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![Ben Dooks](/assets/img/avatar_default.png)
The __kthread_queue_delayed_work is not exported so make it static, to avoid the following sparse warning: kernel/kthread.c:869:6: warning: symbol '__kthread_queue_delayed_work' was not declared. Should it be static? Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1242 lines
34 KiB
C
1242 lines
34 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* Kernel thread helper functions.
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* Copyright (C) 2004 IBM Corporation, Rusty Russell.
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*
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* Creation is done via kthreadd, so that we get a clean environment
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* even if we're invoked from userspace (think modprobe, hotplug cpu,
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* etc.).
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*/
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#include <uapi/linux/sched/types.h>
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#include <linux/sched.h>
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#include <linux/sched/task.h>
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#include <linux/kthread.h>
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#include <linux/completion.h>
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#include <linux/err.h>
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#include <linux/cgroup.h>
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#include <linux/cpuset.h>
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#include <linux/unistd.h>
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#include <linux/file.h>
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#include <linux/export.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/freezer.h>
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#include <linux/ptrace.h>
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#include <linux/uaccess.h>
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#include <linux/numa.h>
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#include <trace/events/sched.h>
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static DEFINE_SPINLOCK(kthread_create_lock);
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static LIST_HEAD(kthread_create_list);
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struct task_struct *kthreadd_task;
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struct kthread_create_info
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{
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/* Information passed to kthread() from kthreadd. */
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int (*threadfn)(void *data);
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void *data;
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int node;
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/* Result passed back to kthread_create() from kthreadd. */
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struct task_struct *result;
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struct completion *done;
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struct list_head list;
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};
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struct kthread {
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unsigned long flags;
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unsigned int cpu;
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void *data;
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struct completion parked;
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struct completion exited;
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#ifdef CONFIG_BLK_CGROUP
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struct cgroup_subsys_state *blkcg_css;
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#endif
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};
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enum KTHREAD_BITS {
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KTHREAD_IS_PER_CPU = 0,
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KTHREAD_SHOULD_STOP,
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KTHREAD_SHOULD_PARK,
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};
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static inline void set_kthread_struct(void *kthread)
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{
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/*
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* We abuse ->set_child_tid to avoid the new member and because it
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* can't be wrongly copied by copy_process(). We also rely on fact
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* that the caller can't exec, so PF_KTHREAD can't be cleared.
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*/
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current->set_child_tid = (__force void __user *)kthread;
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}
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static inline struct kthread *to_kthread(struct task_struct *k)
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{
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WARN_ON(!(k->flags & PF_KTHREAD));
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return (__force void *)k->set_child_tid;
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}
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void free_kthread_struct(struct task_struct *k)
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{
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struct kthread *kthread;
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/*
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* Can be NULL if this kthread was created by kernel_thread()
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* or if kmalloc() in kthread() failed.
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*/
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kthread = to_kthread(k);
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#ifdef CONFIG_BLK_CGROUP
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WARN_ON_ONCE(kthread && kthread->blkcg_css);
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#endif
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kfree(kthread);
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}
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/**
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* kthread_should_stop - should this kthread return now?
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*
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* When someone calls kthread_stop() on your kthread, it will be woken
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* and this will return true. You should then return, and your return
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* value will be passed through to kthread_stop().
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*/
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bool kthread_should_stop(void)
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{
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return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags);
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}
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EXPORT_SYMBOL(kthread_should_stop);
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bool __kthread_should_park(struct task_struct *k)
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{
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return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(k)->flags);
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}
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EXPORT_SYMBOL_GPL(__kthread_should_park);
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/**
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* kthread_should_park - should this kthread park now?
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*
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* When someone calls kthread_park() on your kthread, it will be woken
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* and this will return true. You should then do the necessary
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* cleanup and call kthread_parkme()
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*
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* Similar to kthread_should_stop(), but this keeps the thread alive
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* and in a park position. kthread_unpark() "restarts" the thread and
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* calls the thread function again.
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*/
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bool kthread_should_park(void)
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{
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return __kthread_should_park(current);
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}
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EXPORT_SYMBOL_GPL(kthread_should_park);
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/**
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* kthread_freezable_should_stop - should this freezable kthread return now?
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* @was_frozen: optional out parameter, indicates whether %current was frozen
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*
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* kthread_should_stop() for freezable kthreads, which will enter
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* refrigerator if necessary. This function is safe from kthread_stop() /
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* freezer deadlock and freezable kthreads should use this function instead
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* of calling try_to_freeze() directly.
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*/
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bool kthread_freezable_should_stop(bool *was_frozen)
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{
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bool frozen = false;
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might_sleep();
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if (unlikely(freezing(current)))
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frozen = __refrigerator(true);
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if (was_frozen)
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*was_frozen = frozen;
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return kthread_should_stop();
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}
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EXPORT_SYMBOL_GPL(kthread_freezable_should_stop);
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/**
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* kthread_data - return data value specified on kthread creation
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* @task: kthread task in question
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*
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* Return the data value specified when kthread @task was created.
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* The caller is responsible for ensuring the validity of @task when
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* calling this function.
