lib/klist.c

Source file repositories/reference/linux-study-clean/lib/klist.c

File Facts

System
Linux kernel
Corpus path
lib/klist.c
Extension
.c
Size
10680 bytes
Lines
408
Domain
Kernel Services
Bucket
lib
Inferred role
Kernel Services: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Shared kernel service surface used by multiple subsystems, including helpers, cryptography, virtualization support, and async I/O infrastructure.

Dependency Surface

Detected Declarations

Annotated Snippet

struct klist_waiter {
	struct list_head list;
	struct klist_node *node;
	struct task_struct *process;
	int woken;
};

static DEFINE_SPINLOCK(klist_remove_lock);
static LIST_HEAD(klist_remove_waiters);

static void klist_release(struct kref *kref)
{
	struct klist_waiter *waiter, *tmp;
	struct klist_node *n = container_of(kref, struct klist_node, n_ref);

	WARN_ON(!knode_dead(n));
	list_del(&n->n_node);
	spin_lock(&klist_remove_lock);
	list_for_each_entry_safe(waiter, tmp, &klist_remove_waiters, list) {
		if (waiter->node != n)
			continue;

		list_del(&waiter->list);
		waiter->woken = 1;
		mb();
		wake_up_process(waiter->process);
	}
	spin_unlock(&klist_remove_lock);
	knode_set_klist(n, NULL);
}

static int klist_dec_and_del(struct klist_node *n)
{
	return kref_put(&n->n_ref, klist_release);
}

static void klist_put(struct klist_node *n, bool kill)
{
	struct klist *k = knode_klist(n);
	void (*put)(struct klist_node *) = k->put;

	spin_lock(&k->k_lock);
	if (kill)
		knode_kill(n);
	if (!klist_dec_and_del(n))
		put = NULL;
	spin_unlock(&k->k_lock);
	if (put)
		put(n);
}

/**
 * klist_del - Decrement the reference count of node and try to remove.
 * @n: node we're deleting.
 */
void klist_del(struct klist_node *n)
{
	klist_put(n, true);
}
EXPORT_SYMBOL_GPL(klist_del);

/**
 * klist_remove - Decrement the refcount of node and wait for it to go away.
 * @n: node we're removing.
 */
void klist_remove(struct klist_node *n)
{
	struct klist_waiter waiter;

	waiter.node = n;
	waiter.process = current;
	waiter.woken = 0;
	spin_lock(&klist_remove_lock);
	list_add(&waiter.list, &klist_remove_waiters);
	spin_unlock(&klist_remove_lock);

	klist_del(n);

	for (;;) {
		set_current_state(TASK_UNINTERRUPTIBLE);
		if (waiter.woken)
			break;
		schedule();
	}
	__set_current_state(TASK_RUNNING);
}
EXPORT_SYMBOL_GPL(klist_remove);

/**
 * klist_node_attached - Say whether a node is bound to a list or not.

Annotation

Implementation Notes