[PATCH -next] mtd: fix missing unlock on error in mtdchar_compat_ioctl()

[Wei Yongjun]

Add the missing unlock before return from function mtdchar_compat_ioctl()
in the error handling case.

Fixes: 210bec567936 ("mtd: properly check all write ioctls for permissions")
Reported-by: Hulk Robot <hul...@huawei.com>
Signed-off-by: Wei Yongjun <weiyongj...@huawei.com>
---
 drivers/mtd/mtdchar.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index 52c120f9fb0d..b40f46a43fc6 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -1064,8 +1064,10 @@ static long mtdchar_compat_ioctl(struct file *file, 
unsigned int cmd,
                struct mtd_oob_buf32 buf;
                struct mtd_oob_buf32 __user *buf_user = argp;
 
-               if (!(file->f_mode & FMODE_WRITE))
-                       return -EPERM;
+               if (!(file->f_mode & FMODE_WRITE)) {
+                       ret = -EPERM;
+                       break;
+               }
 
                if (copy_from_user(&buf, argp, sizeof(buf)))
                        ret = -EFAULT;