[PATCH v2] mtd: mtdconcat: Check existence of _read|_write from subdev'master device before assigning

Zhihao Cheng
2021-08-17T03:13:10Z

Since 2431c4f5b46c3 ("mtd: Implement mtd_{read,write}() as wrappers
around mtd_{read,write}_oob()") don't allow _write|_read and
_write_oob|_read_oob existing at the same time. We should check the
existence of callbacks "_read and _write" from subdev's master device
(We can trust master device since it has been registered) before
assigning, otherwise following warning occurs while making
concatenated device:

WARNING: CPU: 2 PID: 6728 at drivers/mtd/mtdcore.c:595
add_mtd_device+0x7f/0x7b0

Fixes: 2431c4f5b46c3 ("mtd: Implement mtd_{read,write}() around ...")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
---
drivers/mtd/mtdconcat.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/mtdconcat.c b/drivers/mtd/mtdconcat.c
index af51eee6b5e8..f685a581df48 100644
--- a/drivers/mtd/mtdconcat.c
+++ b/drivers/mtd/mtdconcat.c
@@ -694,6 +694,10 @@ struct mtd_info *mtd_concat_create(struct mtd_info *subdev[], /* subdevices to c
concat->mtd._block_markbad = concat_block_markbad;
if (subdev_master->_panic_write)
concat->mtd._panic_write = concat_panic_write;
+ if (subdev_master->_read)
+ concat->mtd._read = concat_read;
+ if (subdev_master->_write)
+ concat->mtd._write = concat_write;

concat->mtd.ecc_stats.badblocks = subdev[0]->ecc_stats.badblocks;

@@ -755,8 +759,6 @@ struct mtd_info *mtd_concat_create(struct mtd_info *subdev[], /* subdevices to c
concat->mtd.name = name;

concat->mtd._erase = concat_erase;
- concat->mtd._read = concat_read;
- concat->mtd._write = concat_write;
concat->mtd._sync = concat_sync;
concat->mtd._lock = concat_lock;
concat->mtd._unlock = concat_unlock;
--
2.31.1