proc_fops: convert drivers/isdn/ to seq_file

Convert code away from ->read_proc/->write_proc interfaces.  Switch to
proc_create()/proc_create_data() which make addition of proc entries
reliable wrt NULL ->proc_fops, NULL ->data and so on.

Problem with ->read_proc et al is described here commit
786d7e1612 "Fix rmmod/read/write races in
/proc entries"

[akpm@linux-foundation.org: CONFIG_PROC_FS=n build fix]
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: Karsten Keil <keil@b1-systems.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/isdn/hysdn/hycapi.c

@@ -11,6 +11,8 @@
  */
 
 #include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
 #include <linux/signal.h>
 #include <linux/kernel.h>
 #include <linux/skbuff.h>
@@ -432,26 +434,16 @@ static u16 hycapi_send_message(struct capi_ctr *ctrl, struct sk_buff *skb)
 	return retval;
 }
 
-/*********************************************************************
-hycapi_read_proc
-
-Informations provided in the /proc/capi-entries.
-
-*********************************************************************/
-
-static int hycapi_read_proc(char *page, char **start, off_t off,
-			    int count, int *eof, struct capi_ctr *ctrl)
+static int hycapi_proc_show(struct seq_file *m, void *v)
 {
+	struct capi_ctr *ctrl = m->private;
 	hycapictrl_info *cinfo = (hycapictrl_info *)(ctrl->driverdata);
 	hysdn_card *card = cinfo->card;
-	int len = 0;
 	char *s;
-#ifdef HYCAPI_PRINTFNAMES
-	printk(KERN_NOTICE "hycapi_read_proc\n");    
-#endif
-	len += sprintf(page+len, "%-16s %s\n", "name", cinfo->cardname);
-	len += sprintf(page+len, "%-16s 0x%x\n", "io", card->iobase);
-	len += sprintf(page+len, "%-16s %d\n", "irq", card->irq);
+
+	seq_printf(m, "%-16s %s\n", "name", cinfo->cardname);
+	seq_printf(m, "%-16s 0x%x\n", "io", card->iobase);
+	seq_printf(m, "%-16s %d\n", "irq", card->irq);
     
 	switch (card->brdtype) {
 		case BD_PCCARD:  s = "HYSDN Hycard"; break;
@@ -461,24 +453,32 @@ static int hycapi_read_proc(char *page, char **start, off_t off,
 		case BD_PLEXUS: s = "HYSDN Plexus30"; break;
 		default: s = "???"; break;
 	}
-	len += sprintf(page+len, "%-16s %s\n", "type", s);
+	seq_printf(m, "%-16s %s\n", "type", s);
 	if ((s = cinfo->version[VER_DRIVER]) != NULL)
-		len += sprintf(page+len, "%-16s %s\n", "ver_driver", s);
+		seq_printf(m, "%-16s %s\n", "ver_driver", s);
 	if ((s = cinfo->version[VER_CARDTYPE]) != NULL)
-		len += sprintf(page+len, "%-16s %s\n", "ver_cardtype", s);
+		seq_printf(m, "%-16s %s\n", "ver_cardtype", s);
 	if ((s = cinfo->version[VER_SERIAL]) != NULL)
-		len += sprintf(page+len, "%-16s %s\n", "ver_serial", s);
+		seq_printf(m, "%-16s %s\n", "ver_serial", s);
     
-	len += sprintf(page+len, "%-16s %s\n", "cardname", cinfo->cardname);
+	seq_printf(m, "%-16s %s\n", "cardname", cinfo->cardname);
     
-	if (off+count >= len)
-		*eof = 1;
-	if (len < off)
-		return 0;
-	*start = page + off;
-	return ((count < len-off) ? count : len-off);
+	return 0;
 }
 
+static int hycapi_proc_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, hycapi_proc_show, PDE(inode)->data);
+}
+
+static const struct file_operations hycapi_proc_fops = {
+	.owner		= THIS_MODULE,
+	.open		= hycapi_proc_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
 /**************************************************************
 hycapi_load_firmware
 
@@ -774,7 +774,7 @@ hycapi_capi_create(hysdn_card *card)
 		ctrl->load_firmware = hycapi_load_firmware;
 		ctrl->reset_ctr     = hycapi_reset_ctr;
 		ctrl->procinfo      = hycapi_procinfo;
-		ctrl->ctr_read_proc = hycapi_read_proc;
+		ctrl->proc_fops = &hycapi_proc_fops;
 		strcpy(ctrl->name, cinfo->cardname);
 		ctrl->owner = THIS_MODULE;