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*/
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void *kthread_data(struct task_struct *task)
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{
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return to_kthread(task)->data;
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}
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/**
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* kthread_probe_data - speculative version of kthread_data()
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* @task: possible kthread task in question
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*
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* @task could be a kthread task. Return the data value specified when it
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* was created if accessible. If @task isn't a kthread task or its data is
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* inaccessible for any reason, %NULL is returned. This function requires
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* that @task itself is safe to dereference.
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*/
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void *kthread_probe_data(struct task_struct *task)
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{
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struct kthread *kthread = to_kthread(task);
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void *data = NULL;
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probe_kernel_read(&data, &kthread->data, sizeof(data));
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return data;
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}
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static void __kthread_parkme(struct kthread *self)
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{
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for (;;) {
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/*
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* TASK_PARKED is a special state; we must serialize against
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* possible pending wakeups to avoid store-store collisions on
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* task->state.
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*
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* Such a collision might possibly result in the task state
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* changin from TASK_PARKED and us failing the
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* wait_task_inactive() in kthread_park().
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*/
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set_special_state(TASK_PARKED);
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if (!test_bit(KTHREAD_SHOULD_PARK, &self->flags))
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break;
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complete(&self->parked);
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schedule();
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}
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__set_current_state(TASK_RUNNING);
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}
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void kthread_parkme(void)
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{
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__kthread_parkme(to_kthread(current));
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}
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EXPORT_SYMBOL_GPL(kthread_parkme);
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static int kthread(void *_create)
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{
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/* Copy data: it's on kthread's stack */
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struct kthread_create_info *create = _create;
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int (*threadfn)(void *data) = create->threadfn;
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void *data = create->data;
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struct completion *done;
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struct kthread *self;
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int ret;
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self = kzalloc(sizeof(*self), GFP_KERNEL);
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set_kthread_struct(self);
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/* If user was SIGKILLed, I release the structure. */
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done = xchg(&create->done, NULL);
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if (!done) {
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kfree(create);
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do_exit(-EINTR);
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}
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if (!self) {
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create->result = ERR_PTR(-ENOMEM);
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complete(done);
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do_exit(-ENOMEM);
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}
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self->data = data;
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init_completion(&self->exited);
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init_completion(&self->parked);
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current->vfork_done = &self->exited;
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/* OK, tell user we're spawned, wait for stop or wakeup */
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__set_current_state(TASK_UNINTERRUPTIBLE);
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create->result = current;
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complete(done);
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schedule();
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ret = -EINTR;
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if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) {
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cgroup_kthread_ready();
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__kthread_parkme(self);
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ret = threadfn(data);
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}
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do_exit(ret);
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}
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/* called from do_fork() to get node information for about to be created task */
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int tsk_fork_get_node(struct task_struct *tsk)
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{
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#ifdef CONFIG_NUMA
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if (tsk == kthreadd_task)
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return tsk->pref_node_fork;
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#endif
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return NUMA_NO_NODE;
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}
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static void create_kthread(struct kthread_create_info *create)
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{
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int pid;
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#ifdef CONFIG_NUMA
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current->pref_node_fork = create->node;
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#endif
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/* We want our own signal handler (we take no signals by default). */
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pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD);
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if (pid < 0) {
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/* If user was SIGKILLed, I release the structure. */
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struct completion *done = xchg(&create->done, NULL);
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if (!done) {
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kfree(create);
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return;
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}
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create->result = ERR_PTR(pid);
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complete(done);
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}
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}
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static __printf(4, 0)
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struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data),
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void *data, int node,
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const char namefmt[],
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va_list args)
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{
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DECLARE_COMPLETION_ONSTACK(done);
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struct task_struct *task;
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struct kthread_create_info *create = kmalloc(sizeof(*create),
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GFP_KERNEL);
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if (!create)
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return ERR_PTR(-ENOMEM);
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create->threadfn = threadfn;
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create->data = data;
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create->node = node;
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create->done = &done;
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spin_lock(&kthread_create_lock);
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list_add_tail(&create->list, &kthread_create_list);
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spin_unlock(&kthread_create_lock);
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wake_up_process(kthreadd_task);
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/*
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* Wait for completion in killable state, for I might be chosen by
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* the OOM killer while kthreadd is trying to allocate memory for
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* new kernel thread.
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*/
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if (unlikely(wait_for_completion_killable(&done))) {
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/*
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* If I was SIGKILLed before kthreadd (or new kernel thread)
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* calls complete(), leave the cleanup of this structure to
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* that thread.
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*/
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if (xchg(&create->done, NULL))
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return ERR_PTR(-EINTR);
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/*
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* kthreadd (or new kernel thread) will call complete()
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* shortly.
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*/
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wait_for_completion(&done);
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}
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task = create->result;
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if (!IS_ERR(task)) {
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static const struct sched_param param = { .sched_priority = 0 };
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char name[TASK_COMM_LEN];
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/*
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* task is already visible to other tasks, so updating
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* COMM must be protected.
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*/
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vsnprintf(name, sizeof(name), namefmt, args);
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set_task_comm(task, name);
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/*
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* root may have changed our (kthreadd's) priority or CPU mask.
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* The kernel thread should not inherit these properties.
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*/
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sched_setscheduler_nocheck(task, SCHED_NORMAL, ¶m);
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set_cpus_allowed_ptr(task, cpu_all_mask);
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}
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kfree(create);
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return task;
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}
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/**
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* kthread_create_on_node - create a kthread.
