mtd: mtdconcat: fix bug with uninitialized lock and unlock functions

Test if a lock or unlock function is present (pointer not NULL) before
calling it, to prevent a kernel dump.

Artem: removed extra blank lines

Signed-off-by: Martin Krause <martin.krause@tqs.de>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 12 insertions, 8 deletions

diff --git a/drivers/mtd/mtdconcat.c b/drivers/mtd/mtdconcat.c
index 7e075621bbf4..4567bc373780 100644
--- a/drivers/mtd/mtdconcat.c
+++ b/drivers/mtd/mtdconcat.c
@@ -540,10 +540,12 @@ static int concat_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
                 else
                         size = len;
 
-                err = subdev->lock(subdev, ofs, size);
-
-                if (err)
-                        break;
+                if (subdev->lock) {
+                        err = subdev->lock(subdev, ofs, size);
+                        if (err)
+                                break;
+                } else
+                        err = -EOPNOTSUPP;
 
                 len -= size;
                 if (len == 0)
@@ -578,10 +580,12 @@ static int concat_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
                 else
                         size = len;
 
-                err = subdev->unlock(subdev, ofs, size);
-
-                if (err)
-                        break;
+                if (subdev->unlock) {
+                        err = subdev->unlock(subdev, ofs, size);
+                        if (err)
+                                break;
+                } else
+                        err = -EOPNOTSUPP;
 
                 len -= size;
                 if (len == 0)