kernfs_link_sibling

来源：互联网发布：iphone移动数据快速编辑：程序博客网时间：2024/06/15 05:32

文件/fs/kernfs/dir.c

/**
* kernfs_link_sibling - 链接kernfs_node到sibling rbtree(兄弟红黑树)上
* @kn: kernfs_node of interest
*
* Link @kn into its sibling rbtree which starts from
* @kn->parent->dir.children.
*
* Locking:
* mutex_lock(kernfs_mutex)
*
* RETURNS:
* 成功返回0，失败返回 -EEXIST
*/
static int kernfs_link_sibling(struct kernfs_node *kn)
{
struct rb_node **node = &kn->parent->dir.children.rb_node;
  struct rb_node *parent = NULL;

  if (kernfs_type(kn) == KERNFS_DIR)
      kn->parent->dir.subdirs++;

  while (*node) {
      struct kernfs_node *pos;
      int result;

      pos = rb_to_kn(*node);
      parent = *node;
      result = kernfs_sd_compare(kn, pos);
      if (result < 0)
          node = &pos->rb.rb_left;
      else if (result > 0)
          node = &pos->rb.rb_right;
      else
          return -EEXIST;
  }
  /* add new node and rebalance the tree */
  rb_link_node(&kn->rb, parent, node);
  rb_insert_color(&kn->rb, &kn->parent->dir.children);
  return 0;
}

#define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb)

文件/include/linux/rbtree.h

#define rb_entry(ptr, type, member) container_of(ptr, type, member)

莫名其妙就跑到红黑树的源码里面去了，好吧，下次再也不能说我不知道红黑树是个什么东西了，具体实现还是放到以后研究，总之从感性上来看，红黑树是一个高性能的二叉树

文件/fs/kernfs/dir.c

static int kernfs_sd_compare(const struct kernfs_node *left,
const struct kernfs_node *right)
{
return kernfs_name_compare(left->hash, left->name, left->ns, right);
}

static int kernfs_name_compare(unsigned int hash, const char *name,
const void *ns, const struct kernfs_node *kn)
{
  if (hash != kn->hash)
      return hash - kn->hash;
  if (ns != kn->ns)
      return ns - kn->ns;
  return strcmp(name, kn->name);
}

关于红黑树的实现，可以参考http://kerneltravel.net/jiaoliu/kern-rbtree.html

这里才总算是把该kobject加入到了sysfs中.

0 0