devres.c

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/*
 * drivers/base/devres.c - device resource management
 *
 * Copyright (c) 2006  SUSE Linux Products GmbH
 * Copyright (c) 2006  Tejun Heo <[email protected]>
 *
 * 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

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

void devres_for_each_res(struct device *dev, dr_release_t release,
            dr_match_t match, void *match_data,
            void (*fn)(struct device *, void *, void *),
            void *data)
{
    struct devres_node *node;
    struct devres_node *tmp;
    unsigned long flags;

    if (!fn)
        return;

    spin_lock_irqsave(&dev->devres_lock, flags);
    list_for_each_entry_safe_reverse(node, tmp,
            &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;
        fn(dev, dr->data, data);
    }
    spin_unlock_irqrestore(&dev->devres_lock, flags);
}
EXPORT_SYMBOL_GPL(devres_for_each_res);

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);

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;
}

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);

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);

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);

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);


int devres_release(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;

    (*release)(dev, res);
    devres_free(res);
    return 0;
}
EXPORT_SYMBOL_GPL(devres_release);

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;
}

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);
}

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;
}

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);

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);

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;
}

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);

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);