Library function to create a seq_file in proc filesystem,
showing some information for each netdevice.
This code is present in the kernel in about 10 instances, and
all of them can be converted to using introduced library function.

Signed-off-by: Andrey Savochkin <saw@swsoft.com>

---
 include/linux/netdevice.h |    7 +++
 net/core/dev.c            |   96 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 103 insertions(+)

--- linux-2.6.19-rc6-mm2.orig/include/linux/netdevice.h
+++ linux-2.6.19-rc6-mm2/include/linux/netdevice.h
@@ -604,6 +604,13 @@ extern int		register_netdevice(struct ne
 extern int		unregister_netdevice(struct net_device *dev);
 extern void		free_netdev(struct net_device *dev);
 extern void		synchronize_net(void);
+#ifdef CONFIG_PROC_FS
+extern int		netdev_proc_create(char *name,
+				int (*show)(struct seq_file *,
+					struct net_device *, void *),
+				void *data, struct module *mod);
+void			netdev_proc_remove(char *name);
+#endif
 extern int 		register_netdevice_notifier(struct notifier_block *nb);
 extern int		unregister_netdevice_notifier(struct notifier_block *nb);
 extern int		call_netdevice_notifiers(unsigned long val, void *v);
--- linux-2.6.19-rc6-mm2.orig/net/core/dev.c
+++ linux-2.6.19-rc6-mm2/net/core/dev.c
@@ -2100,6 +2100,102 @@ static int dev_ifconf(char __user *arg)
 }
 
 #ifdef CONFIG_PROC_FS
+
+struct netdev_proc_data {
+	struct file_operations fops;
+	int (*show)(struct seq_file *, struct net_device *, void *);
+	void *data;
+};
+
+static void *netdev_proc_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	struct net_device *dev;
+	loff_t off;
+
+	read_lock(&dev_base_lock);
+	if (*pos == 0)
+		return SEQ_START_TOKEN;
+	for (dev = dev_base, off = 1; dev; dev = dev->next, off++) {
+		if (*pos == off)
+			return dev;
+	}
+	return NULL;
+}
+
+static void *netdev_proc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	++*pos;
+	return (v == SEQ_START_TOKEN) ? dev_base
+					: ((struct net_device *)v)->next;
+}
+
+static void netdev_proc_seq_stop(struct seq_file *seq, void *v)
+{
+	read_unlock(&dev_base_lock);
+}
+
+static int netdev_proc_seq_show(struct seq_file *seq, void *v)
+{
+	struct netdev_proc_data *p;
+
+	p = seq->private;
+	return (*p->show)(seq, v, p->data);
+}
+
+static struct seq_operations netdev_proc_seq_ops = {
+	.start = netdev_proc_seq_start,
+	.next  = netdev_proc_seq_next,
+	.stop  = netdev_proc_seq_stop,
+	.show  = netdev_proc_seq_show,
+};
+
+static int netdev_proc_open(struct inode *inode, struct file *file)
+{
+	int err;
+	struct seq_file *p;
+
+	err = seq_open(file, &netdev_proc_seq_ops);
+	if (!err) {
+		p = file->private_data;
+		p->private = (struct netdev_proc_data *)PDE(inode)->data;
+	}
+	return err;
+}
+
+int netdev_proc_create(char *name,
+		int (*show)(struct seq_file *, struct net_device *, void *),
+		void *data, struct module *mod)
+{
+	struct netdev_proc_data *p;
+	struct proc_dir_entry *ent;
+
+	p = kzalloc(sizeof(*p), GFP_KERNEL);
+	p->fops.owner = mod;
+	p->fops.open = netdev_proc_open;
+	p->fops.read = seq_read;
+	p->fops.llseek = seq_lseek;
+	p->fops.release = seq_release;
+	p->show = show;
+	p->data = data;
+	ent = create_proc_entry(name, S_IRUGO, proc_net);
+	if (ent == NULL) {
+		kfree(p);
+		return -EINVAL;
+	}
+	ent->data = p;
+	ent->destructor = proc_data_destructor;
+	smp_wmb();
+	ent->proc_fops = &p->fops;
+	return 0;
+}
+EXPORT_SYMBOL(netdev_proc_create);
+
+void netdev_proc_remove(char *name)
+{
+	proc_net_remove(name);
+}
+EXPORT_SYMBOL(netdev_proc_remove);
+
 /*
  *	This is invoked by the /proc filesystem handler to display a device
  *	in detail.
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On Wed, 17 Jan 2007 19:11:52 +0300
Dmitry Mishin <dim@openvz.org> wrote:

> Library function to create a seq_file in proc filesystem,
> showing some information for each netdevice.
> This code is present in the kernel in about 10 instances, and
> all of them can be converted to using introduced library function.
> 
> Signed-off-by: Andrey Savochkin <saw@swsoft.com>

But the implementations can use static data rather than allocation,
also the long term desire is to get rid of supporting most of these proc
interfaces.
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Stephen Hemminger <shemminger@osdl.org> writes:

> On Wed, 17 Jan 2007 19:11:52 +0300
> Dmitry Mishin <dim@openvz.org> wrote:
>
>> Library function to create a seq_file in proc filesystem,
>> showing some information for each netdevice.
>> This code is present in the kernel in about 10 instances, and
>> all of them can be converted to using introduced library function.
>> 
>> Signed-off-by: Andrey Savochkin <saw@swsoft.com>
>
> But the implementations can use static data rather than allocation,
> also the long term desire is to get rid of supporting most of these proc
> interfaces.

While we do have the interfaces we need to support them, and not
let them bit rot.

That said so long as we have to individually register and unregister
proc entries it is an active measure by the caller and they should
be able to handle allocation and freeing of data structures as well.

Eric
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