linux/lib/lwq.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Light-weight single-linked queue.
 *
 * Entries are enqueued to the head of an llist, with no blocking.
 * This can happen in any context.
 *
 * Entries are dequeued using a spinlock to protect against multiple
 * access.  The llist is staged in reverse order, and refreshed
 * from the llist when it exhausts.
 *
 * This is particularly suitable when work items are queued in BH or
 * IRQ context, and where work items are handled one at a time by
 * dedicated threads.
 */
#include <linux/rcupdate.h>
#include <linux/lwq.h>

struct llist_node *__lwq_dequeue(struct lwq *q)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * lwq_dequeue_all - dequeue all currently enqueued objects
 * @q:	the queue to dequeue from
 *
 * Remove and return a linked list of llist_nodes of all the objects that were
 * in the queue. The first on the list will be the object that was least
 * recently enqueued.
 */
struct llist_node *lwq_dequeue_all(struct lwq *q)
{ … }
EXPORT_SYMBOL_GPL(…);

#if IS_ENABLED(CONFIG_LWQ_TEST)

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/wait_bit.h>
#include <linux/kthread.h>
#include <linux/delay.h>
struct tnode { … };

static int lwq_exercise(void *qv)
{ … }

static int lwq_test(void)
{ … }

module_init(…) …;
#endif /* CONFIG_LWQ_TEST*/