| // 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> |
| #include <linux/err.h> |
| #include <linux/cgroup.h> |
| #include <linux/cpuset.h> |
| #include <linux/unistd.h> |
| #include <linux/file.h> |
| #include <linux/export.h> |
| #include <linux/mutex.h> |
| #include <linux/slab.h> |
| #include <linux/freezer.h> |
| #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; |
| |
| struct kthread_create_info |
| { |
| /* Information passed to kthread() from kthreadd. */ |
| int (*threadfn)(void *data); |
| void *data; |
| int node; |
| |
| /* Result passed back to kthread_create() from kthreadd. */ |
| struct task_struct *result; |
| struct completion *done; |
| |
| struct list_head list; |
| }; |
| |
| 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 |
| struct cgroup_subsys_state *blkcg_css; |
| #endif |
| }; |
| |
| enum KTHREAD_BITS { |
| KTHREAD_IS_PER_CPU = 0, |
| KTHREAD_SHOULD_STOP, |
| 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)); |
| return (__force void *)k->set_child_tid; |
| } |
| |
| /* |
| * Variant of to_kthread() that doesn't assume @p is a kthread. |
| * |
| * Per construction; when: |
| * |
| * (p->flags & PF_KTHREAD) && p->set_child_tid |
| * |
| * the task is both a kthread and struct kthread is persistent. However |
| * PF_KTHREAD on it's own is not, kernel_thread() can exec() (See umh.c and |
| * begin_new_exec()). |
| */ |
| static inline struct kthread *__to_kthread(struct task_struct *p) |
| { |
| void *kthread = (__force void *)p->set_child_tid; |
| if (kthread && !(p->flags & PF_KTHREAD)) |
| kthread = NULL; |
| return kthread; |
| } |
| |
| void free_kthread_struct(struct task_struct *k) |
| { |
| struct kthread *kthread; |
| |
| /* |
| * Can be NULL if this kthread was created by kernel_thread() |
| * or if kmalloc() in kthread() failed. |
| */ |
| kthread = to_kthread(k); |
| #ifdef CONFIG_BLK_CGROUP |
| WARN_ON_ONCE(kthread && kthread->blkcg_css); |
| #endif |
| kfree(kthread); |
| } |
| |
| /** |
| * kthread_should_stop - should this kthread return now? |
| * |
| * When someone calls kthread_stop() on your kthread, it will be woken |
| * and this will return true. You should then return, and your return |
| * value will be passed through to kthread_stop(). |
| */ |
| bool kthread_should_stop(void) |
| { |
| return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags); |
| } |
| EXPORT_SYMBOL(kthread_should_stop); |
| |
| bool __kthread_should_park(struct task_struct *k) |
| { |
| return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(k)->flags); |
| } |
| EXPORT_SYMBOL_GPL(__kthread_should_park); |
| |
| /** |
| * kthread_should_park - should this kthread park now? |
| * |
| * When someone calls kthread_park() on your kthread, it will be woken |
| * and this will return true. You should then do the necessary |
| * cleanup and call kthread_parkme() |
| * |
| * Similar to kthread_should_stop(), but this keeps the thread alive |
| * and in a park position. kthread_unpark() "restarts" the thread and |
| * calls the thread function again. |
| */ |
| bool kthread_should_park(void) |
| { |
| return __kthread_should_park(current); |
| } |
| EXPORT_SYMBOL_GPL(kthread_should_park); |
| |
| /** |
| * kthread_freezable_should_stop - should this freezable kthread return now? |
| * @was_frozen: optional out parameter, indicates whether %current was frozen |
| * |
| * kthread_should_stop() for freezable kthreads, which will enter |
| * refrigerator if necessary. This function is safe from kthread_stop() / |
| * freezer deadlock and freezable kthreads should use this function instead |
| * of calling try_to_freeze() directly. |
| */ |
| bool kthread_freezable_should_stop(bool *was_frozen) |
| { |
| bool frozen = false; |
| |
| might_sleep(); |
| |
| if (unlikely(freezing(current))) |
| frozen = __refrigerator(true); |
