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
786d7e1 "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>

Author: Alexey Dobriyan

Documentation/isdn/INTERFACE.CAPI

@@ -149,10 +149,11 @@ char *(*procinfo)(struct capi_ctr *ctrlr)
 	pointer to a callback function returning the entry for the device in
 	the CAPI controller info table, /proc/capi/controller
 
-read_proc_t *ctr_read_proc
-	pointer to the read_proc callback function for the device's proc file
-	system entry, /proc/capi/controllers/<n>; will be called with a
-	pointer to the device's capi_ctr structure as the last (data) argument
+const struct file_operations *proc_fops
+	pointers to callback functions for the device's proc file
+	system entry, /proc/capi/controllers/<n>; pointer to the device's
+	capi_ctr structure is available from struct proc_dir_entry::data
+	which is available from struct inode.
 
 Note: Callback functions except send_message() are never called in interrupt
 context.

drivers/isdn/capi/capi.c

@@ -33,6 +33,7 @@
 #endif /* CONFIG_ISDN_CAPI_MIDDLEWARE */
 #include <linux/skbuff.h>
 #include <linux/proc_fs.h>
+#include <linux/seq_file.h>
 #include <linux/poll.h>
 #include <linux/capi.h>
 #include <linux/kernelcapi.h>
@@ -1407,114 +1408,84 @@ static void capinc_tty_exit(void)
  * /proc/capi/capi20:
  *  minor applid nrecvctlpkt nrecvdatapkt nsendctlpkt nsenddatapkt
  */
-static int proc_capidev_read_proc(char *page, char **start, off_t off,
-                                       int count, int *eof, void *data)
+static int capi20_proc_show(struct seq_file *m, void *v)
 {
         struct capidev *cdev;
 	struct list_head *l;
-	int len = 0;
 
 	read_lock(&capidev_list_lock);
 	list_for_each(l, &capidev_list) {
 		cdev = list_entry(l, struct capidev, list);
-		len += sprintf(page+len, "0 %d %lu %lu %lu %lu\n",
+		seq_printf(m, "0 %d %lu %lu %lu %lu\n",
 			cdev->ap.applid,
 			cdev->ap.nrecvctlpkt,
 			cdev->ap.nrecvdatapkt,
 			cdev->ap.nsentctlpkt,
 			cdev->ap.nsentdatapkt);
-		if (len <= off) {
-			off -= len;
-			len = 0;
-		} else {
-			if (len-off > count)
-				goto endloop;
-		}
 	}
-
-endloop:
 	read_unlock(&capidev_list_lock);
-	if (len < count)
-		*eof = 1;
-	if (len > count) len = count;
-	if (len < 0) len = 0;
-	return len;
+	return 0;
 }
 
+static int capi20_proc_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, capi20_proc_show, NULL);
+}
+
+static const struct file_operations capi20_proc_fops = {
+	.owner		= THIS_MODULE,
+	.open		= capi20_proc_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
 /*
  * /proc/capi/capi20ncci:
  *  applid ncci
  */
-static int proc_capincci_read_proc(char *page, char **start, off_t off,
-                                       int count, int *eof, void *data)
+static int capi20ncci_proc_show(struct seq_file *m, void *v)
 {
         struct capidev *cdev;
         struct capincci *np;
 	struct list_head *l;
-	int len = 0;
 
 	read_lock(&capidev_list_lock);
 	list_for_each(l, &capidev_list) {
 		cdev = list_entry(l, struct capidev, list);
 		for (np=cdev->nccis; np; np = np->next) {
-			len += sprintf(page+len, "%d 0x%x\n",
+			seq_printf(m, "%d 0x%x\n",
 				       cdev->ap.applid,
 				       np->ncci);
-			if (len <= off) {
-				off -= len;
-				len = 0;
-			} else {
-				if (len-off > count)
-					goto endloop;
-			}
 		}
 	}
-endloop:
 	read_unlock(&capidev_list_lock);
-	*start = page+off;
-	if (len < count)
-		*eof = 1;
-	if (len>count) len = count;
-	if (len<0) len = 0;
-	return len;
+	return 0;
 }
 
