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

[Stephen Hemminger <shemminger@xxxxxxxx>]

Convert /proc/net/dev_mcast for 2.6 so it will work with large number of 
interfaces.

diff -Nru a/net/core/dev_mcast.c b/net/core/dev_mcast.c
--- a/net/core/dev_mcast.c      Mon Jan 12 13:51:34 2004
+++ b/net/core/dev_mcast.c      Mon Jan 12 13:51:34 2004
@@ -41,6 +41,7 @@
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
 #include <linux/proc_fs.h>
+#include <linux/seq_file.h>
 #include <linux/init.h>
 #include <net/ip.h>
 #include <net/route.h>
@@ -219,59 +220,78 @@
 }
 
 #ifdef CONFIG_PROC_FS
-static int dev_mc_read_proc(char *buffer, char **start, off_t offset,
-                           int length, int *eof, void *data)
+static void *dev_mc_seq_start(struct seq_file *seq, loff_t *pos)
 {
-       off_t pos = 0, begin = 0;
-       struct dev_mc_list *m;
-       int len = 0;
        struct net_device *dev;
+       loff_t off = 0;
 
        read_lock(&dev_base_lock);
        for (dev = dev_base; dev; dev = dev->next) {
-               spin_lock_bh(&dev->xmit_lock);
-               for (m = dev->mc_list; m; m = m->next) {
-                       int i;
-
-                       len += sprintf(buffer+len,"%-4d %-15s %-5d %-5d ", 
dev->ifindex,
-                                      dev->name, m->dmi_users, m->dmi_gusers);
-
-                       for (i = 0; i < m->dmi_addrlen; i++)
-                               len += sprintf(buffer+len, "%02x", 
m->dmi_addr[i]);
-
-                       len += sprintf(buffer+len, "\n");
-
-                       pos = begin + len;
-                       if (pos < offset) {
-                               len = 0;
-                               begin = pos;
-                       }
-                       if (pos > offset + length) {
-                               spin_unlock_bh(&dev->xmit_lock);
-                               goto done;
-                       }
-               }
-               spin_unlock_bh(&dev->xmit_lock);
+               if (off++ == *pos) 
+                       return dev;
        }
-       *eof = 1;
+       return NULL;
+}
 
-done:
+static void *dev_mc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+       struct net_device *dev = v;
+       ++*pos;
+       return dev->next;
+}
+
+static void dev_mc_seq_stop(struct seq_file *seq, void *v)
+{
        read_unlock(&dev_base_lock);
-       *start = buffer + (offset - begin);
-       len -= (offset - begin);
-       if (len > length)
-               len = length;
-       if (len < 0)
-               len = 0;
-       return len;
 }
+
+
+static int dev_mc_seq_show(struct seq_file *seq, void *v)
+{
+       struct dev_mc_list *m;
+       struct net_device *dev = v;
+
+       spin_lock_bh(&dev->xmit_lock);
+       for (m = dev->mc_list; m; m = m->next) {
+               int i;
+
+               seq_printf(seq, "%-4d %-15s %-5d %-5d ", dev->ifindex,
+                          dev->name, m->dmi_users, m->dmi_gusers);
+
+               for (i = 0; i < m->dmi_addrlen; i++)
+                       seq_printf(seq, "%02x", m->dmi_addr[i]);
+
+               seq_putc(seq, '\n');
+       }
+       spin_unlock_bh(&dev->xmit_lock);
+       return 0;
+}
+
+static struct seq_operations dev_mc_seq_ops = {
+       .start = dev_mc_seq_start,
+       .next  = dev_mc_seq_next,
+       .stop  = dev_mc_seq_stop,
+       .show  = dev_mc_seq_show,
+};
+
+static int dev_mc_seq_open(struct inode *inode, struct file *file)
+{
+       return seq_open(file, &dev_mc_seq_ops);
+}
+
+static struct file_operations dev_mc_seq_fops = {
+       .owner   = THIS_MODULE,
+       .open    = dev_mc_seq_open,
+       .read    = seq_read,
+       .llseek  = seq_lseek,
+       .release = seq_release,
+};
+
 #endif
 
 void __init dev_mcast_init(void)
 {
-#ifdef CONFIG_PROC_FS
-       create_proc_read_entry("net/dev_mcast", 0, 0, dev_mc_read_proc, NULL);
-#endif
+       proc_net_fops_create("dev_mcast", 0, &dev_mc_seq_fops);
 }
 
 EXPORT_SYMBOL(dev_mc_add);