| |
| if (was_frozen) |
| *was_frozen = frozen; |
| |
| return kthread_should_stop(); |
| } |
| 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) |
| { |
| struct kthread *kthread = __to_kthread(task); |
| if (kthread) |
| return kthread->threadfn; |
| return NULL; |
| } |
| EXPORT_SYMBOL_GPL(kthread_func); |
| |
| /** |
| * kthread_data - return data value specified on kthread creation |
| * @task: kthread task in question |
| * |
| * Return the data value specified when kthread @task was created. |
| * The caller is responsible for ensuring the validity of @task when |
| * calling this function. |
| */ |
| 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() |
| * @task: possible kthread task in question |
| * |
| * @task could be a kthread task. Return the data value specified when it |
| * was created if accessible. If @task isn't a kthread task or its data is |
| * inaccessible for any reason, %NULL is returned. This function requires |
| * that @task itself is safe to dereference. |
| */ |
| void *kthread_probe_data(struct task_struct *task) |
| { |
| struct kthread *kthread = __to_kthread(task); |
| void *data = NULL; |
| |
| if (kthread) |
| copy_from_kernel_nofault(&data, &kthread->data, sizeof(data)); |
| return data; |
| } |
| |
| static void __kthread_parkme(struct kthread *self) |
| { |
| for (;;) { |
| /* |
| * TASK_PARKED is a special state; we must serialize against |
| * possible pending wakeups to avoid store-store collisions on |
| * task->state. |
| * |
| * Such a collision might possibly result in the task state |
| * changin from TASK_PARKED and us failing the |
| * wait_task_inactive() in kthread_park(). |
| */ |
| set_special_state(TASK_PARKED); |
| 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_preempt_disabled(); |
| preempt_enable(); |
| } |
| __set_current_state(TASK_RUNNING); |
| } |
| |
| void kthread_parkme(void) |
| { |
| __kthread_parkme(to_kthread(current)); |
| } |
| EXPORT_SYMBOL_GPL(kthread_parkme); |
| |
| static int kthread(void *_create) |
| { |
| /* Copy data: it's on kthread's stack */ |
| struct kthread_create_info *create = _create; |
| int (*threadfn)(void *data) = create->threadfn; |
| void *data = create->data; |
| struct completion *done; |
| struct kthread *self; |
| int ret; |
| |
| self = kzalloc(sizeof(*self), GFP_KERNEL); |
| set_kthread_struct(self); |
| |
| /* If user was SIGKILLed, I release the structure. */ |
| done = xchg(&create->done, NULL); |
| if (!done) { |
| kfree(create); |
| do_exit(-EINTR); |
| } |
| |
| if (!self) { |
| create->result = ERR_PTR(-ENOMEM); |
| complete(done); |
| do_exit(-ENOMEM); |
| } |
| |
| self->threadfn = threadfn; |
| self->data = data; |
| init_completion(&self->exited); |
| init_completion(&self->parked); |
| current->vfork_done = &self->exited; |
| |
| /* 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_preempt_disabled(); |
| preempt_enable(); |
| |
| ret = -EINTR; |
| if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) { |
| cgroup_kthread_ready(); |
| __kthread_parkme(self); |
| ret = threadfn(data); |
| } |
| do_exit(ret); |
| } |
| |
| /* called from do_fork() to get node information for about to be created task */ |
| int tsk_fork_get_node(struct task_struct *tsk) |
| { |
| #ifdef CONFIG_NUMA |
| if (tsk == kthreadd_task) |
| return tsk->pref_node_fork; |
| #endif |
| return NUMA_NO_NODE; |
| } |
| |
| static void create_kthread(struct kthread_create_info *create) |
| { |
| int pid; |
| |
| #ifdef CONFIG_NUMA |
| current->pref_node_fork = create->node; |
| #endif |
| /* We want our own signal handler (we take no signals by default). */ |
| pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD); |
| if (pid < 0) { |
| /* If user was SIGKILLed, I release the structure. */ |
| struct completion *done = xchg(&create->done, NULL); |
| |
