[KEY]: Convert net/pfkey to use seq files.

The seq files API disposes the caller of the difficulty of
checking file position, the length of data to produce and
the size of provided buffer.

Signed-off-by: Pavel Emelyanov <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/key/af_key.c

···
 };
 
 #ifdef CONFIG_PROC_FS
-static int pfkey_read_proc(char *buffer, char **start, off_t offset,
-			   int length, int *eof, void *data)
+static int pfkey_seq_show(struct seq_file *f, void *v)
 {
-	off_t pos = 0;
-	off_t begin = 0;
-	int len = 0;
 	struct sock *s;
-	struct hlist_node *node;
 
-	len += sprintf(buffer,"sk       RefCnt Rmem   Wmem   User   Inode\n");
-
-	read_lock(&pfkey_table_lock);
-
-	sk_for_each(s, node, &pfkey_table) {
-		len += sprintf(buffer+len,"%p %-6d %-6u %-6u %-6u %-6lu",
+	s = (struct sock *)v;
+	if (v == SEQ_START_TOKEN)
+		seq_printf(f ,"sk       RefCnt Rmem   Wmem   User   Inode\n");
+	else
+		seq_printf(f ,"%p %-6d %-6u %-6u %-6u %-6lu\n",
 			       s,
 			       atomic_read(&s->sk_refcnt),
 			       atomic_read(&s->sk_rmem_alloc),
···
 			       sock_i_uid(s),
 			       sock_i_ino(s)
 			       );
-
-		buffer[len++] = '\n';
-
-		pos = begin + len;
-		if (pos < offset) {
-			len = 0;
-			begin = pos;
-		}
-		if(pos > offset + length)
-			goto done;
-	}
-	*eof = 1;
-
-done:
-	read_unlock(&pfkey_table_lock);
-
-	*start = buffer + (offset - begin);
-	len -= (offset - begin);
-
-	if (len > length)
-		len = length;
-	if (len < 0)
-		len = 0;
-
-	return len;
+	return 0;
 }
+
+static void *pfkey_seq_start(struct seq_file *f, loff_t *ppos)
+{
+	struct sock *s;
+	struct hlist_node *node;
+	loff_t pos = *ppos;
+
+	read_lock(&pfkey_table_lock);
+	if (pos == 0)
+		return SEQ_START_TOKEN;
+
+	sk_for_each(s, node, &pfkey_table)
+		if (pos-- == 1)
+			return s;
+
+	return NULL;
+}
+
+static void *pfkey_seq_next(struct seq_file *f, void *v, loff_t *ppos)
+{
+	++*ppos;
+	return (v == SEQ_START_TOKEN) ?
+		sk_head(&pfkey_table) :
+			sk_next((struct sock *)v);
+}
+
+static void pfkey_seq_stop(struct seq_file *f, void *v)
+{
+	read_unlock(&pfkey_table_lock);
+}
+
+static struct seq_operations pfkey_seq_ops = {
+	.start	= pfkey_seq_start,
+	.next	= pfkey_seq_next,
+	.stop	= pfkey_seq_stop,
+	.show	= pfkey_seq_show,
+};
+
+static int pfkey_seq_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &pfkey_seq_ops);
+}
+
+static struct file_operations pfkey_proc_ops = {
+	.open	 = pfkey_seq_open,
+	.read	 = seq_read,
+	.llseek	 = seq_lseek,
+	.release = seq_release,
+};
 
 static int pfkey_init_proc(void)
 {
-	if (create_proc_read_entry("pfkey", 0, init_net.proc_net,
-				pfkey_read_proc, NULL) == NULL)
+	struct proc_dir_entry *e;
+
+	e = create_proc_entry("pfkey", 0, init_net.proc_net);
+	if (e == NULL)
 		return -ENOMEM;
-	else
-		return 0;
+
+	e->proc_fops = &pfkey_proc_ops;
+	return 0;
 }
 
 static void pfkey_exit_proc(void)