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* @threadfn: the function to run until signal_pending(current).
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* @data: data ptr for @threadfn.
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* @node: task and thread structures for the thread are allocated on this node
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* @namefmt: printf-style name for the thread.
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*
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* Description: This helper function creates and names a kernel
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* thread. The thread will be stopped: use wake_up_process() to start
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* it. See also kthread_run(). The new thread has SCHED_NORMAL policy and
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* is affine to all CPUs.
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*
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* If thread is going to be bound on a particular cpu, give its node
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* in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE.
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* When woken, the thread will run @threadfn() with @data as its
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* argument. @threadfn() can either call do_exit() directly if it is a
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* standalone thread for which no one will call kthread_stop(), or
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* return when 'kthread_should_stop()' is true (which means
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* kthread_stop() has been called). The return value should be zero
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* or a negative error number; it will be passed to kthread_stop().
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*
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* Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR).
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*/
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struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
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void *data, int node,
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const char namefmt[],
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...)
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{
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struct task_struct *task;
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va_list args;
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va_start(args, namefmt);
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task = __kthread_create_on_node(threadfn, data, node, namefmt, args);
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va_end(args);
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return task;
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}
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EXPORT_SYMBOL(kthread_create_on_node);
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static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, long state)
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{
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unsigned long flags;
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if (!wait_task_inactive(p, state)) {
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WARN_ON(1);
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return;
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}
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/* It's safe because the task is inactive. */
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raw_spin_lock_irqsave(&p->pi_lock, flags);
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do_set_cpus_allowed(p, mask);
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p->flags |= PF_NO_SETAFFINITY;
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raw_spin_unlock_irqrestore(&p->pi_lock, flags);
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}
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static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state)
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{
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__kthread_bind_mask(p, cpumask_of(cpu), state);
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}
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void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask)
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{
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__kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE);
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}
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/**
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* kthread_bind - bind a just-created kthread to a cpu.
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* @p: thread created by kthread_create().
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* @cpu: cpu (might not be online, must be possible) for @k to run on.
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*
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* Description: This function is equivalent to set_cpus_allowed(),
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* except that @cpu doesn't need to be online, and the thread must be
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* stopped (i.e., just returned from kthread_create()).
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*/
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void kthread_bind(struct task_struct *p, unsigned int cpu)
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{
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__kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE);
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}
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EXPORT_SYMBOL(kthread_bind);
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/**
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* kthread_create_on_cpu - Create a cpu bound kthread
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* @threadfn: the function to run until signal_pending(current).
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* @data: data ptr for @threadfn.
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* @cpu: The cpu on which the thread should be bound,
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* @namefmt: printf-style name for the thread. Format is restricted
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* to "name.*%u". Code fills in cpu number.
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*
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* Description: This helper function creates and names a kernel thread
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* The thread will be woken and put into park mode.
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*/
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struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data),
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void *data, unsigned int cpu,
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const char *namefmt)
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{
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struct task_struct *p;
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p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt,
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cpu);
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if (IS_ERR(p))
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return p;
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kthread_bind(p, cpu);
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/* CPU hotplug need to bind once again when unparking the thread. */
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set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags);
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to_kthread(p)->cpu = cpu;
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return p;
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}
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/**
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* kthread_unpark - unpark a thread created by kthread_create().
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* @k: thread created by kthread_create().
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*
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* Sets kthread_should_park() for @k to return false, wakes it, and
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* waits for it to return. If the thread is marked percpu then its
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* bound to the cpu again.
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*/
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void kthread_unpark(struct task_struct *k)
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{
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struct kthread *kthread = to_kthread(k);
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/*
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* Newly created kthread was parked when the CPU was offline.
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* The binding was lost and we need to set it again.
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*/
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if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags))
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__kthread_bind(k, kthread->cpu, TASK_PARKED);
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clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
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/*
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* __kthread_parkme() will either see !SHOULD_PARK or get the wakeup.
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*/
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wake_up_state(k, TASK_PARKED);
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}
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EXPORT_SYMBOL_GPL(kthread_unpark);
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/**
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* kthread_park - park a thread created by kthread_create().
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* @k: thread created by kthread_create().
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*
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* Sets kthread_should_park() for @k to return true, wakes it, and
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* waits for it to return. This can also be called after kthread_create()
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* instead of calling wake_up_process(): the thread will park without
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* calling threadfn().
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*
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* Returns 0 if the thread is parked, -ENOSYS if the thread exited.
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* If called by the kthread itself just the park bit is set.