| if (!done) { |
| kfree(create); |
| return; |
| } |
| create->result = ERR_PTR(pid); |
| complete(done); |
| } |
| } |
| |
| static __printf(4, 0) |
| struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data), |
| void *data, int node, |
| const char namefmt[], |
| va_list args) |
| { |
| DECLARE_COMPLETION_ONSTACK(done); |
| struct task_struct *task; |
| struct kthread_create_info *create = kmalloc(sizeof(*create), |
| GFP_KERNEL); |
| |
| if (!create) |
| return ERR_PTR(-ENOMEM); |
| create->threadfn = threadfn; |
| create->data = data; |
| create->node = node; |
| create->done = &done; |
| |
| spin_lock(&kthread_create_lock); |
| list_add_tail(&create->list, &kthread_create_list); |
| spin_unlock(&kthread_create_lock); |
| |
| wake_up_process(kthreadd_task); |
| /* |
| * Wait for completion in killable state, for I might be chosen by |
| * the OOM killer while kthreadd is trying to allocate memory for |
| * new kernel thread. |
| */ |
| if (unlikely(wait_for_completion_killable(&done))) { |
| /* |
| * If I was SIGKILLed before kthreadd (or new kernel thread) |
| * calls complete(), leave the cleanup of this structure to |
| * that thread. |
| */ |
| if (xchg(&create->done, NULL)) |
| return ERR_PTR(-EINTR); |
| /* |
| * kthreadd (or new kernel thread) will call complete() |
| * shortly. |
| */ |
| wait_for_completion(&done); |
| } |
| task = create->result; |
| if (!IS_ERR(task)) { |
| static const struct sched_param param = { .sched_priority = 0 }; |
| char name[TASK_COMM_LEN]; |
| |
| /* |
| * task is already visible to other tasks, so updating |
| * COMM must be protected. |
| */ |
| vsnprintf(name, sizeof(name), namefmt, args); |
| set_task_comm(task, name); |
| /* |
| * root may have changed our (kthreadd's) priority or CPU mask. |
| * The kernel thread should not inherit these properties. |
| */ |
| sched_setscheduler_nocheck(task, SCHED_NORMAL, ¶m); |
| set_cpus_allowed_ptr(task, |
| housekeeping_cpumask(HK_FLAG_KTHREAD)); |
| } |
| kfree(create); |
| return task; |
| } |
| |
| /** |
| * kthread_create_on_node - create a kthread. |
| * @threadfn: the function to run until signal_pending(current). |
| * @data: data ptr for @threadfn. |
| * @node: task and thread structures for the thread are allocated on this node |
| * @namefmt: printf-style name for the thread. |
| * |
| * Description: This helper function creates and names a kernel |
| * thread. The thread will be stopped: use wake_up_process() to start |
| * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and |
| * is affine to all CPUs. |
| * |
| * If thread is going to be bound on a particular cpu, give its node |
| * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE. |
| * When woken, the thread will run @threadfn() with @data as its |
| * argument. @threadfn() can either call do_exit() directly if it is a |
| * standalone thread for which no one will call kthread_stop(), or |
| * return when 'kthread_should_stop()' is true (which means |
| * kthread_stop() has been called). The return value should be zero |
| * or a negative error number; it will be passed to kthread_stop(). |
| * |
| * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR). |
| */ |
| struct task_struct *kthread_create_on_node(int (*threadfn)(void *data), |
| void *data, int node, |
| const char namefmt[], |
| ...) |
| { |
| struct task_struct *task; |
| va_list args; |
| |
| va_start(args, namefmt); |
| task = __kthread_create_on_node(threadfn, data, node, namefmt, args); |
| va_end(args); |
| |
| return task; |
| } |
| EXPORT_SYMBOL(kthread_create_on_node); |
| |
| static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, long state) |
| { |
| unsigned long flags; |
| |
| if (!wait_task_inactive(p, state)) { |
| WARN_ON(1); |
| return; |
| } |
| |
| /* It's safe because the task is inactive. */ |
