linux/fs/io-wq.h

#ifndef INTERNAL_IO_WQ_H
#define INTERNAL_IO_WQ_H

#include <linux/refcount.h>

struct io_wq;

enum {
	IO_WQ_WORK_CANCEL	= 1,
	IO_WQ_WORK_HASHED	= 2,
	IO_WQ_WORK_UNBOUND	= 4,
	IO_WQ_WORK_CONCURRENT	= 16,

	IO_WQ_HASH_SHIFT	= 24,	/* upper 8 bits are used for hash key */
};

enum io_wq_cancel {
	IO_WQ_CANCEL_OK,	/* cancelled before started */
	IO_WQ_CANCEL_RUNNING,	/* found, running, and attempted cancelled */
	IO_WQ_CANCEL_NOTFOUND,	/* work not found */
};

struct io_wq_work_node {
	struct io_wq_work_node *next;
};

struct io_wq_work_list {
	struct io_wq_work_node *first;
	struct io_wq_work_node *last;
};

#define wq_list_for_each(pos, prv, head)			\
	for (pos = (head)->first, prv = NULL; pos; prv = pos, pos = (pos)->next)

#define wq_list_for_each_resume(pos, prv)			\
	for (; pos; prv = pos, pos = (pos)->next)

#define wq_list_empty(list)	(READ_ONCE((list)->first) == NULL)
#define INIT_WQ_LIST(list)	do {				\
	(list)->first = NULL;					\
} while (0)

static inline void wq_list_add_after(struct io_wq_work_node *node,
				     struct io_wq_work_node *pos,
				     struct io_wq_work_list *list)
{
	struct io_wq_work_node *next = pos->next;

	pos->next = node;
	node->next = next;
	if (!next)
		list->last = node;
}

/**
 * wq_list_merge - merge the second list to the first one.
 * @list0: the first list
 * @list1: the second list
 * Return the first node after mergence.
 */
static inline struct io_wq_work_node *wq_list_merge(struct io_wq_work_list *list0,
						    struct io_wq_work_list *list1)
{
	struct io_wq_work_node *ret;

	if (!list0->first) {
		ret = list1->first;
	} else {
		ret = list0->first;
		list0->last->next = list1->first;
	}
	INIT_WQ_LIST(list0);
	INIT_WQ_LIST(list1);
	return ret;
}

static inline void wq_list_add_tail(struct io_wq_work_node *node,
				    struct io_wq_work_list *list)
{
	node->next = NULL;
	if (!list->first) {
		list->last = node;
		WRITE_ONCE(list->first, node);
	} else {
		list->last->next = node;
		list->last = node;
	}
}

static inline void wq_list_add_head(struct io_wq_work_node *node,
				    struct io_wq_work_list *list)
{
	node->next = list->first;
	if (!node->next)
		list->last = node;
	WRITE_ONCE(list->first, node);
}

static inline void wq_list_cut(struct io_wq_work_list *list,
			       struct io_wq_work_node *last,
			       struct io_wq_work_node *prev)
{
	/* first in the list, if prev==NULL */
	if (!prev)
		WRITE_ONCE(list->first, last->next);
	else
		prev->next = last->next;

	if (last == list->last)
		list->last = prev;
	last->next = NULL;
}

static inline void __wq_list_splice(struct io_wq_work_list *list,
				    struct io_wq_work_node *to)
{
	list->last->next = to->next;
	to->next = list->first;
	INIT_WQ_LIST(list);
}

static inline bool wq_list_splice(struct io_wq_work_list *list,
				  struct io_wq_work_node *to)
{
	if (!wq_list_empty(list)) {
		__wq_list_splice(list, to);
		return true;
	}
	return false;
}

static inline void wq_stack_add_head(struct io_wq_work_node *node,
				     struct io_wq_work_node *stack)
{
	node->next = stack->next;
	stack->next = node;
}

static inline void wq_list_del(struct io_wq_work_list *list,
			       struct io_wq_work_node *node,
			       struct io_wq_work_node *prev)
{
	wq_list_cut(list, node, prev);
}

static inline
struct io_wq_work_node *wq_stack_extract(struct io_wq_work_node *stack)
{
	struct io_wq_work_node *node = stack->next;

	stack->next = node->next;
	return node;
}

struct io_wq_work {
	struct io_wq_work_node list;
	unsigned flags;
};

static inline struct io_wq_work *wq_next_work(struct io_wq_work *work)
{
	if (!work->list.next)
		return NULL;

	return container_of(work->list.next, struct io_wq_work, list);
}

typedef struct io_wq_work *(free_work_fn)(struct io_wq_work *);
typedef void (io_wq_work_fn)(struct io_wq_work *);

struct io_wq_hash {
	refcount_t refs;
	unsigned long map;
	struct wait_queue_head wait;
};

static inline void io_wq_put_hash(struct io_wq_hash *hash)
{
	if (refcount_dec_and_test(&hash->refs))
		kfree(hash);
}

struct io_wq_data {
	struct io_wq_hash *hash;
	struct task_struct *task;
	io_wq_work_fn *do_work;
	free_work_fn *free_work;
};

struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data);
void io_wq_exit_start(struct io_wq *wq);
void io_wq_put_and_exit(struct io_wq *wq);

void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work);
void io_wq_hash_work(struct io_wq_work *work, void *val);

int io_wq_cpu_affinity(struct io_wq *wq, cpumask_var_t mask);
int io_wq_max_workers(struct io_wq *wq, int *new_count);

static inline bool io_wq_is_hashed(struct io_wq_work *work)
{
	return work->flags & IO_WQ_WORK_HASHED;
}

typedef bool (work_cancel_fn)(struct io_wq_work *, void *);

enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
					void *data, bool cancel_all);

#if defined(CONFIG_IO_WQ)
extern void io_wq_worker_sleeping(struct task_struct *);
extern void io_wq_worker_running(struct task_struct *);
#else
static inline void io_wq_worker_sleeping(struct task_struct *tsk)
{
}
static inline void io_wq_worker_running(struct task_struct *tsk)
{
}
#endif

static inline bool io_wq_current_is_worker(void)
{
	return in_task() && (current->flags & PF_IO_WORKER) &&
		current->worker_private;
}
#endif