Subject: [PATCH] pppol2tp: stop using proc internals

From: Alexey Dobriyan <[email-masked]>
Date: Sun, 25 Jan 2009 01:00:48 +0300

On Fri, Jan 23, 2009 at 10:09:55AM +0300, Cyrill Gorcunov wrote:
> [Stephen Rothwell - Fri, Jan 23, 2009 at 05:15:15PM +1100]
> | Hi Alexey,
> | 
> | Today's linux-next build (powerpc ppc64_defconfig) failed like this:
> | 
> | drivers/net/pppoe.c: In function 'pppoe_seq_open':
> | drivers/net/pppoe.c:1102: error: implicit declaration of function 'PDE_NET'
> | drivers/net/pppol2tp.c: In function 'pppol2tp_proc_open':
> | drivers/net/pppol2tp.c:2579: error: implicit declaration of function 'PDE_NET'
> | 
> | Caused by commits a6bcf1c1d38e0672db35e0d9f2504ac04ddf3ed5 ("net: pppoe -
> | introduce net-namespace functionality") and
> | 4e9fb8016a351b5b9da7fea32bcfdbc9d836e421 ("net: pppol2tp - introduce
> | net-namespace functionality") from the net tree interacting with commit
> | 0e6a2bfcbae4ee3cf770a6a5da203b4a336ff8ff ("proc 5/6: simplify network
> | namespace lookup") from the proc tree.
> | 
> | I added the following fix to the merge and can carry it as necessary.
> | 
> | I expect that there is a better fix for this, though.  These are the only
> | references to PDE_NET outside fs/proc.
> | -- 
> | Cheers,
> | Stephen Rothwell                    [email-masked]
> | http://www.canb.auug.org.au/~sfr/
> | 
> | diff --git a/drivers/net/pppoe.c b/drivers/net/pppoe.c
> | index 798b8cf..3aabf92 100644
> | --- a/drivers/net/pppoe.c
> | +++ b/drivers/net/pppoe.c
> | @@ -1099,7 +1099,7 @@ static int pppoe_seq_open(struct inode *inode, struct file *file)
> |  		return err;
> |  
> |  	m = file->private_data;
> | -	net = maybe_get_net(PDE_NET(PDE(inode)));
> | +	net = maybe_get_net(inode->i_sb->s_fs_info);
> |  	BUG_ON(!net);
> |  	m->private = net;
> |  
> | diff --git a/drivers/net/pppol2tp.c b/drivers/net/pppol2tp.c
> | index 056e22a..d21470f 100644
> | --- a/drivers/net/pppol2tp.c
> | +++ b/drivers/net/pppol2tp.c
> | @@ -2576,7 +2576,7 @@ static int pppol2tp_proc_open(struct inode *inode, struct file *file)
> |  		goto out;
> |  
> |  	pd = m->private;
> | -	net = maybe_get_net(PDE_NET(PDE(inode)));
> | +	net = maybe_get_net(inode->i_sb->s_fs_info);

Someone with ppp setup, please test this:

[PATCH] pppol2tp: stop using proc internals

PDE_NET usage in driver code is a sign and, indeed, switching
to seq_open_net/seq_release_net saves code and fixes bogus things, like
user triggerabble BUG_ON(!net) after maybe_get_net, and NULLifying ->private.

Signed-off-by: Alexey Dobriyan <[email-masked]>
---

 drivers/net/pppol2tp.c |   48 +++++-------------------------------------------
 1 file changed, 5 insertions(+), 43 deletions(-)

--- a/drivers/net/pppol2tp.c
+++ b/drivers/net/pppol2tp.c
@@ -2371,7 +2371,7 @@ end:
 #include <linux/seq_file.h>
 
 struct pppol2tp_seq_data {
-	struct net *seq_net;			/* net of inode */
+	struct seq_net_private p;
 	struct pppol2tp_tunnel *tunnel;		/* current tunnel */
 	struct pppol2tp_session *session;	/* NULL means get first session in tunnel */
 };
@@ -2436,7 +2436,7 @@ static void *pppol2tp_seq_start(struct seq_file *m, loff_t *offs)
 
 	BUG_ON(m->private == NULL);
 	pd = m->private;
-	pn = pppol2tp_pernet(pd->seq_net);
+	pn = pppol2tp_pernet(seq_file_net(m));
 
 	if (pd->tunnel == NULL) {
 		if (!list_empty(&pn->pppol2tp_tunnel_list))
@@ -2558,46 +2558,8 @@ static const struct seq_operations pppol2tp_seq_ops = {
  */
 static int pppol2tp_proc_open(struct inode *inode, struct file *file)
 {
-	struct seq_file *m;
-	struct pppol2tp_seq_data *pd;
-	struct net *net;
-	int ret = 0;
-
-	ret = seq_open(file, &pppol2tp_seq_ops);
-	if (ret < 0)
-		goto out;
-
-	m = file->private_data;
-
-	/* Allocate and fill our proc_data for access later */
-	ret = -ENOMEM;
-	m->private = kzalloc(sizeof(*pd), GFP_KERNEL);
-	if (m->private == NULL)
-		goto out;
-
-	pd = m->private;
-	net = maybe_get_net(PDE_NET(PDE(inode)));
-	BUG_ON(!net);
-	pd->seq_net = net;
-	return 0;
-
-out:
-	return ret;
-}
-
-/* Called when /proc file access completes.
- */
-static int pppol2tp_proc_release(struct inode *inode, struct file *file)
-{
-	struct seq_file *m = (struct seq_file *)file->private_data;
-	struct pppol2tp_seq_data *pd = m->private;
-
-	put_net(pd->seq_net);
-
-	kfree(m->private);
-	m->private = NULL;
-
-	return seq_release(inode, file);
+	return seq_open_net(inode, file, &pppol2tp_seq_ops,
+			    sizeof(struct pppol2tp_seq_data));
 }
 
 static const struct file_operations pppol2tp_proc_fops = {
@@ -2605,7 +2567,7 @@ static const struct file_operations pppol2tp_proc_fops = {
 	.open		= pppol2tp_proc_open,
 	.read		= seq_read,
 	.llseek		= seq_lseek,
-	.release	= pppol2tp_proc_release,
+	.release	= seq_release_net,
 };
 
 #endif /* CONFIG_PROC_FS */