From 23986a85b9efe7bc3ffc0887b8d17cdf2fbab4f2 Mon Sep 17 00:00:00 2001
From: Arun KS <arun.ks@broadcom.com>
Date: Mon, 19 Aug 2013 12:06:33 +0530
Subject: SeqFile: Fix overflow condition

seq_path()/seq_commit() is treating a d_path() failure as an overflow
condition, but it isn't.

Signed-off-by: Arun KS <arun.ks@broadcom.com>
---
 fs/seq_file.c            |  6 +++---
 include/linux/seq_file.h | 11 ++++++-----
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/fs/seq_file.c b/fs/seq_file.c
index 3135c25..6a33f9c 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -463,7 +463,7 @@ int seq_path(struct seq_file *m, const struct path *path, const char *esc)
 {
 	char *buf;
 	size_t size = seq_get_buf(m, &buf);
-	int res = -1;
+	int res = -ENOBUFS;
 
 	if (size) {
 		char *p = d_path(path, buf, size);
@@ -487,7 +487,7 @@ int seq_path_root(struct seq_file *m, const struct path *path,
 {
 	char *buf;
 	size_t size = seq_get_buf(m, &buf);
-	int res = -ENAMETOOLONG;
+	int res = -ENOBUFS;
 
 	if (size) {
 		char *p;
@@ -516,7 +516,7 @@ int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc)
 {
 	char *buf;
 	size_t size = seq_get_buf(m, &buf);
-	int res = -1;
+	int res = -ENOBUFS;
 
 	if (size) {
 		char *p = dentry_path(dentry, buf, size);
diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h
index 4e32edc..7bfb540 100644
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -66,16 +66,17 @@ static inline size_t seq_get_buf(struct seq_file *m, char **bufp)
  * @num: the number of bytes to commit
  *
  * Commit @num bytes of data written to a buffer previously acquired
- * by seq_buf_get.  To signal an error condition, or that the data
- * didn't fit in the available space, pass a negative @num value.
+ * by seq_buf_get.  To signal an overflow condition(data didn't fit
+ * in the available space), pass -ENOBUFS and for other errors pass a
+ * negative @num value.
  */
 static inline void seq_commit(struct seq_file *m, int num)
 {
-	if (num < 0) {
-		m->count = m->size;
-	} else {
+	if (num >= 0) {
 		BUG_ON(m->count + num > m->size);
 		m->count += num;
+	} else if (num == -ENOBUFS)
+		m->count = m->size;
 	}
 }
 
-- 
1.8.2