[PATCH 1/1] cio_ignore_proc_seq_next should increase position index

[Vasily Averin <vvs@xxxxxxxxxxxxx>]

if seq_file .next fuction does not change position index,
read after some lseek can generate unexpected output.

https://bugzilla.kernel.org/show_bug.cgi?id=206283
Signed-off-by: Vasily Averin <vvs@xxxxxxxxxxxxx>
---
 drivers/s390/cio/blacklist.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/s390/cio/blacklist.c b/drivers/s390/cio/blacklist.c
index 2a3f874..9cebff8 100644
--- a/drivers/s390/cio/blacklist.c
+++ b/drivers/s390/cio/blacklist.c
@@ -303,8 +303,10 @@ struct ccwdev_iter {
 cio_ignore_proc_seq_next(struct seq_file *s, void *it, loff_t *offset)
 {
 	struct ccwdev_iter *iter;
+	loff_t p = *offset;
 
-	if (*offset >= (__MAX_SUBCHANNEL + 1) * (__MAX_SSID + 1))
+	(*offset)++;
+	if (p >= (__MAX_SUBCHANNEL + 1) * (__MAX_SSID + 1))
 		return NULL;
 	iter = it;
 	if (iter->devno == __MAX_SUBCHANNEL) {
@@ -314,7 +316,6 @@ struct ccwdev_iter {
 			return NULL;
 	} else
 		iter->devno++;
-	(*offset)++;
 	return iter;
 }
 
-- 
1.8.3.1