generic.c

linux 内核源代码

	return 1;
}

static struct dentry_operations proc_dentry_operations =
{
	.d_delete	= proc_delete_dentry,
};

/*
 * Don't create negative dentries here, return -ENOENT by hand
 * instead.
 */
struct dentry *proc_lookup(struct inode * dir, struct dentry *dentry, struct nameidata *nd)
{
	struct inode *inode = NULL;
	struct proc_dir_entry * de;
	int error = -ENOENT;

	lock_kernel();
	spin_lock(&proc_subdir_lock);
	de = PDE(dir);
	if (de) {
		for (de = de->subdir; de ; de = de->next) {
			if (de->namelen != dentry->d_name.len)
				continue;
			if (!memcmp(dentry->d_name.name, de->name, de->namelen)) {
				unsigned int ino;

				if (de->shadow_proc)
					de = de->shadow_proc(current, de);
				ino = de->low_ino;
				de_get(de);
				spin_unlock(&proc_subdir_lock);
				error = -EINVAL;
				inode = proc_get_inode(dir->i_sb, ino, de);
				spin_lock(&proc_subdir_lock);
				break;
			}
		}
	}
	spin_unlock(&proc_subdir_lock);
	unlock_kernel();

	if (inode) {
		dentry->d_op = &proc_dentry_operations;
		d_add(dentry, inode);
		return NULL;
	}
	de_put(de);
	return ERR_PTR(error);
}

/*
 * This returns non-zero if at EOF, so that the /proc
 * root directory can use this and check if it should
 * continue with the <pid> entries..
 *
 * Note that the VFS-layer doesn't care about the return
 * value of the readdir() call, as long as it's non-negative
 * for success..
 */
int proc_readdir(struct file * filp,
	void * dirent, filldir_t filldir)
{
	struct proc_dir_entry * de;
	unsigned int ino;
	int i;
	struct inode *inode = filp->f_path.dentry->d_inode;
	int ret = 0;

	lock_kernel();

	ino = inode->i_ino;
	de = PDE(inode);
	if (!de) {
		ret = -EINVAL;
		goto out;
	}
	i = filp->f_pos;
	switch (i) {
		case 0:
			if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
				goto out;
			i++;
			filp->f_pos++;
			/* fall through */
		case 1:
			if (filldir(dirent, "..", 2, i,
				    parent_ino(filp->f_path.dentry),
				    DT_DIR) < 0)
				goto out;
			i++;
			filp->f_pos++;
			/* fall through */
		default:
			spin_lock(&proc_subdir_lock);
			de = de->subdir;
			i -= 2;
			for (;;) {
				if (!de) {
					ret = 1;
					spin_unlock(&proc_subdir_lock);
					goto out;
				}
				if (!i)
					break;
				de = de->next;
				i--;
			}

			do {
				struct proc_dir_entry *next;

				/* filldir passes info to user space */
				de_get(de);
				spin_unlock(&proc_subdir_lock);
				if (filldir(dirent, de->name, de->namelen, filp->f_pos,
					    de->low_ino, de->mode >> 12) < 0) {
					de_put(de);
					goto out;
				}
				spin_lock(&proc_subdir_lock);
				filp->f_pos++;
				next = de->next;
				de_put(de);
				de = next;
			} while (de);
			spin_unlock(&proc_subdir_lock);
	}
	ret = 1;
out:	unlock_kernel();
	return ret;	
}

/*
 * These are the generic /proc directory operations. They
 * use the in-memory "struct proc_dir_entry" tree to parse
 * the /proc directory.
 */
static const struct file_operations proc_dir_operations = {
	.read			= generic_read_dir,
	.readdir		= proc_readdir,
};

/*
 * proc directories can do almost nothing..
 */
static const struct inode_operations proc_dir_inode_operations = {
	.lookup		= proc_lookup,
	.getattr	= proc_getattr,
	.setattr	= proc_notify_change,
};

static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp)
{
	unsigned int i;
	
	i = get_inode_number();
	if (i == 0)
		return -EAGAIN;
	dp->low_ino = i;

	if (S_ISDIR(dp->mode)) {
		if (dp->proc_iops == NULL) {
			dp->proc_fops = &proc_dir_operations;
			dp->proc_iops = &proc_dir_inode_operations;
		}
		dir->nlink++;
	} else if (S_ISLNK(dp->mode)) {
		if (dp->proc_iops == NULL)
			dp->proc_iops = &proc_link_inode_operations;
	} else if (S_ISREG(dp->mode)) {
		if (dp->proc_fops == NULL)
			dp->proc_fops = &proc_file_operations;
		if (dp->proc_iops == NULL)
			dp->proc_iops = &proc_file_inode_operations;
	}

	spin_lock(&proc_subdir_lock);
	dp->next = dir->subdir;
	dp->parent = dir;
	dir->subdir = dp;
	spin_unlock(&proc_subdir_lock);

	return 0;
}

static struct proc_dir_entry *proc_create(struct proc_dir_entry **parent,
					  const char *name,
					  mode_t mode,
					  nlink_t nlink)
{
	struct proc_dir_entry *ent = NULL;
	const char *fn = name;
	int len;

