[RFT] covert br2684 to seq_file

[Stephen Hemminger <shemminger@xxxxxxxx>]

Convert the /proc/net/atm/br2684 to seq_file interface.
It builds and runs, but without any real atm hardware the table
is empty...

Patch is against 2.6-test4 bk latest.

diff -Nru a/net/atm/br2684.c b/net/atm/br2684.c
--- a/net/atm/br2684.c  Tue Sep  2 10:37:52 2003
+++ b/net/atm/br2684.c  Tue Sep  2 10:37:52 2003
@@ -18,6 +18,7 @@
 #include <net/arp.h>
 #include <linux/atm.h>
 #include <linux/atmdev.h>
+#include <linux/seq_file.h>
 
 #include <linux/atmbr2684.h>
 
@@ -666,31 +667,57 @@
        return -ENOIOCTLCMD;
 }
 
-/* Never put more than 256 bytes in at once */
-static int br2684_proc_engine(loff_t pos, char *buf)
+#ifdef CONFIG_PROC_FS
+static void *br2684_seq_start(struct seq_file *seq, loff_t *pos)
 {
-       struct list_head *lhd, *lhc;
-       struct net_device *net_dev;
-       struct br2684_dev *brdev;
-       struct br2684_vcc *brvcc;
-       list_for_each(lhd, &br2684_devs) {
-               net_dev = list_entry_brdev(lhd);
-               brdev = BRPRIV(net_dev);
-               if (pos-- == 0)
-                       return sprintf(buf, "dev %.16s: num=%d, mac=%02X:%02X:"
-                           "%02X:%02X:%02X:%02X (%s)\n", net_dev->name,
-                           brdev->number,
-                           net_dev->dev_addr[0],
-                           net_dev->dev_addr[1],
-                           net_dev->dev_addr[2],
-                           net_dev->dev_addr[3],
-                           net_dev->dev_addr[4],
-                           net_dev->dev_addr[5],
-                           brdev->mac_was_set ? "set" : "auto");
-               list_for_each(lhc, &brdev->brvccs) {
-                       brvcc = list_entry_brvcc(lhc);
-                       if (pos-- == 0)
-                               return sprintf(buf, "  vcc %d.%d.%d: encaps=%s"
+       loff_t offs = 0;
+       struct br2684_dev *brd;
+
+       read_lock(&devs_lock);
+
+       list_for_each_entry(brd, &br2684_devs, br2684_devs) {
+               if (offs == *pos)
+                       return brd;
+               ++offs;
+       }
+       return NULL;
+}
+
+static void *br2684_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+       struct br2684_dev *brd = v;
+
+       ++*pos;
+
+       brd = list_entry(brd->br2684_devs.next, 
+                        struct br2684_dev, br2684_devs);
+       return (&brd->br2684_devs != &br2684_devs) ? brd : NULL;
+}
+
+static void br2684_seq_stop(struct seq_file *seq, void *v)
+{
+       read_unlock(&devs_lock);
+}
+
+static int br2684_seq_show(struct seq_file *seq, void *v)
+{
+       const struct br2684_dev *brdev = v;
+       const struct net_device *net_dev = brdev->net_dev;
+       const struct br2684_vcc *brvcc;
+
+       seq_printf(seq, "dev %.16s: num=%d, mac=%02X:%02X:"
+                      "%02X:%02X:%02X:%02X (%s)\n", net_dev->name,
+                      brdev->number,
+                      net_dev->dev_addr[0],
+                      net_dev->dev_addr[1],
+                      net_dev->dev_addr[2],
+                      net_dev->dev_addr[3],
+                      net_dev->dev_addr[4],
+                      net_dev->dev_addr[5],
+                      brdev->mac_was_set ? "set" : "auto");
+
+       list_for_each_entry(brvcc, &brdev->brvccs, brvccs) {
+               seq_printf(seq, "  vcc %d.%d.%d: encaps=%s"
 #ifndef FASTER_VERSION
                                    ", failed copies %u/%u"
 #endif /* FASTER_VERSION */
@@ -711,63 +738,41 @@
 #undef bs
 #undef b1
 #endif /* CONFIG_ATM_BR2684_IPFILTER */
-               }
        }
        return 0;
 }
 
-static ssize_t br2684_proc_read(struct file *file, char *buf, size_t count,
-       loff_t *pos)
+static struct seq_operations br2684_seq_ops = {
+       .start = br2684_seq_start,
+       .next  = br2684_seq_next,
+       .stop  = br2684_seq_stop,
+       .show  = br2684_seq_show,
+};
+
+static int br2684_proc_open(struct inode *inode, struct file *file)
 {
-       unsigned long page;
-       int len = 0, x, left;
-       page = get_zeroed_page(GFP_KERNEL);
-       if (!page)
-               return -ENOMEM;
-       left = PAGE_SIZE - 256;
-       if (count < left)
-               left = count;
-       read_lock(&devs_lock);
-       for (;;) {
-               x = br2684_proc_engine(*pos, &((char *) page)[len]);
-               if (x == 0)
-                       break;
-               if (x > left)
-                       /*
-                        * This should only happen if the user passed in
-                        * a "count" too small for even one line
-                        */
-                       x = -EINVAL;
-               if (x < 0) {
-                       len = x;
-                       break;
-               }
-               len += x;
-               left -= x;
-               (*pos)++;
-               if (left < 256)
-                       break;
-       }
-       read_unlock(&devs_lock);
-       if (len > 0 && copy_to_user(buf, (char *) page, len))
-               len = -EFAULT;
-       free_page(page);
-       return len;
+       return seq_open(file, &br2684_seq_ops);
 }
 
 static struct file_operations br2684_proc_operations = {
        .owner = THIS_MODULE,
-       .read =  br2684_proc_read,
+       .open = br2684_proc_open,
+       .read    = seq_read,
+       .llseek  = seq_lseek,
+       .release = seq_release,
 };
 
 extern struct proc_dir_entry *atm_proc_root;   /* from proc.c */
+#endif
 
 static int __init br2684_init(void)
 {
+#ifdef CONFIG_PROC_FS
        struct proc_dir_entry *p;
        if ((p = create_proc_entry("br2684", 0, atm_proc_root)) == NULL)
                return -ENOMEM;
        p->proc_fops = &br2684_proc_operations;
+#endif
        br2684_ioctl_set(br2684_ioctl);
        return 0;
 }