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*/
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int kthread_park(struct task_struct *k)
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{
|
|
struct kthread *kthread = to_kthread(k);
|
|
|
|
if (WARN_ON(k->flags & PF_EXITING))
|
|
return -ENOSYS;
|
|
|
|
if (WARN_ON_ONCE(test_bit(KTHREAD_SHOULD_PARK, &kthread->flags)))
|
|
return -EBUSY;
|
|
|
|
set_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
|
|
if (k != current) {
|
|
wake_up_process(k);
|
|
/*
|
|
* Wait for __kthread_parkme() to complete(), this means we
|
|
* _will_ have TASK_PARKED and are about to call schedule().
|
|
*/
|
|
wait_for_completion(&kthread->parked);
|
|
/*
|
|
* Now wait for that schedule() to complete and the task to
|
|
* get scheduled out.
|
|
*/
|
|
WARN_ON_ONCE(!wait_task_inactive(k, TASK_PARKED));
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_park);
|
|
|
|
/**
|
|
* kthread_stop - stop a thread created by kthread_create().
|
|
* @k: thread created by kthread_create().
|
|
*
|
|
* Sets kthread_should_stop() for @k to return true, wakes it, and
|
|
* waits for it to exit. This can also be called after kthread_create()
|
|
* instead of calling wake_up_process(): the thread will exit without
|
|
* calling threadfn().
|
|
*
|
|
* If threadfn() may call do_exit() itself, the caller must ensure
|
|
* task_struct can't go away.
|
|
*
|
|
* Returns the result of threadfn(), or %-EINTR if wake_up_process()
|
|
* was never called.
|
|
*/
|
|
int kthread_stop(struct task_struct *k)
|
|
{
|
|
struct kthread *kthread;
|
|
int ret;
|
|
|
|
trace_sched_kthread_stop(k);
|
|
|
|
get_task_struct(k);
|
|
kthread = to_kthread(k);
|
|
set_bit(KTHREAD_SHOULD_STOP, &kthread->flags);
|
|
kthread_unpark(k);
|
|
wake_up_process(k);
|
|
wait_for_completion(&kthread->exited);
|
|
ret = k->exit_code;
|
|
put_task_struct(k);
|
|
|
|
trace_sched_kthread_stop_ret(ret);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(kthread_stop);
|
|
|
|
int kthreadd(void *unused)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
|
|
/* 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_mems_allowed(node_states[N_MEMORY]);
|
|
|
|
current->flags |= PF_NOFREEZE;
|
|
cgroup_init_kthreadd();
|
|
|
|
for (;;) {
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
if (list_empty(&kthread_create_list))
|
|
schedule();
|
|
__set_current_state(TASK_RUNNING);
|
|
|
|
spin_lock(&kthread_create_lock);
|
|
while (!list_empty(&kthread_create_list)) {
|
|
struct kthread_create_info *create;
|
|
|
|
create = list_entry(kthread_create_list.next,
|
|
struct kthread_create_info, list);
|
|
list_del_init(&create->list);
|
|
spin_unlock(&kthread_create_lock);
|
|
|
|
create_kthread(create);
|
|
|
|
spin_lock(&kthread_create_lock);
|
|
}
|
|
spin_unlock(&kthread_create_lock);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
void __kthread_init_worker(struct kthread_worker *worker,
|
|
const char *name,
|
|
struct lock_class_key *key)
|
|
{
|
|
memset(worker, 0, sizeof(struct kthread_worker));
|
|
raw_spin_lock_init(&worker->lock);
|
|
lockdep_set_class_and_name(&worker->lock, key, name);
|
|
INIT_LIST_HEAD(&worker->work_list);
|
|
INIT_LIST_HEAD(&worker->delayed_work_list);
|
|
}
|
|
EXPORT_SYMBOL_GPL(__kthread_init_worker);
|
|
|
|
/**
|
|
* kthread_worker_fn - kthread function to process kthread_worker
|
|
* @worker_ptr: pointer to initialized kthread_worker
|
|
*
|
|
* This function implements the main cycle of kthread worker. It processes
|
|
* work_list until it is stopped with kthread_stop(). It sleeps when the queue
|
|
* is empty.
|
|
*
|
|
* The works are not allowed to keep any locks, disable preemption or interrupts
|
|
* when they finish. There is defined a safe point for freezing when one work
|
|
* finishes and before a new one is started.
|
|
*
|
|
* Also the works must not be handled by more than one worker at the same time,
|
|
* see also kthread_queue_work().
|
|
*/
|
|
int kthread_worker_fn(void *worker_ptr)
|
|
{
|
|
struct kthread_worker *worker = worker_ptr;
|
|
struct kthread_work *work;
|
|
|
|
/*
|
|
* FIXME: Update the check and remove the assignment when all kthread
|
|
* worker users are created using kthread_create_worker*() functions.
