seq_file: fix NULL pointer arithmetic warning

Implement conditional logic in order to replace NULL pointer arithmetic.

The use of NULL pointer arithmetic was pointed out by clang with the
following warning:

fs/kernfs/file.c:128:15: warning: performing pointer arithmetic on a
null pointer has undefined behavior [-Wnull-pointer-arithmetic]
                return NULL + !*ppos;
                       ~~~~ ^
fs/seq_file.c:559:14: warning: performing pointer arithmetic on a
null pointer has undefined behavior [-Wnull-pointer-arithmetic]
        return NULL + (*pos == 0);

Signed-off-by: Maíra Canal <maira.canal@usp.br>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/seq_file.c b/fs/seq_file.c
index f8e1f4ee87ff..7ab8a58c29b6 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -554,9 +554,9 @@ int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc)
 }
 EXPORT_SYMBOL(seq_dentry);
 
-static void *single_start(struct seq_file *p, loff_t *pos)
+void *single_start(struct seq_file *p, loff_t *pos)
 {
-	return NULL + (*pos == 0);
+	return *pos ? NULL : SEQ_START_TOKEN;
 }
 
 static void *single_next(struct seq_file *p, void *v, loff_t *pos)