devres: Clarify documentation for devres_destroy()

[deliverable/linux.git] / drivers / base / devres.c

/*
 * drivers/base/devres.c - device resource management
 *
 * Copyright (c) 2006  SUSE Linux Products GmbH
 * Copyright (c) 2006  Tejun Heo <teheo@suse.de>
 *
 * This file is released under the GPLv2.
 */

#include <linux/device.h>
#include <linux/module.h>
#include <linux/slab.h>

#include "base.h"

struct devres_node {
	struct list_head		entry;
	dr_release_t			release;
#ifdef CONFIG_DEBUG_DEVRES
	const char			*name;
	size_t				size;
#endif
};

struct devres {
	struct devres_node		node;
	/* -- 3 pointers */
	unsigned long long		data[];	/* guarantee ull alignment */
};

struct devres_group {
	struct devres_node		node[2];
	void				*id;
	int				color;
	/* -- 8 pointers */
};

#ifdef CONFIG_DEBUG_DEVRES
static int log_devres = 0;
module_param_named(log, log_devres, int, S_IRUGO | S_IWUSR);

static void set_node_dbginfo(struct devres_node *node, const char *name,
			     size_t size)
{
	node->name = name;
	node->size = size;
}

static void devres_log(struct device *dev, struct devres_node *node,
		       const char *op)
{
	if (unlikely(log_devres))
		dev_printk(KERN_ERR, dev, "DEVRES %3s %p %s (%lu bytes)\n",
			   op, node, node->name, (unsigned long)node->size);
}
#else /* CONFIG_DEBUG_DEVRES */
#define set_node_dbginfo(node, n, s)	do {} while (0)
#define devres_log(dev, node, op)	do {} while (0)
#endif /* CONFIG_DEBUG_DEVRES */

/*
 * Release functions for devres group.  These callbacks are used only
 * for identification.
 */
static void group_open_release(struct device *dev, void *res)
{
	/* noop */
}

static void group_close_release(struct device *dev, void *res)
{
	/* noop */
}

static struct devres_group * node_to_group(struct devres_node *node)
{
	if (node->release == &group_open_release)
		return container_of(node, struct devres_group, node[0]);
	if (node->release == &group_close_release)
		return container_of(node, struct devres_group, node[1]);
	return NULL;
}

static __always_inline struct devres * alloc_dr(dr_release_t release,
						size_t size, gfp_t gfp)
{
	size_t tot_size = sizeof(struct devres) + size;
	struct devres *dr;

	dr = kmalloc_track_caller(tot_size, gfp);
	if (unlikely(!dr))
		return NULL;

	memset(dr, 0, tot_size);
	INIT_LIST_HEAD(&dr->node.entry);
	dr->node.release = release;
	return dr;
}

static void add_dr(struct device *dev, struct devres_node *node)
{
	devres_log(dev, node, "ADD");
	BUG_ON(!list_empty(&node->entry));
	list_add_tail(&node->entry, &dev->devres_head);
}

#ifdef CONFIG_DEBUG_DEVRES
void * __devres_alloc(dr_release_t release, size_t size, gfp_t gfp,
		      const char *name)
{
	struct devres *dr;

	dr = alloc_dr(release, size, gfp);
	if (unlikely(!dr))
		return NULL;
	set_node_dbginfo(&dr->node, name, size);
	return dr->data;
}
EXPORT_SYMBOL_GPL(__devres_alloc);
#else
/**
 * devres_alloc - Allocate device resource data
 * @release: Release function devres will be associated with
 * @size: Allocation size
 * @gfp: Allocation flags
 *
 * Allocate devres of @size bytes.  The allocated area is zeroed, then
 * associated with @release.  The returned pointer can be passed to
 * other devres_*() functions.
 *
 * RETURNS:
 * Pointer to allocated devres on success, NULL on failure.
 */
void * devres_alloc(dr_release_t release, size_t size, gfp_t gfp)
{
	struct devres *dr;

	dr = alloc_dr(release, size, gfp);
	if (unlikely(!dr))
		return NULL;
	return dr->data;
}
EXPORT_SYMBOL_GPL(devres_alloc);
#endif

/**
 * devres_free - Free device resource data
 * @res: Pointer to devres data to free
 *
 * Free devres created with devres_alloc().
 */
void devres_free(void *res)
{
	if (res) {
		struct devres *dr = container_of(res, struct devres, data);

		BUG_ON(!list_empty(&dr->node.entry));
		kfree(dr);
	}
}
EXPORT_SYMBOL_GPL(devres_free);

