diff options
| -rw-r--r-- | include/linux/kthread.h | 1 | ||||
| -rw-r--r-- | kernel/kthread.c | 68 |
2 files changed, 62 insertions, 7 deletions
diff --git a/include/linux/kthread.h b/include/linux/kthread.h index b11f53c1ba2e..30209bdf83a2 100644 --- a/include/linux/kthread.h +++ b/include/linux/kthread.h @@ -85,6 +85,7 @@ kthread_run_on_cpu(int (*threadfn)(void *data), void *data, void free_kthread_struct(struct task_struct *k); void kthread_bind(struct task_struct *k, unsigned int cpu); void kthread_bind_mask(struct task_struct *k, const struct cpumask *mask); +int kthread_affine_preferred(struct task_struct *p, const struct cpumask *mask); int kthread_stop(struct task_struct *k); int kthread_stop_put(struct task_struct *k); bool kthread_should_stop(void); diff --git a/kernel/kthread.c b/kernel/kthread.c index 26a839288a60..32d620a99f11 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -70,6 +70,7 @@ struct kthread { char *full_name; struct task_struct *task; struct list_head hotplug_node; + struct cpumask *preferred_affinity; }; enum KTHREAD_BITS { @@ -327,6 +328,11 @@ void __noreturn kthread_exit(long result) mutex_lock(&kthreads_hotplug_lock); list_del(&kthread->hotplug_node); mutex_unlock(&kthreads_hotplug_lock); + + if (kthread->preferred_affinity) { + kfree(kthread->preferred_affinity); + kthread->preferred_affinity = NULL; + } } do_exit(0); } @@ -355,9 +361,17 @@ EXPORT_SYMBOL(kthread_complete_and_exit); static void kthread_fetch_affinity(struct kthread *kthread, struct cpumask *cpumask) { - cpumask_and(cpumask, cpumask_of_node(kthread->node), - housekeeping_cpumask(HK_TYPE_KTHREAD)); + const struct cpumask *pref; + if (kthread->preferred_affinity) { + pref = kthread->preferred_affinity; + } else { + if (WARN_ON_ONCE(kthread->node == NUMA_NO_NODE)) + return; + pref = cpumask_of_node(kthread->node); + } + + cpumask_and(cpumask, pref, housekeeping_cpumask(HK_TYPE_KTHREAD)); if (cpumask_empty(cpumask)) cpumask_copy(cpumask, housekeeping_cpumask(HK_TYPE_KTHREAD)); } @@ -440,7 +454,7 @@ static int kthread(void *_create) self->started = 1; - if (!(current->flags & PF_NO_SETAFFINITY)) + if (!(current->flags & PF_NO_SETAFFINITY) && !self->preferred_affinity) kthread_affine_node(); ret = -EINTR; @@ -839,12 +853,53 @@ int kthreadd(void *unused) return 0; } +int kthread_affine_preferred(struct task_struct *p, const struct cpumask *mask) +{ + struct kthread *kthread = to_kthread(p); + cpumask_var_t affinity; + unsigned long flags; + int ret; + + if (!wait_task_inactive(p, TASK_UNINTERRUPTIBLE) || kthread->started) { + WARN_ON(1); + return -EINVAL; + } + + WARN_ON_ONCE(kthread->preferred_affinity); + + if (!zalloc_cpumask_var(&affinity, GFP_KERNEL)) + return -ENOMEM; + + kthread->preferred_affinity = kzalloc(sizeof(struct cpumask), GFP_KERNEL); + if (!kthread->preferred_affinity) { + ret = -ENOMEM; + goto out; + } + + mutex_lock(&kthreads_hotplug_lock); + cpumask_copy(kthread->preferred_affinity, mask); + WARN_ON_ONCE(!list_empty(&kthread->hotplug_node)); + list_add_tail(&kthread->hotplug_node, &kthreads_hotplug); + kthread_fetch_affinity(kthread, affinity); + + /* It's safe because the task is inactive. */ + raw_spin_lock_irqsave(&p->pi_lock, flags); + do_set_cpus_allowed(p, affinity); + raw_spin_unlock_irqrestore(&p->pi_lock, flags); + + mutex_unlock(&kthreads_hotplug_lock); +out: + free_cpumask_var(affinity); + + return 0; +} + /* * Re-affine kthreads according to their preferences * and the newly online CPU. The CPU down part is handled * by select_fallback_rq() which default re-affines to - * housekeepers in case the preferred affinity doesn't - * apply anymore. + * housekeepers from other nodes in case the preferred + * affinity doesn't apply anymore. */ static int kthreads_online_cpu(unsigned int cpu) { @@ -864,8 +919,7 @@ static int kthreads_online_cpu(unsigned int cpu) list_for_each_entry(k, &kthreads_hotplug, hotplug_node) { if (WARN_ON_ONCE((k->task->flags & PF_NO_SETAFFINITY) || - kthread_is_per_cpu(k->task) || - k->node == NUMA_NO_NODE)) { + kthread_is_per_cpu(k->task))) { ret = -EINVAL; continue; } |