Re: [PATCH 1/2] add tunable_notifier function

[Randy Dunlap <randy.dunlap@oracle.com>]

On Thu, 04 Oct 2007 20:38:34 +0900 Takenori Nagano wrote:

> This patch adds new notifier function tunable_notifier_chain. Its base is
> atomic_notifier_chain.
> 
> Thanks,
> 
> ---
> 
> Signed-off-by: Takenori Nagano <t-nagano@ah.jp.nec.com>
> 
> ---

> diff -uprN linux-2.6.23-rc9.orig/kernel/sys.c linux-2.6.23-rc9/kernel/sys.c
> --- linux-2.6.23-rc9.orig/kernel/sys.c	2007-10-02 12:24:52.000000000 +0900
> +++ linux-2.6.23-rc9/kernel/sys.c	2007-10-03 14:48:15.160000000 +0900
> @@ -38,6 +38,7 @@
>  #include <linux/syscalls.h>
>  #include <linux/kprobes.h>
>  #include <linux/user_namespace.h>
> +#include <linux/debugfs.h>
> 
>  #include <asm/uaccess.h>
>  #include <asm/io.h>
> @@ -393,6 +394,234 @@ int blocking_notifier_call_chain(struct

> +/**
> + *	tunable_notifier_chain_register - Add notifier to an tunable notifier chain
> + *	@nh: Pointer to head of the tunable notifier chain
> + *	@n: New entry in notifier chain
> + *	@name: Pointer to the name of this notifier chain

Is @name the name of a notifier chain or of the new notifier entry?


> + *	@desc: Pointer to the description of new entry
> + *
> + *	Adds a notifier to an tunable notifier chain and makes control dir.
> + *
> + *	Returns zero on success or %-ENODEV on failure.
> + */
> +
> +int tunable_notifier_chain_register(struct tunable_notifier_head *nh,
> +		struct tunable_notifier_block *n, char *name, char *desc)
> +{
> +	unsigned long flags;
> +	int ret = -EINVAL;
> +	struct dentry *nh_dir, *nb_dir, *pri_dentry, *desc_dentry = NULL;
> +
> +	if (!name)
> +		goto nb_fail;
> +
> +	ret = -ENOMEM;
> +	if (!nh->dir) {
> +		nh_dir = debugfs_create_dir(nh->name, NULL);
> +		if (!nh_dir)
> +			return ret;
> +		nh->dir = nh_dir;
> +	} else
> +		nh_dir = nh->dir;
> +
> +	nb_dir = debugfs_create_dir(name, nh_dir);
> +	if (!nb_dir)
> +		goto nb_fail;
> +	n->dir = nb_dir;
> +
> +	pri_dentry = debugfs_create_file("priority",0600, nb_dir, n, &pri_fops);
> +	if (!pri_dentry)
> +		goto pri_fail;
> +	n->pri_dentry = pri_dentry;
> +
> +	if (desc) {
> +		desc_dentry = debugfs_create_file("description", 0400, nb_dir,
> +							desc, &desc_fops);
> +		if (!desc_dentry)
> +			goto desc_fail;
> +		n->desc_dentry = desc_dentry;
> +	}
> +
> +	spin_lock_irqsave(&nh->lock, flags);
> +	ret = notifier_chain_register(&nh->head, n->nb);
> +	spin_unlock_irqrestore(&nh->lock, flags);
> +
> +	if (ret)
> +		goto reg_fail;
> +	
> +	n->head = nh;
> +
> +	return ret;
> +
> +reg_fail:
> +	debugfs_remove(desc_dentry);
> +desc_fail:
> +	debugfs_remove(pri_dentry);
> +pri_fail:
> +	debugfs_remove(nb_dir);
> +nb_fail:
> +	return ret;
> +}
> +
> +EXPORT_SYMBOL_GPL(tunable_notifier_chain_register);

---
~Randy