/**
 * devres_add - Register device resource
 * @dev: Device to add resource to
 * @res: Resource to register
 *
 * Register devres @res to @dev.  @res should have been allocated
 * using devres_alloc().  On driver detach, the associated release
 * function will be invoked and devres will be freed automatically.
 */
void devres_add(struct device *dev, void *res)
{
	struct devres *dr = container_of(res, struct devres, data);
	unsigned long flags;

	spin_lock_irqsave(&dev->devres_lock, flags);
	add_dr(dev, &dr->node);
	spin_unlock_irqrestore(&dev->devres_lock, flags);
}
EXPORT_SYMBOL_GPL(devres_add);

static struct devres *find_dr(struct device *dev, dr_release_t release,
			      dr_match_t match, void *match_data)
{
	struct devres_node *node;

	list_for_each_entry_reverse(node, &dev->devres_head, entry) {
		struct devres *dr = container_of(node, struct devres, node);

		if (node->release != release)
			continue;
		if (match && !match(dev, dr->data, match_data))
			continue;
		return dr;
	}

	return NULL;
}

/**
 * devres_find - Find device resource
 * @dev: Device to lookup resource from
 * @release: Look for resources associated with this release function
 * @match: Match function (optional)
 * @match_data: Data for the match function
 *
 * Find the latest devres of @dev which is associated with @release
 * and for which @match returns 1.  If @match is NULL, it's considered
 * to match all.
 *
 * RETURNS:
 * Pointer to found devres, NULL if not found.
 */
void * devres_find(struct device *dev, dr_release_t release,
		   dr_match_t match, void *match_data)
{
	struct devres *dr;
	unsigned long flags;

	spin_lock_irqsave(&dev->devres_lock, flags);
	dr = find_dr(dev, release, match, match_data);
	spin_unlock_irqrestore(&dev->devres_lock, flags);

	if (dr)
		return dr->data;
	return NULL;
}
EXPORT_SYMBOL_GPL(devres_find);

/**
 * devres_get - Find devres, if non-existent, add one atomically
 * @dev: Device to lookup or add devres for
 * @new_res: Pointer to new initialized devres to add if not found
 * @match: Match function (optional)
 * @match_data: Data for the match function
 *
 * Find the latest devres of @dev which has the same release function
 * as @new_res and for which @match return 1.  If found, @new_res is
 * freed; otherwise, @new_res is added atomically.
 *
 * RETURNS:
 * Pointer to found or added devres.
 */
void * devres_get(struct device *dev, void *new_res,
		  dr_match_t match, void *match_data)
{
	struct devres *new_dr = container_of(new_res, struct devres, data);
	struct devres *dr;
	unsigned long flags;

	spin_lock_irqsave(&dev->devres_lock, flags);
	dr = find_dr(dev, new_dr->node.release, match, match_data);
	if (!dr) {
		add_dr(dev, &new_dr->node);
		dr = new_dr;
		new_dr = NULL;
	}
	spin_unlock_irqrestore(&dev->devres_lock, flags);
	devres_free(new_dr);

	return dr->data;
}
EXPORT_SYMBOL_GPL(devres_get);

/**
 * devres_remove - Find a device resource and remove it
 * @dev: Device to find resource from
 * @release: Look for resources associated with this release function
 * @match: Match function (optional)
 * @match_data: Data for the match function
 *
 * Find the latest devres of @dev associated with @release and for
 * which @match returns 1.  If @match is NULL, it's considered to
 * match all.  If found, the resource is removed atomically and
 * returned.
 *
 * RETURNS:
 * Pointer to removed devres on success, NULL if not found.
 */
void * devres_remove(struct device *dev, dr_release_t release,
		     dr_match_t match, void *match_data)
{
	struct devres *dr;
	unsigned long flags;

	spin_lock_irqsave(&dev->devres_lock, flags);
	dr = find_dr(dev, release, match, match_data);
	if (dr) {
		list_del_init(&dr->node.entry);
		devres_log(dev, &dr->node, "REM");
	}
	spin_unlock_irqrestore(&dev->devres_lock, flags);

	if (dr)
		return dr->data;
	return NULL;
}
EXPORT_SYMBOL_GPL(devres_remove);

/**
 * devres_destroy - Find a device resource and destroy it
 * @dev: Device to find resource from
 * @release: Look for resources associated with this release function
 * @match: Match function (optional)
 * @match_data: Data for the match function
 *
 * Find the latest devres of @dev associated with @release and for
 * which @match returns 1.  If @match is NULL, it's considered to
 * match all.  If found, the resource is removed atomically and freed.
 *
 * Note that the release function for the resource will not be called,
 * only the devres-allocated data will be freed.  The caller becomes
 * responsible for freeing any other data.
 *
 * RETURNS:
 * 0 if devres is found and freed, -ENOENT if not found.
 */
int devres_destroy(struct device *dev, dr_release_t release,
		   dr_match_t match, void *match_data)
{
	void *res;

	res = devres_remove(dev, release, match, match_data);
	if (unlikely(!res))
		return -ENOENT;

	devres_free(res);
	return 0;
}
EXPORT_SYMBOL_GPL(devres_destroy);

static int remove_nodes(struct device *dev,
			struct list_head *first, struct list_head *end,
			struct list_head *todo)
{
	int cnt = 0, nr_groups = 0;
	struct list_head *cur;