| raw_spin_lock_irqsave(&p->pi_lock, flags); |
| do_set_cpus_allowed(p, mask); |
| p->flags |= PF_NO_SETAFFINITY; |
| raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
| } |
| |
| static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state) |
| { |
| __kthread_bind_mask(p, cpumask_of(cpu), state); |
| } |
| |
| void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask) |
| { |
| __kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE); |
| } |
| EXPORT_SYMBOL_GPL(kthread_bind_mask); |
| |
| /** |
| * kthread_bind - bind a just-created kthread to a cpu. |
| * @p: thread created by kthread_create(). |
| * @cpu: cpu (might not be online, must be possible) for @k to run on. |
| * |
| * Description: This function is equivalent to set_cpus_allowed(), |
| * except that @cpu doesn't need to be online, and the thread must be |
| * stopped (i.e., just returned from kthread_create()). |
| */ |
| void kthread_bind(struct task_struct *p, unsigned int cpu) |
| { |
| __kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE); |
| } |
| EXPORT_SYMBOL(kthread_bind); |
| |
| /** |
| * kthread_create_on_cpu - Create a cpu bound kthread |
| * @threadfn: the function to run until signal_pending(current). |
| * @data: data ptr for @threadfn. |
| * @cpu: The cpu on which the thread should be bound, |
| * @namefmt: printf-style name for the thread. Format is restricted |
| * to "name.*%u". Code fills in cpu number. |
| * |
| * Description: This helper function creates and names a kernel thread |
| */ |
| struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), |
| void *data, unsigned int cpu, |
| const char *namefmt) |
| { |
| struct task_struct *p; |
| |
| p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt, |
| cpu); |
| if (IS_ERR(p)) |
| return p; |
| kthread_bind(p, cpu); |
| /* CPU hotplug need to bind once again when unparking the thread. */ |
| to_kthread(p)->cpu = cpu; |
| return p; |
| } |
| EXPORT_SYMBOL(kthread_create_on_cpu); |
| |
| void kthread_set_per_cpu(struct task_struct *k, int cpu) |
| { |
| struct kthread *kthread = to_kthread(k); |
| if (!kthread) |
| return; |
| |
| WARN_ON_ONCE(!(k->flags & PF_NO_SETAFFINITY)); |
| |
| if (cpu < 0) { |
| clear_bit(KTHREAD_IS_PER_CPU, &kthread->flags); |
| return; |
| } |
| |
| kthread->cpu = cpu; |
| set_bit(KTHREAD_IS_PER_CPU, &kthread->flags); |
| } |
| EXPORT_SYMBOL_GPL(kthread_set_per_cpu); |
| |
| bool kthread_is_per_cpu(struct task_struct *p) |
| { |
| struct kthread *kthread = __to_kthread(p); |
| if (!kthread) |
| return false; |
| |
| return test_bit(KTHREAD_IS_PER_CPU, &kthread->flags); |
| } |
| |
| /** |
| * kthread_unpark - unpark a thread created by kthread_create(). |
| * @k: thread created by kthread_create(). |
| * |
| * Sets kthread_should_park() for @k to return false, wakes it, and |
| * waits for it to return. If the thread is marked percpu then its |
| * bound to the cpu again. |
| */ |
| void kthread_unpark(struct task_struct *k) |
| { |
| struct kthread *kthread = to_kthread(k); |
| |
| /* |
| * Newly created kthread was parked when the CPU was offline. |
| * The binding was lost and we need to set it again. |
| */ |
| if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags)) |
| __kthread_bind(k, kthread->cpu, TASK_PARKED); |
| |
| clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags); |
| /* |
| * __kthread_parkme() will either see !SHOULD_PARK or get the wakeup. |
| */ |
| wake_up_state(k, TASK_PARKED); |
| } |
| EXPORT_SYMBOL_GPL(kthread_unpark); |
| |
| /** |
| * kthread_park - park a thread created by kthread_create(). |
| * @k: thread created by kthread_create(). |
| * |
| * Sets kthread_should_park() for @k to return true, wakes it, and |
| * waits for it to return. This can also be called after kthread_create() |
| * instead of calling wake_up_process(): the thread will park without |
