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

Zhihao Cheng
2021-08-17T03:17:38Z

在 2021/8/17 10:45, Zhihao Cheng 写道:
Hi Miquel,
I found a better way to fix the "WARNING" on _read|_read_oob checking.
Since sub-mtd device has been registered successfully, we can check
against the existence of _read|_read_oob callbacks by subdev's master
device.
BTW, fix missing space between the SHA1 and the subject suggested by
Stephen.
> 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;