-static struct procfsentries {
-  char *name;
-  mode_t mode;
-  int (*read_proc)(char *page, char **start, off_t off,
-                                       int count, int *eof, void *data);
-  struct proc_dir_entry *procent;
-} procfsentries[] = {
-   /* { "capi",		  S_IFDIR, 0 }, */
-   { "capi/capi20", 	  0	 , proc_capidev_read_proc },
-   { "capi/capi20ncci",   0	 , proc_capincci_read_proc },
+static int capi20ncci_proc_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, capi20ncci_proc_show, NULL);
+}
+
+static const struct file_operations capi20ncci_proc_fops = {
+	.owner		= THIS_MODULE,
+	.open		= capi20ncci_proc_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
 };
 
 static void __init proc_init(void)
 {
-    int nelem = ARRAY_SIZE(procfsentries);
-    int i;
-
-    for (i=0; i < nelem; i++) {
-        struct procfsentries *p = procfsentries + i;
-	p->procent = create_proc_entry(p->name, p->mode, NULL);
-	if (p->procent) p->procent->read_proc = p->read_proc;
-    }
+	proc_create("capi/capi20", 0, NULL, &capi20_proc_fops);
+	proc_create("capi/capi20ncci", 0, NULL, &capi20ncci_proc_fops);
 }
 
 static void __exit proc_exit(void)
 {
-    int nelem = ARRAY_SIZE(procfsentries);
-    int i;
-
-    for (i=nelem-1; i >= 0; i--) {
-        struct procfsentries *p = procfsentries + i;
-	if (p->procent) {
-	   remove_proc_entry(p->name, NULL);
-	   p->procent = NULL;
-	}
-    }
+	remove_proc_entry("capi/capi20", NULL);
+	remove_proc_entry("capi/capi20ncci", NULL);
 }
 
 /* -------- init function and module interface ---------------------- */

drivers/isdn/capi/capidrv.c

@@ -24,6 +24,7 @@
 #include <linux/isdn.h>
 #include <linux/isdnif.h>
 #include <linux/proc_fs.h>
+#include <linux/seq_file.h>
 #include <linux/capi.h>
 #include <linux/kernelcapi.h>
 #include <linux/ctype.h>
@@ -2229,59 +2230,37 @@ static void lower_callback(unsigned int cmd, u32 contr, void *data)
  * /proc/capi/capidrv:
  * nrecvctlpkt nrecvdatapkt nsendctlpkt nsenddatapkt
  */
-static int proc_capidrv_read_proc(char *page, char **start, off_t off,
-                                       int count, int *eof, void *data)
+static int capidrv_proc_show(struct seq_file *m, void *v)
 {
-	int len = 0;
-
-	len += sprintf(page+len, "%lu %lu %lu %lu\n",
+	seq_printf(m, "%lu %lu %lu %lu\n",
 			global.ap.nrecvctlpkt,
 			global.ap.nrecvdatapkt,
 			global.ap.nsentctlpkt,
 			global.ap.nsentdatapkt);
-	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 capidrv_proc_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, capidrv_proc_show, NULL);
 }
 
-static struct procfsentries {
-  char *name;
-  mode_t mode;
-  int (*read_proc)(char *page, char **start, off_t off,
-                                       int count, int *eof, void *data);
-  struct proc_dir_entry *procent;
-} procfsentries[] = {
-   /* { "capi",		  S_IFDIR, 0 }, */
-   { "capi/capidrv", 	  0	 , proc_capidrv_read_proc },
+static const struct file_operations capidrv_proc_fops = {
+	.owner		= THIS_MODULE,
+	.open		= capidrv_proc_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
 };
 
 static void __init proc_init(void)
 {
-    int nelem = ARRAY_SIZE(procfsentries);
-    int i;
-
-    for (i=0; i < nelem; i++) {
-        struct procfsentries *p = procfsentries + i;
-	p->procent = create_proc_entry(p->name, p->mode, NULL);
-	if (p->procent) p->procent->read_proc = p->read_proc;
-    }
+	proc_create("capi/capidrv", 0, NULL, &capidrv_proc_fops);
 }
 
 static void __exit proc_exit(void)
 {
-    int nelem = ARRAY_SIZE(procfsentries);
-    int i;
-
-    for (i=nelem-1; i >= 0; i--) {
-        struct procfsentries *p = procfsentries + i;
-	if (p->procent) {
-	   remove_proc_entry(p->name, NULL);
-	   p->procent = NULL;
-	}
-    }
+	remove_proc_entry("capi/capidrv", NULL);
 }
 
 static int __init capidrv_init(void)

drivers/isdn/capi/kcapi.c

@@ -490,13 +490,7 @@ attach_capi_ctr(struct capi_ctr *card)
 	card->traceflag = showcapimsgs;
 
 	sprintf(card->procfn, "capi/controllers/%d", card->cnr);
-	card->procent = create_proc_entry(card->procfn, 0, NULL);
-	if (card->procent) {
-	   card->procent->read_proc = 
-		(int (*)(char *,char **,off_t,int,int *,void *))
-			card->ctr_read_proc;
-	   card->procent->data = card;
-	}
+	card->procent = proc_create_data(card->procfn, 0, NULL, card->proc_fops, card);
 
 	ncards++;
 	printk(KERN_NOTICE "kcapi: Controller [%03d]: %s attached\n",