[PATCH] new helpers for /proc

new helpers for seq_file - for cases where we don't have a non-trivial
iterator and just want to use seq_{printf,putc,...}.

fs/proc/proc_misc.c

@@ -357,25 +357,7 @@ static int devices_read_proc(char *page, char **start, off_t off,
 	return proc_calc_metrics(page, start, off, count, eof, len);
 }
 
-static void *single_start(struct seq_file *p, loff_t *pos)
-{
-	return NULL + (*pos == 0);
-}
-static void *single_next(struct seq_file *p, void *v, loff_t *pos)
-{
-	++*pos;
-	return NULL;
-}
-static void single_stop(struct seq_file *p, void *v)
-{
-}
 extern int show_interrupts(struct seq_file *p, void *v);
-static struct seq_operations proc_interrupts_op = {
-	start:	single_start,
-	next:	single_next,
-	stop:	single_stop,
-	show:	show_interrupts,
-};
 static int interrupts_open(struct inode *inode, struct file *file)
 {
 	unsigned size = PAGE_SIZE;
@@ -389,7 +371,7 @@ static int interrupts_open(struct inode *inode, struct file *file)
 
 	if (!buf)
 		return -ENOMEM;
-	res = seq_open(file, &proc_interrupts_op);
+	res = single_open(file, show_interrupts, NULL);
 	if (!res) {
 		m = file->private_data;
 		m->buf = buf;
@@ -402,7 +384,7 @@ static struct file_operations proc_interrupts_operations = {
 	open:		interrupts_open,
 	read:		seq_read,
 	llseek:		seq_lseek,
-	release:	seq_release,
+	release:	single_release,
 };
 
 static int filesystems_read_proc(char *page, char **start, off_t off,

fs/seq_file.c

@@ -293,3 +293,45 @@ int seq_printf(struct seq_file *m, const char *f, ...)
 	m->count = m->size;
 	return -1;
 }
+
+static void *single_start(struct seq_file *p, loff_t *pos)
+{
+	return NULL + (*pos == 0);
+}
+
+static void *single_next(struct seq_file *p, void *v, loff_t *pos)
+{
+	++*pos;
+	return NULL;
+}
+
+static void single_stop(struct seq_file *p, void *v)
+{
+}
+
+int single_open(struct file *file, int (*show)(struct seq_file *, void*), void *data)
+{
+	struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL);
+	int res = -ENOMEM;
+
+	if (op) {
+		op->start = single_start;
+		op->next = single_next;
+		op->stop = single_stop;
+		op->show = show;
+		res = seq_open(file, op);
+		if (!res)
+			((struct seq_file *)file->private_data)->private = data;
+		else
+			kfree(op);
+	}
+	return res;
+}
+
+int single_release(struct inode *inode, struct file *file)
+{
+	struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
+	int res = seq_release(inode, file);
+	kfree(op);
+	return res;
+}

include/linux/seq_file.h

@@ -58,5 +58,7 @@ static inline int seq_puts(struct seq_file *m, const char *s)
 int seq_printf(struct seq_file *, const char *, ...)
 	__attribute__ ((format (printf,2,3)));
 
+int single_open(struct file *, int (*)(struct seq_file *, void *), void *);
+int single_release(struct inode *, struct file *);
 #endif
 #endif

kernel/ksyms.c

@@ -522,6 +522,8 @@ EXPORT_SYMBOL(seq_open);
 EXPORT_SYMBOL(seq_release);
 EXPORT_SYMBOL(seq_read);
 EXPORT_SYMBOL(seq_lseek);
+EXPORT_SYMBOL(single_open);
+EXPORT_SYMBOL(single_release);
 
 /* Program loader interfaces */
 EXPORT_SYMBOL(setup_arg_pages);

net/wanrouter/wanproc.c

@@ -233,18 +233,6 @@ static struct file_operations status_fops =
 	release:	seq_release,
 };
 
-static void *single_start(struct seq_file *p, loff_t *pos)
-{
-	return *pos == 0 ? p->private : NULL;
-}
-static void *single_next(struct seq_file *p, void *v, loff_t *pos)
-{
-	++*pos;
-	return NULL;
-}
-static void single_stop(struct seq_file *p, void *v)
-{
-}
 static int wandev_show(struct seq_file *m, void *v)
 {
 	wan_device_t *wandev = v;
@@ -306,20 +294,10 @@ static int wandev_show(struct seq_file *m, void *v)
 		"aborted frames transmitted", wandev->stats.tx_aborted_errors);
 	return 0;
 }
-static struct seq_operations wandev_op = {
-	start:	single_start,
-	next:	single_next,
-	stop:	single_stop,
-	show:	wandev_show,
-};
+
 static int wandev_open(struct inode *inode, struct file *file)
 {
-	int ret = seq_open(file, &wandev_op);
-	if (!ret) {
-		struct seq_file *m = file->private_data;
-		m->private = PDE(inode)->data;
-	}
-	return ret;
+	return single_open(file, wandev_show, PDE(inode)->data);
 }
 
 static struct file_operations wandev_fops =
@@ -327,7 +305,7 @@ static struct file_operations wandev_fops =
 	open:		wandev_open,
 	read:		seq_read,
 	llseek:		seq_lseek,
-	release:	seq_release,
+	release:	single_release,
 	ioctl:		wanrouter_ioctl,
 };