|
|
*/
|
|
WARN_ON(worker->task && worker->task != current);
|
|
worker->task = current;
|
|
|
|
if (worker->flags & KTW_FREEZABLE)
|
|
set_freezable();
|
|
|
|
repeat:
|
|
set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */
|
|
|
|
if (kthread_should_stop()) {
|
|
__set_current_state(TASK_RUNNING);
|
|
raw_spin_lock_irq(&worker->lock);
|
|
worker->task = NULL;
|
|
raw_spin_unlock_irq(&worker->lock);
|
|
return 0;
|
|
}
|
|
|
|
work = NULL;
|
|
raw_spin_lock_irq(&worker->lock);
|
|
if (!list_empty(&worker->work_list)) {
|
|
work = list_first_entry(&worker->work_list,
|
|
struct kthread_work, node);
|
|
list_del_init(&work->node);
|
|
}
|
|
worker->current_work = work;
|
|
raw_spin_unlock_irq(&worker->lock);
|
|
|
|
if (work) {
|
|
__set_current_state(TASK_RUNNING);
|
|
work->func(work);
|
|
} else if (!freezing(current))
|
|
schedule();
|
|
|
|
try_to_freeze();
|
|
cond_resched();
|
|
goto repeat;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_worker_fn);
|
|
|
|
static __printf(3, 0) struct kthread_worker *
|
|
__kthread_create_worker(int cpu, unsigned int flags,
|
|
const char namefmt[], va_list args)
|
|
{
|
|
struct kthread_worker *worker;
|
|
struct task_struct *task;
|
|
int node = NUMA_NO_NODE;
|
|
|
|
worker = kzalloc(sizeof(*worker), GFP_KERNEL);
|
|
if (!worker)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
kthread_init_worker(worker);
|
|
|
|
if (cpu >= 0)
|
|
node = cpu_to_node(cpu);
|
|
|
|
task = __kthread_create_on_node(kthread_worker_fn, worker,
|
|
node, namefmt, args);
|
|
if (IS_ERR(task))
|
|
goto fail_task;
|
|
|
|
if (cpu >= 0)
|
|
kthread_bind(task, cpu);
|
|
|
|
worker->flags = flags;
|
|
worker->task = task;
|
|
wake_up_process(task);
|
|
return worker;
|
|
|
|
fail_task:
|
|
kfree(worker);
|
|
return ERR_CAST(task);
|
|
}
|
|
|
|
/**
|
|
* kthread_create_worker - create a kthread worker
|
|
* @flags: flags modifying the default behavior of the worker
|
|
* @namefmt: printf-style name for the kthread worker (task).
|
|
*
|
|
* Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
|
|
* when the needed structures could not get allocated, and ERR_PTR(-EINTR)
|
|
* when the worker was SIGKILLed.
|
|
*/
|
|
struct kthread_worker *
|
|
kthread_create_worker(unsigned int flags, const char namefmt[], ...)
|
|
{
|
|
struct kthread_worker *worker;
|
|
va_list args;
|
|
|
|
va_start(args, namefmt);
|
|
worker = __kthread_create_worker(-1, flags, namefmt, args);
|
|
va_end(args);
|
|
|
|
return worker;
|
|
}
|
|
EXPORT_SYMBOL(kthread_create_worker);
|
|
|
|
/**
|
|
* kthread_create_worker_on_cpu - create a kthread worker and bind it
|
|
* it to a given CPU and the associated NUMA node.
|
|
* @cpu: CPU number
|
|
* @flags: flags modifying the default behavior of the worker
|
|
* @namefmt: printf-style name for the kthread worker (task).
|
|
*
|
|
* Use a valid CPU number if you want to bind the kthread worker
|
|
* to the given CPU and the associated NUMA node.
|
|
*
|
|
* A good practice is to add the cpu number also into the worker name.
|
|
* For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu).
|
|
*
|
|
* Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
|
|
* when the needed structures could not get allocated, and ERR_PTR(-EINTR)
|
|
* when the worker was SIGKILLed.
|
|
*/
|
|
struct kthread_worker *
|
|
kthread_create_worker_on_cpu(int cpu, unsigned int flags,
|
|
const char namefmt[], ...)
|
|
{
|
|
struct kthread_worker *worker;
|
|
va_list args;
|
|
|
|
va_start(args, namefmt);
|
|
worker = __kthread_create_worker(cpu, flags, namefmt, args);
|
|
va_end(args);
|
|
|
|
return worker;
|
|
}
|
|
EXPORT_SYMBOL(kthread_create_worker_on_cpu);
|
|
|
|
/*
|
|
* Returns true when the work could not be queued at the moment.
|
|
* It happens when it is already pending in a worker list
|
|
* or when it is being cancelled.
|
|
*/
|
|
static inline bool queuing_blocked(struct kthread_worker *worker,
|
|
struct kthread_work *work)
|
|
{
|
|
lockdep_assert_held(&worker->lock);
|
|
|
|
return !list_empty(&work->node) || work->canceling;
|
|
}
|
|
|
|
static void kthread_insert_work_sanity_check(struct kthread_worker *worker,
|
|
struct kthread_work *work)
|
|
{
|
|
lockdep_assert_held(&worker->lock);
|
|
WARN_ON_ONCE(!list_empty(&work->node));
|
|
/* Do not use a work with >1 worker, see kthread_queue_work() */
|
|
WARN_ON_ONCE(work->worker && work->worker != worker);
|
|
}
|
|
|
|
/* insert @work before @pos in @worker */
|
|
static void kthread_insert_work(struct kthread_worker *worker,
|
|
struct kthread_work *work,
|
|
struct list_head *pos)
|
|
{
|
|
kthread_insert_work_sanity_check(worker, work);
|
|
|
|
list_add_tail(&work->node, pos);
|
|
work->worker = worker;
|
|
if (!worker->current_work && likely(worker->task))
|
|
wake_up_process(worker->task);
|
|
}
|
|
|
|
/**
|
|
* kthread_queue_work - queue a kthread_work
|
|
* @worker: target kthread_worker
|
|
* @work: kthread_work to queue
|
|
*
|
|
* Queue @work to work processor @task for async execution. @task
|
|
* must have been created with kthread_worker_create(). Returns %true
|
|
* if @work was successfully queued, %false if it was already pending.
|
|
*
|
|
* Reinitialize the work if it needs to be used by another worker.
|
|
* For example, when the worker was stopped and started again.
