proc: use single_open() correctly

single_open()'s third argument is for copying into seq_file->private.  Use
that, rather than open-coding it.

Signed-off-by: Jovi Zhang <bookjovi@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/base.c

@@ -745,14 +745,7 @@ static int proc_single_show(struct seq_file *m, void *v)
 
 static int proc_single_open(struct inode *inode, struct file *filp)
 {
-	int ret;
-	ret = single_open(filp, proc_single_show, NULL);
-	if (!ret) {
-		struct seq_file *m = filp->private_data;
-
-		m->private = inode;
-	}
-	return ret;
+	return single_open(filp, proc_single_show, inode);
 }
 
 static const struct file_operations proc_single_file_operations = {
@@ -1380,15 +1373,7 @@ sched_write(struct file *file, const char __user *buf,
 
 static int sched_open(struct inode *inode, struct file *filp)
 {
-	int ret;
-
-	ret = single_open(filp, sched_show, NULL);
-	if (!ret) {
-		struct seq_file *m = filp->private_data;
-
-		m->private = inode;
-	}
-	return ret;
+	return single_open(filp, sched_show, inode);
 }
 
 static const struct file_operations proc_pid_sched_operations = {
@@ -1524,15 +1509,7 @@ static int comm_show(struct seq_file *m, void *v)
 
 static int comm_open(struct inode *inode, struct file *filp)
 {
-	int ret;
-
-	ret = single_open(filp, comm_show, NULL);
-	if (!ret) {
-		struct seq_file *m = filp->private_data;
-
-		m->private = inode;
-	}
-	return ret;
+	return single_open(filp, comm_show, inode);
 }
 
 static const struct file_operations proc_pid_set_comm_operations = {