diff options
Diffstat (limited to 'kernel/kthread.c')
| -rw-r--r-- | kernel/kthread.c | 108 |
1 files changed, 102 insertions, 6 deletions
diff --git a/kernel/kthread.c b/kernel/kthread.c index b262f47046ca..3edaa380dc7b 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -1,13 +1,17 @@ // SPDX-License-Identifier: GPL-2.0-only /* Kernel thread helper functions. * Copyright (C) 2004 IBM Corporation, Rusty Russell. + * Copyright (C) 2009 Red Hat, Inc. * * Creation is done via kthreadd, so that we get a clean environment * even if we're invoked from userspace (think modprobe, hotplug cpu, * etc.). */ #include <uapi/linux/sched/types.h> +#include <linux/mm.h> +#include <linux/mmu_context.h> #include <linux/sched.h> +#include <linux/sched/mm.h> #include <linux/sched/task.h> #include <linux/kthread.h> #include <linux/completion.h> @@ -23,8 +27,10 @@ #include <linux/ptrace.h> #include <linux/uaccess.h> #include <linux/numa.h> +#include <linux/sched/isolation.h> #include <trace/events/sched.h> + static DEFINE_SPINLOCK(kthread_create_lock); static LIST_HEAD(kthread_create_list); struct task_struct *kthreadd_task; @@ -46,7 +52,9 @@ struct kthread_create_info struct kthread { unsigned long flags; unsigned int cpu; + int (*threadfn)(void *); void *data; + mm_segment_t oldfs; struct completion parked; struct completion exited; #ifdef CONFIG_BLK_CGROUP @@ -153,6 +161,20 @@ bool kthread_freezable_should_stop(bool *was_frozen) EXPORT_SYMBOL_GPL(kthread_freezable_should_stop); /** + * kthread_func - return the function specified on kthread creation + * @task: kthread task in question + * + * Returns NULL if the task is not a kthread. + */ +void *kthread_func(struct task_struct *task) +{ + if (task->flags & PF_KTHREAD) + return to_kthread(task)->threadfn; + return NULL; +} +EXPORT_SYMBOL_GPL(kthread_func); + +/** * kthread_data - return data value specified on kthread creation * @task: kthread task in question * @@ -164,6 +186,7 @@ void *kthread_data(struct task_struct *task) { return to_kthread(task)->data; } +EXPORT_SYMBOL_GPL(kthread_data); /** * kthread_probe_data - speculative version of kthread_data() @@ -179,7 +202,7 @@ void *kthread_probe_data(struct task_struct *task) struct kthread *kthread = to_kthread(task); void *data = NULL; - probe_kernel_read(&data, &kthread->data, sizeof(data)); + copy_from_kernel_nofault(&data, &kthread->data, sizeof(data)); return data; } @@ -199,8 +222,15 @@ static void __kthread_parkme(struct kthread *self) if (!test_bit(KTHREAD_SHOULD_PARK, &self->flags)) break; + /* + * Thread is going to call schedule(), do not preempt it, + * or the caller of kthread_park() may spend more time in + * wait_task_inactive(). + */ + preempt_disable(); complete(&self->parked); - schedule(); + schedule_preempt_disabled(); + preempt_enable(); } __set_current_state(TASK_RUNNING); } @@ -237,6 +267,7 @@ static int kthread(void *_create) do_exit(-ENOMEM); } + self->threadfn = threadfn; self->data = data; init_completion(&self->exited); init_completion(&self->parked); @@ -245,8 +276,14 @@ static int kthread(void *_create) /* OK, tell user we're spawned, wait for stop or wakeup */ __set_current_state(TASK_UNINTERRUPTIBLE); create->result = current; + /* + * Thread is going to call schedule(), do not preempt it, + * or the creator may spend more time in wait_task_inactive(). + */ + preempt_disable(); complete(done); - schedule(); + schedule_preempt_disabled(); + preempt_enable(); ret = -EINTR; if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) { @@ -347,7 +384,8 @@ struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data), * The kernel thread should not inherit these properties. */ sched_setscheduler_nocheck(task, SCHED_NORMAL, ¶m); - set_cpus_allowed_ptr(task, cpu_all_mask); + set_cpus_allowed_ptr(task, + housekeeping_cpumask(HK_FLAG_KTHREAD)); } kfree(create); return task; @@ -442,7 +480,6 @@ EXPORT_SYMBOL(kthread_bind); * to "name.*%u". Code fills in cpu number. * * Description: This helper function creates and names a kernel thread - * The thread will be woken and put into park mode. */ struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), void *data, unsigned int cpu, @@ -572,7 +609,7 @@ int kthreadd(void *unused) /* Setup a clean context for our children to inherit. */ set_task_comm(tsk, "kthreadd"); ignore_signals(tsk); - set_cpus_allowed_ptr(tsk, cpu_all_mask); + set_cpus_allowed_ptr(tsk, housekeeping_cpumask(HK_FLAG_KTHREAD)); set_mems_allowed(node_states[N_MEMORY]); current->flags |= PF_NOFREEZE; @@ -1190,6 +1227,65 @@ void kthread_destroy_worker(struct kthread_worker *worker) } EXPORT_SYMBOL(kthread_destroy_worker); +/** + * kthread_use_mm - make the calling kthread operate on an address space + * @mm: address space to operate on + */ +void kthread_use_mm(struct mm_struct *mm) +{ + struct mm_struct *active_mm; + struct task_struct *tsk = current; + + WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); + WARN_ON_ONCE(tsk->mm); + + task_lock(tsk); + /* Hold off tlb flush IPIs while switching mm's */ + local_irq_disable(); + active_mm = tsk->active_mm; + if (active_mm != mm) { + mmgrab(mm); + tsk->active_mm = mm; + } + tsk->mm = mm; + switch_mm_irqs_off(active_mm, mm, tsk); + local_irq_enable(); + task_unlock(tsk); +#ifdef finish_arch_post_lock_switch + finish_arch_post_lock_switch(); +#endif + + if (active_mm != mm) + mmdrop(active_mm); + + to_kthread(tsk)->oldfs = force_uaccess_begin(); +} +EXPORT_SYMBOL_GPL(kthread_use_mm); + +/** + * kthread_unuse_mm - reverse the effect of kthread_use_mm() + * @mm: address space to operate on + */ +void kthread_unuse_mm(struct mm_struct *mm) +{ + struct task_struct *tsk = current; + + WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); + WARN_ON_ONCE(!tsk->mm); + + force_uaccess_end(to_kthread(tsk)->oldfs); + + task_lock(tsk); + sync_mm_rss(mm); + local_irq_disable(); + tsk->mm = NULL; + /* active_mm is still 'mm' */ + enter_lazy_tlb(mm, tsk); + local_irq_enable(); + task_unlock(tsk); +} +EXPORT_SYMBOL_GPL(kthread_unuse_mm); + #ifdef CONFIG_BLK_CGROUP /** * kthread_associate_blkcg - associate blkcg to current kthread |