|
|
*/
|
|
bool kthread_queue_work(struct kthread_worker *worker,
|
|
struct kthread_work *work)
|
|
{
|
|
bool ret = false;
|
|
unsigned long flags;
|
|
|
|
raw_spin_lock_irqsave(&worker->lock, flags);
|
|
if (!queuing_blocked(worker, work)) {
|
|
kthread_insert_work(worker, work, &worker->work_list);
|
|
ret = true;
|
|
}
|
|
raw_spin_unlock_irqrestore(&worker->lock, flags);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_queue_work);
|
|
|
|
/**
|
|
* kthread_delayed_work_timer_fn - callback that queues the associated kthread
|
|
* delayed work when the timer expires.
|
|
* @t: pointer to the expired timer
|
|
*
|
|
* The format of the function is defined by struct timer_list.
|
|
* It should have been called from irqsafe timer with irq already off.
|
|
*/
|
|
void kthread_delayed_work_timer_fn(struct timer_list *t)
|
|
{
|
|
struct kthread_delayed_work *dwork = from_timer(dwork, t, timer);
|
|
struct kthread_work *work = &dwork->work;
|
|
struct kthread_worker *worker = work->worker;
|
|
unsigned long flags;
|
|
|
|
/*
|
|
* This might happen when a pending work is reinitialized.
|
|
* It means that it is used a wrong way.
|
|
*/
|
|
if (WARN_ON_ONCE(!worker))
|
|
return;
|
|
|
|
raw_spin_lock_irqsave(&worker->lock, flags);
|
|
/* Work must not be used with >1 worker, see kthread_queue_work(). */
|
|
WARN_ON_ONCE(work->worker != worker);
|
|
|
|
/* Move the work from worker->delayed_work_list. */
|
|
WARN_ON_ONCE(list_empty(&work->node));
|
|
list_del_init(&work->node);
|
|
kthread_insert_work(worker, work, &worker->work_list);
|
|
|
|
raw_spin_unlock_irqrestore(&worker->lock, flags);
|
|
}
|
|
EXPORT_SYMBOL(kthread_delayed_work_timer_fn);
|
|
|
|
static void __kthread_queue_delayed_work(struct kthread_worker *worker,
|
|
struct kthread_delayed_work *dwork,
|
|
unsigned long delay)
|
|
{
|
|
struct timer_list *timer = &dwork->timer;
|
|
struct kthread_work *work = &dwork->work;
|
|
|
|
WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn);
|
|
|
|
/*
|
|
* If @delay is 0, queue @dwork->work immediately. This is for
|
|
* both optimization and correctness. The earliest @timer can
|
|
* expire is on the closest next tick and delayed_work users depend
|
|
* on that there's no such delay when @delay is 0.
|
|
*/
|
|
if (!delay) {
|
|
kthread_insert_work(worker, work, &worker->work_list);
|
|
return;
|
|
}
|
|
|
|
/* Be paranoid and try to detect possible races already now. */
|
|
kthread_insert_work_sanity_check(worker, work);
|
|
|
|
list_add(&work->node, &worker->delayed_work_list);
|
|
work->worker = worker;
|
|
timer->expires = jiffies + delay;
|
|
add_timer(timer);
|
|
}
|
|
|
|
/**
|
|
* kthread_queue_delayed_work - queue the associated kthread work
|
|
* after a delay.
|
|
* @worker: target kthread_worker
|
|
* @dwork: kthread_delayed_work to queue
|
|
* @delay: number of jiffies to wait before queuing
|
|
*
|
|
* If the work has not been pending it starts a timer that will queue
|
|
* the work after the given @delay. If @delay is zero, it queues the
|
|
* work immediately.
|
|
*
|
|
* Return: %false if the @work has already been pending. It means that
|
|
* either the timer was running or the work was queued. It returns %true
|
|
* otherwise.
|
|
*/
|
|
bool kthread_queue_delayed_work(struct kthread_worker *worker,
|
|
struct kthread_delayed_work *dwork,
|
|
unsigned long delay)
|
|
{
|
|
struct kthread_work *work = &dwork->work;
|
|
unsigned long flags;
|
|
bool ret = false;
|
|
|
|
raw_spin_lock_irqsave(&worker->lock, flags);
|
|
|
|
if (!queuing_blocked(worker, work)) {
|
|
__kthread_queue_delayed_work(worker, dwork, delay);
|
|
ret = true;
|
|
}
|
|
|
|
raw_spin_unlock_irqrestore(&worker->lock, flags);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_queue_delayed_work);
|
|
|
|
struct kthread_flush_work {
|
|
struct kthread_work work;
|
|
struct completion done;
|
|
};
|
|
|
|
static void kthread_flush_work_fn(struct kthread_work *work)
|
|
{
|
|
struct kthread_flush_work *fwork =
|
|
container_of(work, struct kthread_flush_work, work);
|
|
complete(&fwork->done);
|
|
}
|
|
|
|
/**
|
|
* kthread_flush_work - flush a kthread_work
|
|
* @work: work to flush
|
|
*
|
|
* If @work is queued or executing, wait for it to finish execution.