| * calling threadfn(). |
| * |
| * Returns 0 if the thread is parked, -ENOSYS if the thread exited. |
| * If called by the kthread itself just the park bit is set. |
| */ |
| int kthread_park(struct task_struct *k) |
| { |
| 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, housekeeping_cpumask(HK_FLAG_KTHREAD)); |
| 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 |
| * 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); |
| if (!work->canceling) |
| 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; |
| |
| /* |
| * With CFI, timer->function can point to a jump table entry in a module, |
| * which fails the comparison. Disable the warning if CFI and modules are |
| * both enabled. |
| */ |
| if (!IS_ENABLED(CONFIG_CFI_CLANG) || !IS_ENABLED(CONFIG_MODULES)) |
| 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); |
| |
| /* |
| * Make sure that the timer is neither set nor running and could |
| * not manipulate the work list_head any longer. |
| * |
| * The function is called under worker->lock. The lock is temporary |
| * released but the timer can't be set again in the meantime. |
| */ |
| static void kthread_cancel_delayed_work_timer(struct kthread_work *work, |
| unsigned long *flags) |
| { |
| 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--; |
| } |
| |
| /* |
| * This function removes the work from the worker queue. |
| * |
| * It is called under worker->lock. The caller must make sure that |
| * the timer used by delayed work is not running, e.g. by calling |
| * kthread_cancel_delayed_work_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) |
| { |
| /* |
| * 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: %false if @dwork was idle and queued, %true 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 %true here. The return value can be used for reference |
| * counting and the number of queued works stays the same. Anyway, 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; |
| |
| raw_spin_lock_irqsave(&worker->lock, flags); |
| |
| /* Do not bother with canceling when never queued. */ |
| if (!work->worker) { |
| ret = false; |
| goto fast_queue; |
| } |
| |
| /* Work must not be used with >1 worker, see kthread_queue_work() */ |
| WARN_ON_ONCE(work->worker != worker); |
| |
| /* |
| * Temporary cancel the work but do not fight with another command |
| * that is canceling the work as well. |
| * |
| * It is a bit tricky because of possible races with another |
| * mod_delayed_work() and cancel_delayed_work() callers. |
| * |
| * The timer must be canceled first because worker->lock is released |
| * when doing so. But the work can be removed from the queue (list) |
| * only when it can be queued again so that the return value can |
| * be used for reference counting. |
| */ |
| kthread_cancel_delayed_work_timer(work, &flags); |
| if (work->canceling) { |
| /* The number of works in the queue does not change. */ |
| ret = true; |
| goto out; |
| } |
| ret = __kthread_cancel_work(work); |
| |
| /* |
| * Canceling could run in parallel from kthread_cancel_delayed_work_sync |
| * and change work's canceling count as the spinlock is released and regain |
| * in __kthread_cancel_work so we need to check the count again. Otherwise, |
| * we might incorrectly queue the dwork and further cause |
| * cancel_delayed_work_sync thread waiting for flush dwork endlessly. |
| */ |
| if (work->canceling) { |
| ret = false; |
| goto out; |
| } |
| |
| 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); |
| |
| if (is_dwork) |
| kthread_cancel_delayed_work_timer(work, &flags); |
| |
| ret = __kthread_cancel_work(work); |
| |
| 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); |
| |
| /** |
| * 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 |
| * @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 |