46f3d97621
kthread_worker provides minimalistic workqueue-like interface for users which need a dedicated worker thread (e.g. for realtime priority). It has basic queue, flush_work, flush_worker operations which mostly match the workqueue counterparts; however, due to the way flush_work() is implemented, it has a noticeable difference of not allowing work items to be freed while being executed. While the current users of kthread_worker are okay with the current behavior, the restriction does impede some valid use cases. Also, removing this difference isn't difficult and actually makes the code easier to understand. This patch reimplements flush_kthread_work() such that it uses a flush_work item instead of queue/done sequence numbers. Signed-off-by: Tejun Heo <tj@kernel.org>
131 lines
4.1 KiB
C
131 lines
4.1 KiB
C
#ifndef _LINUX_KTHREAD_H
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#define _LINUX_KTHREAD_H
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/* Simple interface for creating and stopping kernel threads without mess. */
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#include <linux/err.h>
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#include <linux/sched.h>
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__printf(4, 5)
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struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
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void *data,
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int node,
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const char namefmt[], ...);
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#define kthread_create(threadfn, data, namefmt, arg...) \
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kthread_create_on_node(threadfn, data, -1, namefmt, ##arg)
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/**
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* kthread_run - create and wake a thread.
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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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* @namefmt: printf-style name for the thread.
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*
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* Description: Convenient wrapper for kthread_create() followed by
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* wake_up_process(). Returns the kthread or ERR_PTR(-ENOMEM).
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*/
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#define kthread_run(threadfn, data, namefmt, ...) \
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({ \
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struct task_struct *__k \
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= kthread_create(threadfn, data, namefmt, ## __VA_ARGS__); \
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if (!IS_ERR(__k)) \
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wake_up_process(__k); \
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__k; \
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})
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void kthread_bind(struct task_struct *k, unsigned int cpu);
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int kthread_stop(struct task_struct *k);
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int kthread_should_stop(void);
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bool kthread_freezable_should_stop(bool *was_frozen);
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void *kthread_data(struct task_struct *k);
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int kthreadd(void *unused);
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extern struct task_struct *kthreadd_task;
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extern int tsk_fork_get_node(struct task_struct *tsk);
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/*
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* Simple work processor based on kthread.
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*
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* This provides easier way to make use of kthreads. A kthread_work
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* can be queued and flushed using queue/flush_kthread_work()
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* respectively. Queued kthread_works are processed by a kthread
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* running kthread_worker_fn().
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*/
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struct kthread_work;
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typedef void (*kthread_work_func_t)(struct kthread_work *work);
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struct kthread_worker {
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spinlock_t lock;
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struct list_head work_list;
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struct task_struct *task;
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struct kthread_work *current_work;
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};
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struct kthread_work {
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struct list_head node;
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kthread_work_func_t func;
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wait_queue_head_t done;
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struct kthread_worker *worker;
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};
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#define KTHREAD_WORKER_INIT(worker) { \
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.lock = __SPIN_LOCK_UNLOCKED((worker).lock), \
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.work_list = LIST_HEAD_INIT((worker).work_list), \
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}
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#define KTHREAD_WORK_INIT(work, fn) { \
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.node = LIST_HEAD_INIT((work).node), \
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.func = (fn), \
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.done = __WAIT_QUEUE_HEAD_INITIALIZER((work).done), \
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}
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#define DEFINE_KTHREAD_WORKER(worker) \
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struct kthread_worker worker = KTHREAD_WORKER_INIT(worker)
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#define DEFINE_KTHREAD_WORK(work, fn) \
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struct kthread_work work = KTHREAD_WORK_INIT(work, fn)
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/*
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* kthread_worker.lock and kthread_work.done need their own lockdep class
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* keys if they are defined on stack with lockdep enabled. Use the
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* following macros when defining them on stack.
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*/
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#ifdef CONFIG_LOCKDEP
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# define KTHREAD_WORKER_INIT_ONSTACK(worker) \
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({ init_kthread_worker(&worker); worker; })
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# define DEFINE_KTHREAD_WORKER_ONSTACK(worker) \
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struct kthread_worker worker = KTHREAD_WORKER_INIT_ONSTACK(worker)
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# define KTHREAD_WORK_INIT_ONSTACK(work, fn) \
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({ init_kthread_work((&work), fn); work; })
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# define DEFINE_KTHREAD_WORK_ONSTACK(work, fn) \
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struct kthread_work work = KTHREAD_WORK_INIT_ONSTACK(work, fn)
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#else
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# define DEFINE_KTHREAD_WORKER_ONSTACK(worker) DEFINE_KTHREAD_WORKER(worker)
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# define DEFINE_KTHREAD_WORK_ONSTACK(work, fn) DEFINE_KTHREAD_WORK(work, fn)
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#endif
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extern void __init_kthread_worker(struct kthread_worker *worker,
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const char *name, struct lock_class_key *key);
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#define init_kthread_worker(worker) \
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do { \
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static struct lock_class_key __key; \
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__init_kthread_worker((worker), "("#worker")->lock", &__key); \
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} while (0)
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#define init_kthread_work(work, fn) \
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do { \
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memset((work), 0, sizeof(struct kthread_work)); \
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INIT_LIST_HEAD(&(work)->node); \
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(work)->func = (fn); \
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init_waitqueue_head(&(work)->done); \
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} while (0)
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int kthread_worker_fn(void *worker_ptr);
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bool queue_kthread_work(struct kthread_worker *worker,
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struct kthread_work *work);
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void flush_kthread_work(struct kthread_work *work);
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void flush_kthread_worker(struct kthread_worker *worker);
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#endif /* _LINUX_KTHREAD_H */
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