diff options
| -rw-r--r-- | include/linux/kthread.h | 2 | ||||
| -rw-r--r-- | kernel/kthread.c | 30 | ||||
| -rw-r--r-- | kernel/sched/core.c | 21 |
3 files changed, 35 insertions, 18 deletions
diff --git a/include/linux/kthread.h b/include/linux/kthread.h index 2484ed97e72f..d9133d6db308 100644 --- a/include/linux/kthread.h +++ b/include/linux/kthread.h @@ -33,6 +33,8 @@ struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), unsigned int cpu, const char *namefmt); +void set_kthread_struct(struct task_struct *p); + void kthread_set_per_cpu(struct task_struct *k, int cpu); bool kthread_is_per_cpu(struct task_struct *k); diff --git a/kernel/kthread.c b/kernel/kthread.c index fe3f2a40d61e..3d326833092b 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -68,16 +68,6 @@ enum KTHREAD_BITS { KTHREAD_SHOULD_PARK, }; -static inline void set_kthread_struct(void *kthread) -{ - /* - * We abuse ->set_child_tid to avoid the new member and because it - * can't be wrongly copied by copy_process(). We also rely on fact - * that the caller can't exec, so PF_KTHREAD can't be cleared. - */ - current->set_child_tid = (__force void __user *)kthread; -} - static inline struct kthread *to_kthread(struct task_struct *k) { WARN_ON(!(k->flags & PF_KTHREAD)); @@ -103,6 +93,22 @@ static inline struct kthread *__to_kthread(struct task_struct *p) return kthread; } +void set_kthread_struct(struct task_struct *p) +{ + struct kthread *kthread; + + if (__to_kthread(p)) + return; + + kthread = kzalloc(sizeof(*kthread), GFP_KERNEL); + /* + * We abuse ->set_child_tid to avoid the new member and because it + * can't be wrongly copied by copy_process(). We also rely on fact + * that the caller can't exec, so PF_KTHREAD can't be cleared. + */ + p->set_child_tid = (__force void __user *)kthread; +} + void free_kthread_struct(struct task_struct *k) { struct kthread *kthread; @@ -272,8 +278,8 @@ static int kthread(void *_create) struct kthread *self; int ret; - self = kzalloc(sizeof(*self), GFP_KERNEL); - set_kthread_struct(self); + set_kthread_struct(current); + self = to_kthread(current); /* If user was SIGKILLed, I release the structure. */ done = xchg(&create->done, NULL); diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 24fd795e4b8c..6a5124c4d54f 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8234,12 +8234,25 @@ void __init init_idle(struct task_struct *idle, int cpu) __sched_fork(0, idle); + /* + * The idle task doesn't need the kthread struct to function, but it + * is dressed up as a per-CPU kthread and thus needs to play the part + * if we want to avoid special-casing it in code that deals with per-CPU + * kthreads. + */ + set_kthread_struct(idle); + raw_spin_lock_irqsave(&idle->pi_lock, flags); raw_spin_rq_lock(rq); idle->state = TASK_RUNNING; idle->se.exec_start = sched_clock(); - idle->flags |= PF_IDLE; + /* + * PF_KTHREAD should already be set at this point; regardless, make it + * look like a proper per-CPU kthread. + */ + idle->flags |= PF_IDLE | PF_KTHREAD | PF_NO_SETAFFINITY; + kthread_set_per_cpu(idle, cpu); scs_task_reset(idle); kasan_unpoison_task_stack(idle); @@ -8456,12 +8469,8 @@ static void balance_push(struct rq *rq) /* * Both the cpu-hotplug and stop task are in this case and are * required to complete the hotplug process. - * - * XXX: the idle task does not match kthread_is_per_cpu() due to - * histerical raisins. */ - if (rq->idle == push_task || - kthread_is_per_cpu(push_task) || + if (kthread_is_per_cpu(push_task) || is_migration_disabled(push_task)) { /* |