|
|
*/
|
|
void kthread_flush_work(struct kthread_work *work)
|
|
{
|
|
struct kthread_flush_work fwork = {
|
|
KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn),
|
|
COMPLETION_INITIALIZER_ONSTACK(fwork.done),
|
|
};
|
|
struct kthread_worker *worker;
|
|
bool noop = false;
|
|
|
|
worker = work->worker;
|
|
if (!worker)
|
|
return;
|
|
|
|
raw_spin_lock_irq(&worker->lock);
|
|
/* Work must not be used with >1 worker, see kthread_queue_work(). */
|
|
WARN_ON_ONCE(work->worker != worker);
|
|
|
|
if (!list_empty(&work->node))
|
|
kthread_insert_work(worker, &fwork.work, work->node.next);
|
|
else if (worker->current_work == work)
|
|
kthread_insert_work(worker, &fwork.work,
|
|
worker->work_list.next);
|
|
else
|
|
noop = true;
|
|
|
|
raw_spin_unlock_irq(&worker->lock);
|
|
|
|
if (!noop)
|
|
wait_for_completion(&fwork.done);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_flush_work);
|
|
|
|
/*
|
|
* This function removes the work from the worker queue. Also it makes sure
|
|
* that it won't get queued later via the delayed work's timer.
|
|
*
|
|
* The work might still be in use when this function finishes. See the
|
|
* current_work proceed by the worker.
|
|
*
|
|
* Return: %true if @work was pending and successfully canceled,
|
|
* %false if @work was not pending
|
|
*/
|
|
static bool __kthread_cancel_work(struct kthread_work *work, bool is_dwork,
|
|
unsigned long *flags)
|
|
{
|
|
/* Try to cancel the timer if exists. */
|
|
if (is_dwork) {
|
|
struct kthread_delayed_work *dwork =
|
|
container_of(work, struct kthread_delayed_work, work);
|
|
struct kthread_worker *worker = work->worker;
|
|
|
|
/*
|
|
* del_timer_sync() must be called to make sure that the timer
|
|
* callback is not running. The lock must be temporary released
|
|
* to avoid a deadlock with the callback. In the meantime,
|
|
* any queuing is blocked by setting the canceling counter.
|
|
*/
|
|
work->canceling++;
|
|
raw_spin_unlock_irqrestore(&worker->lock, *flags);
|
|
del_timer_sync(&dwork->timer);
|
|
raw_spin_lock_irqsave(&worker->lock, *flags);
|
|
work->canceling--;
|
|
}
|
|
|
|
/*
|
|
* Try to remove the work from a worker list. It might either
|
|
* be from worker->work_list or from worker->delayed_work_list.
|
|
*/
|
|
if (!list_empty(&work->node)) {
|
|
list_del_init(&work->node);
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* kthread_mod_delayed_work - modify delay of or queue a kthread delayed work
|
|
* @worker: kthread worker to use
|
|
* @dwork: kthread delayed work to queue
|
|
* @delay: number of jiffies to wait before queuing
|
|
*
|
|
* If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise,
|
|
* modify @dwork's timer so that it expires after @delay. If @delay is zero,
|
|
* @work is guaranteed to be queued immediately.
|
|
*
|
|
* Return: %true if @dwork was pending and its timer was modified,
|
|
* %false otherwise.
|
|
*
|
|
* A special case is when the work is being canceled in parallel.
|
|
* It might be caused either by the real kthread_cancel_delayed_work_sync()
|
|
* or yet another kthread_mod_delayed_work() call. We let the other command
|
|
* win and return %false here. The caller is supposed to synchronize these
|
|
* operations a reasonable way.
|
|
*
|
|
* This function is safe to call from any context including IRQ handler.
|
|
* See __kthread_cancel_work() and kthread_delayed_work_timer_fn()
|
|
* for details.
|
|
*/
|
|
bool kthread_mod_delayed_work(struct kthread_worker *worker,
|
|
struct kthread_delayed_work *dwork,
|
|
unsigned long delay)
|
|
{
|
|
struct kthread_work *work = &dwork->work;
|
|
unsigned long flags;
|
|
int ret = false;
|
|
|
|
raw_spin_lock_irqsave(&worker->lock, flags);
|
|
|
|
/* Do not bother with canceling when never queued. */
|
|
if (!work->worker)
|
|
goto fast_queue;
|
|
|
|
/* Work must not be used with >1 worker, see kthread_queue_work() */
|
|
WARN_ON_ONCE(work->worker != worker);
|
|
|
|
/* Do not fight with another command that is canceling this work. */
|
|
if (work->canceling)
|
|
goto out;
|
|
|
|
ret = __kthread_cancel_work(work, true, &flags);
|
|
fast_queue:
|
|
__kthread_queue_delayed_work(worker, dwork, delay);
|
|
out:
|
|
raw_spin_unlock_irqrestore(&worker->lock, flags);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_mod_delayed_work);
|
|
|
|
static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork)
|
|
{
|
|
struct kthread_worker *worker = work->worker;
|
|
unsigned long flags;
|
|
int ret = false;
|
|
|
|
if (!worker)
|
|
goto out;
|
|
|
|
raw_spin_lock_irqsave(&worker->lock, flags);
|
|
/* Work must not be used with >1 worker, see kthread_queue_work(). */
|
|
WARN_ON_ONCE(work->worker != worker);
|
|
|
|
ret = __kthread_cancel_work(work, is_dwork, &flags);
|
|
|
|
if (worker->current_work != work)
|
|
goto out_fast;
|
|
|
|
/*
|
|
* The work is in progress and we need to wait with the lock released.