	/* First pass - move normal devres entries to @todo and clear
	 * devres_group colors.
	 */
	cur = first;
	while (cur != end) {
		struct devres_node *node;
		struct devres_group *grp;

		node = list_entry(cur, struct devres_node, entry);
		cur = cur->next;

		grp = node_to_group(node);
		if (grp) {
			/* clear color of group markers in the first pass */
			grp->color = 0;
			nr_groups++;
		} else {
			/* regular devres entry */
			if (&node->entry == first)
				first = first->next;
			list_move_tail(&node->entry, todo);
			cnt++;
		}
	}

	if (!nr_groups)
		return cnt;

	/* Second pass - Scan groups and color them.  A group gets
	 * color value of two iff the group is wholly contained in
	 * [cur, end).  That is, for a closed group, both opening and
	 * closing markers should be in the range, while just the
	 * opening marker is enough for an open group.
	 */
	cur = first;
	while (cur != end) {
		struct devres_node *node;
		struct devres_group *grp;

		node = list_entry(cur, struct devres_node, entry);
		cur = cur->next;

		grp = node_to_group(node);
		BUG_ON(!grp || list_empty(&grp->node[0].entry));

		grp->color++;
		if (list_empty(&grp->node[1].entry))
			grp->color++;

		BUG_ON(grp->color <= 0 || grp->color > 2);
		if (grp->color == 2) {
			/* No need to update cur or end.  The removed
			 * nodes are always before both.
			 */
			list_move_tail(&grp->node[0].entry, todo);
			list_del_init(&grp->node[1].entry);
		}
	}

	return cnt;
}

static int release_nodes(struct device *dev, struct list_head *first,
			 struct list_head *end, unsigned long flags)
	__releases(&dev->devres_lock)
{
	LIST_HEAD(todo);
	int cnt;
	struct devres *dr, *tmp;

	cnt = remove_nodes(dev, first, end, &todo);

	spin_unlock_irqrestore(&dev->devres_lock, flags);

	/* Release.  Note that both devres and devres_group are
	 * handled as devres in the following loop.  This is safe.
	 */
	list_for_each_entry_safe_reverse(dr, tmp, &todo, node.entry) {
		devres_log(dev, &dr->node, "REL");
		dr->node.release(dev, dr->data);
		kfree(dr);
	}

	return cnt;
}

/**
 * devres_release_all - Release all managed resources
 * @dev: Device to release resources for
 *
 * Release all resources associated with @dev.  This function is
 * called on driver detach.
 */
int devres_release_all(struct device *dev)
{
	unsigned long flags;

	/* Looks like an uninitialized device structure */
	if (WARN_ON(dev->devres_head.next == NULL))
		return -ENODEV;
	spin_lock_irqsave(&dev->devres_lock, flags);
	return release_nodes(dev, dev->devres_head.next, &dev->devres_head,
			     flags);
}

/**
 * devres_open_group - Open a new devres group
 * @dev: Device to open devres group for
 * @id: Separator ID
 * @gfp: Allocation flags
 *
 * Open a new devres group for @dev with @id.  For @id, using a
 * pointer to an object which won't be used for another group is
 * recommended.  If @id is NULL, address-wise unique ID is created.
 *
 * RETURNS:
 * ID of the new group, NULL on failure.
 */
void * devres_open_group(struct device *dev, void *id, gfp_t gfp)
{
	struct devres_group *grp;
	unsigned long flags;

	grp = kmalloc(sizeof(*grp), gfp);
	if (unlikely(!grp))
		return NULL;

	grp->node[0].release = &group_open_release;
	grp->node[1].release = &group_close_release;
	INIT_LIST_HEAD(&grp->node[0].entry);
	INIT_LIST_HEAD(&grp->node[1].entry);
	set_node_dbginfo(&grp->node[0], "grp<", 0);
	set_node_dbginfo(&grp->node[1], "grp>", 0);
	grp->id = grp;
	if (id)
		grp->id = id;

	spin_lock_irqsave(&dev->devres_lock, flags);
	add_dr(dev, &grp->node[0]);
	spin_unlock_irqrestore(&dev->devres_lock, flags);
	return grp->id;
}
EXPORT_SYMBOL_GPL(devres_open_group);

