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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 "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.
 *
 * 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)
{
      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;

      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 dev_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);

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