[PATCH] convert /proc/net/packet to seq_file

[Stephen Hemminger <shemminger@xxxxxxxx>]

Convert AF_PACKET's /proc interface to seq_file. No change in functionality,
but does fix problem with refcounting on this proc interface.

diff -Nru a/net/packet/af_packet.c b/net/packet/af_packet.c
--- a/net/packet/af_packet.c    Mon Jan  5 12:14:55 2004
+++ b/net/packet/af_packet.c    Mon Jan  5 12:14:55 2004
@@ -64,6 +64,7 @@
 #include <asm/uaccess.h>
 #include <asm/ioctls.h>
 #include <linux/proc_fs.h>
+#include <linux/seq_file.h>
 #include <linux/poll.h>
 #include <linux/module.h>
 #include <linux/init.h>
@@ -1767,61 +1768,86 @@
 };
 
 #ifdef CONFIG_PROC_FS
-static int packet_read_proc(char *buffer, char **start, off_t offset,
-                            int length, int *eof, void *data)
+static inline struct sock *packet_seq_idx(loff_t off)
 {
-       off_t pos=0;
-       off_t begin=0;
-       int len=0;
        struct sock *s;
        struct hlist_node *node;
-       
-       len+= sprintf(buffer,"sk       RefCnt Type Proto  Iface R Rmem   User   
Inode\n");
 
+       sk_for_each(s, node, &packet_sklist) {
+               if (!off--)
+                       return s;
+       }
+       return NULL;
+}
+
+static void *packet_seq_start(struct seq_file *seq, loff_t *pos)
+{
        read_lock(&packet_sklist_lock);
+       return *pos ? packet_seq_idx(*pos - 1) : SEQ_START_TOKEN;
+}
 
-       sk_for_each(s, node, &packet_sklist) {
-               struct packet_opt *po = pkt_sk(s);
+static void *packet_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+       ++*pos;
+       return  (v == SEQ_START_TOKEN) 
+               ? sk_head(&packet_sklist) 
+               : sk_next((struct sock*)v) ;
+}
 
-               len+=sprintf(buffer+len,"%p %-6d %-4d %04x   %-5d %1d %-6u %-6u 
%-6lu",
-                            s,
-                            atomic_read(&s->sk_refcnt),
-                            s->sk_type,
-                            ntohs(po->num),
-                            po->ifindex,
-                            po->running,
-                            atomic_read(&s->sk_rmem_alloc),
-                            sock_i_uid(s),
-                            sock_i_ino(s)
-                            );
+static void packet_seq_stop(struct seq_file *seq, void *v)
+{
+       read_unlock(&packet_sklist_lock);               
+}
 
-               buffer[len++]='\n';
-               
-               pos=begin+len;
-               if(pos<offset) {
-                       len=0;
-                       begin=pos;
-               }
-               if(pos>offset+length)
-                       goto done;
+static int packet_seq_show(struct seq_file *seq, void *v) 
+{
+       if (v == SEQ_START_TOKEN)
+               seq_puts(seq, "sk       RefCnt Type Proto  Iface R Rmem   User  
 Inode\n");
+       else {
+               struct sock *s = v;
+               const struct packet_opt *po = pkt_sk(s);
+
+               seq_printf(seq,
+                          "%p %-6d %-4d %04x   %-5d %1d %-6u %-6u %-6lu\n",
+                          s,
+                          atomic_read(&s->sk_refcnt),
+                          s->sk_type,
+                          ntohs(po->num),
+                          po->ifindex,
+                          po->running,
+                          atomic_read(&s->sk_rmem_alloc),
+                          sock_i_uid(s),
+                          sock_i_ino(s) );
        }
-       *eof = 1;
 
-done:
-       read_unlock(&packet_sklist_lock);
-       *start=buffer+(offset-begin);
-       len-=(offset-begin);
-       if(len>length)
-               len=length;
-       if(len<0)
-               len=0;
-       return len;
+       return 0;
 }
+
+static struct seq_operations packet_seq_ops = {
+       .start  = packet_seq_start,
+       .next   = packet_seq_next,
+       .stop   = packet_seq_stop,
+       .show   = packet_seq_show,
+};
+
+static int packet_seq_open(struct inode *inode, struct file *file)
+{
+       return seq_open(file, &packet_seq_ops);
+}
+
+static struct file_operations packet_seq_fops = {
+       .owner          = THIS_MODULE,
+       .open           = packet_seq_open,
+       .read           = seq_read,
+       .llseek         = seq_lseek,
+       .release        = seq_release,
+};
+
 #endif
 
 static void __exit packet_exit(void)
 {
-       remove_proc_entry("net/packet", 0);
+       proc_net_remove("packet");
        unregister_netdevice_notifier(&packet_netdev_notifier);
        sock_unregister(PF_PACKET);
        return;
@@ -1831,9 +1857,8 @@
 {
        sock_register(&packet_family_ops);
        register_netdevice_notifier(&packet_netdev_notifier);
-#ifdef CONFIG_PROC_FS
-       create_proc_read_entry("net/packet", 0, 0, packet_read_proc, NULL);
-#endif
+       proc_net_fops_create("packet", 0, &packet_seq_fops);
+
        return 0;
 }