|
|
* In the meantime, block any queuing by setting the canceling counter.
|
|
*/
|
|
work->canceling++;
|
|
raw_spin_unlock_irqrestore(&worker->lock, flags);
|
|
kthread_flush_work(work);
|
|
raw_spin_lock_irqsave(&worker->lock, flags);
|
|
work->canceling--;
|
|
|
|
out_fast:
|
|
raw_spin_unlock_irqrestore(&worker->lock, flags);
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* kthread_cancel_work_sync - cancel a kthread work and wait for it to finish
|
|
* @work: the kthread work to cancel
|
|
*
|
|
* Cancel @work and wait for its execution to finish. This function
|
|
* can be used even if the work re-queues itself. On return from this
|
|
* function, @work is guaranteed to be not pending or executing on any CPU.
|
|
*
|
|
* kthread_cancel_work_sync(&delayed_work->work) must not be used for
|
|
* delayed_work's. Use kthread_cancel_delayed_work_sync() instead.
|
|
*
|
|
* The caller must ensure that the worker on which @work was last
|
|
* queued can't be destroyed before this function returns.
|
|
*
|
|
* Return: %true if @work was pending, %false otherwise.
|
|
*/
|
|
bool kthread_cancel_work_sync(struct kthread_work *work)
|
|
{
|
|
return __kthread_cancel_work_sync(work, false);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_cancel_work_sync);
|
|
|
|
/**
|
|
* kthread_cancel_delayed_work_sync - cancel a kthread delayed work and
|
|
* wait for it to finish.
|
|
* @dwork: the kthread delayed work to cancel
|
|
*
|
|
* This is kthread_cancel_work_sync() for delayed works.
|
|
*
|
|
* Return: %true if @dwork was pending, %false otherwise.
|
|
*/
|
|
bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *dwork)
|
|
{
|
|
return __kthread_cancel_work_sync(&dwork->work, true);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync);
|
|
|
|
/**
|
|
* kthread_flush_worker - flush all current works on a kthread_worker
|
|
* @worker: worker to flush
|
|
*
|
|
* Wait until all currently executing or pending works on @worker are
|
|
* finished.
|
|
*/
|
|
void kthread_flush_worker(struct kthread_worker *worker)
|
|
{
|
|
struct kthread_flush_work fwork = {
|
|
KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn),
|
|
COMPLETION_INITIALIZER_ONSTACK(fwork.done),
|
|
};
|
|
|
|
kthread_queue_work(worker, &fwork.work);
|
|
wait_for_completion(&fwork.done);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_flush_worker);
|
|
|
|
/**
|
|
* kthread_destroy_worker - destroy a kthread worker
|
|
* @worker: worker to be destroyed
|
|
*
|
|
* Flush and destroy @worker. The simple flush is enough because the kthread
|
|
* worker API is used only in trivial scenarios. There are no multi-step state
|
|
* machines needed.
|
|
*/
|
|
void kthread_destroy_worker(struct kthread_worker *worker)
|
|
{
|
|
struct task_struct *task;
|
|
|
|
task = worker->task;
|
|
if (WARN_ON(!task))
|
|
return;
|
|
|
|
kthread_flush_worker(worker);
|
|
kthread_stop(task);
|
|
WARN_ON(!list_empty(&worker->work_list));
|
|
kfree(worker);
|
|
}
|
|
EXPORT_SYMBOL(kthread_destroy_worker);
|
|
|
|
#ifdef CONFIG_BLK_CGROUP
|
|
/**
|
|
* kthread_associate_blkcg - associate blkcg to current kthread
|
|
* @css: the cgroup info
|
|
*
|
|
* Current thread must be a kthread. The thread is running jobs on behalf of
|
|
* other threads. In some cases, we expect the jobs attach cgroup info of
|
|
* original threads instead of that of current thread. This function stores
|
|
* original thread's cgroup info in current kthread context for later
|
|
* retrieval.
|
|
*/
|
|
void kthread_associate_blkcg(struct cgroup_subsys_state *css)
|
|
{
|
|
struct kthread *kthread;
|
|
|
|
if (!(current->flags & PF_KTHREAD))
|
|
return;
|
|
kthread = to_kthread(current);
|
|
if (!kthread)
|
|
return;
|
|
|
|
if (kthread->blkcg_css) {
|
|
css_put(kthread->blkcg_css);
|
|
kthread->blkcg_css = NULL;
|
|
}
|
|
if (css) {
|
|
css_get(css);
|
|
kthread->blkcg_css = css;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(kthread_associate_blkcg);
|
|
|
|
/**
|
|
* kthread_blkcg - get associated blkcg css of current kthread
|
|
*
|
|
* Current thread must be a kthread.
|
|
*/
|
|
struct cgroup_subsys_state *kthread_blkcg(void)
|
|
{
|
|
struct kthread *kthread;
|
|
|
|
if (current->flags & PF_KTHREAD) {
|
|
kthread = to_kthread(current);
|
|
if (kthread)
|
|
return kthread->blkcg_css;
|
|
}
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL(kthread_blkcg);
|
|
#endif
|