1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index e488cf910914..7cd56d2b9419 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -381,6 +381,8 @@ static inline int mtd_write_user_prot_reg(struct mtd_info *mtd, loff_t to,
                                           u_char *buf)
 {
         *retlen = 0;
+        if (!mtd->write_user_prot_reg)
+                return -EOPNOTSUPP;
         return mtd->write_user_prot_reg(mtd, to, len, retlen, buf);
 }