	/* make sure name is valid */
	if (!name || !strlen(name)) goto out;

	if (!(*parent) && xlate_proc_name(name, parent, &fn) != 0)
		goto out;

	/* At this point there must not be any '/' characters beyond *fn */
	if (strchr(fn, '/'))
		goto out;

	len = strlen(fn);

	ent = kmalloc(sizeof(struct proc_dir_entry) + len + 1, GFP_KERNEL);
	if (!ent) goto out;

	memset(ent, 0, sizeof(struct proc_dir_entry));
	memcpy(((char *) ent) + sizeof(struct proc_dir_entry), fn, len + 1);
	ent->name = ((char *) ent) + sizeof(*ent);
	ent->namelen = len;
	ent->mode = mode;
	ent->nlink = nlink;
	atomic_set(&ent->count, 1);
	ent->pde_users = 0;
	spin_lock_init(&ent->pde_unload_lock);
	ent->pde_unload_completion = NULL;
 out:
	return ent;
}

struct proc_dir_entry *proc_symlink(const char *name,
		struct proc_dir_entry *parent, const char *dest)
{
	struct proc_dir_entry *ent;

	ent = proc_create(&parent,name,
			  (S_IFLNK | S_IRUGO | S_IWUGO | S_IXUGO),1);

	if (ent) {
		ent->data = kmalloc((ent->size=strlen(dest))+1, GFP_KERNEL);
		if (ent->data) {
			strcpy((char*)ent->data,dest);
			if (proc_register(parent, ent) < 0) {
				kfree(ent->data);
				kfree(ent);
				ent = NULL;
			}
		} else {
			kfree(ent);
			ent = NULL;
		}
	}
	return ent;
}

struct proc_dir_entry *proc_mkdir_mode(const char *name, mode_t mode,
		struct proc_dir_entry *parent)
{
	struct proc_dir_entry *ent;

	ent = proc_create(&parent, name, S_IFDIR | mode, 2);
	if (ent) {
		if (proc_register(parent, ent) < 0) {
			kfree(ent);
			ent = NULL;
		}
	}
	return ent;
}

struct proc_dir_entry *proc_mkdir(const char *name,
		struct proc_dir_entry *parent)
{
	return proc_mkdir_mode(name, S_IRUGO | S_IXUGO, parent);
}

struct proc_dir_entry *create_proc_entry(const char *name, mode_t mode,
					 struct proc_dir_entry *parent)
{
	struct proc_dir_entry *ent;
	nlink_t nlink;

	if (S_ISDIR(mode)) {
		if ((mode & S_IALLUGO) == 0)
			mode |= S_IRUGO | S_IXUGO;
		nlink = 2;
	} else {
		if ((mode & S_IFMT) == 0)
			mode |= S_IFREG;
		if ((mode & S_IALLUGO) == 0)
			mode |= S_IRUGO;
		nlink = 1;
	}

	ent = proc_create(&parent,name,mode,nlink);
	if (ent) {
		if (proc_register(parent, ent) < 0) {
			kfree(ent);
			ent = NULL;
		}
	}
	return ent;
}

void free_proc_entry(struct proc_dir_entry *de)
{
	unsigned int ino = de->low_ino;

	if (ino < PROC_DYNAMIC_FIRST)
		return;

	release_inode_number(ino);

	if (S_ISLNK(de->mode) && de->data)
		kfree(de->data);
	kfree(de);
}

/*
 * Remove a /proc entry and free it if it's not currently in use.
 */
void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
{
	struct proc_dir_entry **p;
	struct proc_dir_entry *de;
	const char *fn = name;
	int len;

	if (!parent && xlate_proc_name(name, &parent, &fn) != 0)
		goto out;
	len = strlen(fn);

	spin_lock(&proc_subdir_lock);
	for (p = &parent->subdir; *p; p=&(*p)->next ) {
		if (!proc_match(len, fn, *p))
			continue;
		de = *p;
		*p = de->next;
		de->next = NULL;

		spin_lock(&de->pde_unload_lock);
		/*
		 * Stop accepting new callers into module. If you're
		 * dynamically allocating ->proc_fops, save a pointer somewhere.
		 */
		de->proc_fops = NULL;
		/* Wait until all existing callers into module are done. */
		if (de->pde_users > 0) {
			DECLARE_COMPLETION_ONSTACK(c);

			if (!de->pde_unload_completion)
				de->pde_unload_completion = &c;

			spin_unlock(&de->pde_unload_lock);
			spin_unlock(&proc_subdir_lock);

			wait_for_completion(de->pde_unload_completion);

			spin_lock(&proc_subdir_lock);
			goto continue_removing;
		}
		spin_unlock(&de->pde_unload_lock);

continue_removing:
		if (S_ISDIR(de->mode))
			parent->nlink--;
		de->nlink = 0;
		WARN_ON(de->subdir);
		if (atomic_dec_and_test(&de->count))
			free_proc_entry(de);
		break;
	}
	spin_unlock(&proc_subdir_lock);
out:
	return;
}