/* Find devres group with ID @id.  If @id is NULL, look for the latest. */
static struct devres_group * find_group(struct device *dev, void *id)
{
	struct devres_node *node;

	list_for_each_entry_reverse(node, &dev->devres_head, entry) {
		struct devres_group *grp;

		if (node->release != &group_open_release)
			continue;

		grp = container_of(node, struct devres_group, node[0]);

		if (id) {
			if (grp->id == id)
				return grp;
		} else if (list_empty(&grp->node[1].entry))
			return grp;
	}

	return NULL;
}

/**
 * devres_close_group - Close a devres group
 * @dev: Device to close devres group for
 * @id: ID of target group, can be NULL
 *
 * Close the group identified by @id.  If @id is NULL, the latest open
 * group is selected.
 */
void devres_close_group(struct device *dev, void *id)
{
	struct devres_group *grp;
	unsigned long flags;

	spin_lock_irqsave(&dev->devres_lock, flags);

	grp = find_group(dev, id);
	if (grp)
		add_dr(dev, &grp->node[1]);
	else
		WARN_ON(1);

	spin_unlock_irqrestore(&dev->devres_lock, flags);
}
EXPORT_SYMBOL_GPL(devres_close_group);

/**
 * devres_remove_group - Remove a devres group
 * @dev: Device to remove group for
 * @id: ID of target group, can be NULL
 *
 * Remove the group identified by @id.  If @id is NULL, the latest
 * open group is selected.  Note that removing a group doesn't affect
 * any other resources.
 */
void devres_remove_group(struct device *dev, void *id)
{
	struct devres_group *grp;
	unsigned long flags;

	spin_lock_irqsave(&dev->devres_lock, flags);

	grp = find_group(dev, id);
	if (grp) {
		list_del_init(&grp->node[0].entry);
		list_del_init(&grp->node[1].entry);
		devres_log(dev, &grp->node[0], "REM");
	} else
		WARN_ON(1);

	spin_unlock_irqrestore(&dev->devres_lock, flags);

	kfree(grp);
}
EXPORT_SYMBOL_GPL(devres_remove_group);

/**
 * devres_release_group - Release resources in a devres group
 * @dev: Device to release group for
 * @id: ID of target group, can be NULL
 *
 * Release all resources in the group identified by @id.  If @id is
 * NULL, the latest open group is selected.  The selected group and
 * groups properly nested inside the selected group are removed.
 *
 * RETURNS:
 * The number of released non-group resources.
 */
int devres_release_group(struct device *dev, void *id)
{
	struct devres_group *grp;
	unsigned long flags;
	int cnt = 0;

	spin_lock_irqsave(&dev->devres_lock, flags);

	grp = find_group(dev, id);
	if (grp) {
		struct list_head *first = &grp->node[0].entry;
		struct list_head *end = &dev->devres_head;

		if (!list_empty(&grp->node[1].entry))
			end = grp->node[1].entry.next;

		cnt = release_nodes(dev, first, end, flags);
	} else {
		WARN_ON(1);
		spin_unlock_irqrestore(&dev->devres_lock, flags);
	}

	return cnt;
}
EXPORT_SYMBOL_GPL(devres_release_group);

/*
 * Managed kzalloc/kfree
 */
static void devm_kzalloc_release(struct device *dev, void *res)
{
	/* noop */
}

static int devm_kzalloc_match(struct device *dev, void *res, void *data)
{
	return res == data;
}

/**
 * devm_kzalloc - Resource-managed kzalloc
 * @dev: Device to allocate memory for
 * @size: Allocation size
 * @gfp: Allocation gfp flags
 *
 * Managed kzalloc.  Memory allocated with this function is
 * automatically freed on driver detach.  Like all other devres
 * resources, guaranteed alignment is unsigned long long.
 *
 * RETURNS:
 * Pointer to allocated memory on success, NULL on failure.
 */
void * devm_kzalloc(struct device *dev, size_t size, gfp_t gfp)
{
	struct devres *dr;

	/* use raw alloc_dr for kmalloc caller tracing */
	dr = alloc_dr(devm_kzalloc_release, size, gfp);
	if (unlikely(!dr))
		return NULL;

	set_node_dbginfo(&dr->node, "devm_kzalloc_release", size);
	devres_add(dev, dr->data);
	return dr->data;
}
EXPORT_SYMBOL_GPL(devm_kzalloc);

/**
 * devm_kfree - Resource-managed kfree
 * @dev: Device this memory belongs to
 * @p: Memory to free
 *
 * Free memory allocated with devm_kzalloc().
 */
void devm_kfree(struct device *dev, void *p)
{
	int rc;

	rc = devres_destroy(dev, devm_kzalloc_release, devm_kzalloc_match, p);
	WARN_ON(rc);
}
EXPORT_SYMBOL_GPL(devm_kfree);