cpus_allowed to the
> - * cpuset's cpus_allowed
> - */
> - cpumask_copy(new_mask, cpus_allowed);
> - goto again;
> + if (flags == SCHED_HARD_AFFINITY) {
> + retval = __set_cpus_allowed_ptr(p, new_mask, true);
> +
> + if (!retval) {
> + cpuset_cpus_allowed(p, cpus_allowed);
> + if (!cpumask_subset(new_mask, cpus_allowed)) {
> + /*
> + * We must have raced with a concurrent cpuset
> + * update. Just reset the cpus_allowed to the
> + * cpuset's cpus_allowed
> + */
> + cpumask_copy(new_mask, cpus_allowed);
> + goto again;
> + }
> + p->affinity_unequal = false;
> + }
> + } else if (flags == SCHED_SOFT_AFFINITY) {
> + retval = __set_cpus_preferred_ptr(p, new_mask);
> + if (!retval) {
> + cpuset_cpus_allowed(p, cpus_allowed);
> + if (!cpumask_subset(new_mask, cpus_allowed)) {
> + /*
> + * We must have raced with a concurrent cpuset
> + * update.
> + */
> + cpumask_and(new_mask, new_mask, cpus_allowed);
> + goto again;
> + }
> + if (!cpumask_equal(&p->cpus_allowed,
> + &p->cpus_preferred))
> + p->affinity_unequal = true;
> }
> }
> out_free_new_mask:
This seems like a terrible lot of pointless duplication; don't you get a
much smaller diff by passing the hard/soft thing into
__set_cpus_allowed_ptr() and only branching where it matters?
