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From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Zhihao Cheng <chengzhihao1@huawei.com>,
	miquel.raynal@bootlin.com, richard@nod.at, vigneshr@ti.com,
	bbrezillon@kernel.org
Cc: linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org,
	yukuai3@huawei.com
Subject: Re: [PATCH v2 1/2] mtd: mtdconcat: Judge callback existence based on the master
Date: Tue, 17 Aug 2021 18:49:18 +0200	[thread overview]
Message-ID: <20210817164918.108904-1-miquel.raynal@bootlin.com> (raw)
In-Reply-To: <20210817114857.2784825-2-chengzhihao1@huawei.com>

On Tue, 2021-08-17 at 11:48:56 UTC, Zhihao Cheng wrote:
> Since commit 46b5889cc2c5("mtd: implement proper partition handling")
> applied, mtd partition device won't hold some callback functions, such
> as _block_isbad, _block_markbad, etc. Besides, function mtd_block_isbad()
> will get mtd device's master mtd device, then invokes master mtd device's
> callback function. So, following process may result mtd_block_isbad()
> always return 0, even though mtd device has bad blocks:
> 
> 1. Split a mtd device into 3 partitions: PA, PB, PC
> [ Each mtd partition device won't has callback function _block_isbad(). ]
> 2. Concatenate PA and PB as a new mtd device PN
> [ mtd_concat_create() finds out each subdev has no callback function
> _block_isbad(), so PN won't be assigned callback function
> concat_block_isbad(). ]
> Then, mtd_block_isbad() checks "!master->_block_isbad" is true, will
> always return 0.
> 
> Reproducer:
> // reproduce.c
> static int __init init_diy_module(void)
> {
> 	struct mtd_info *mtd[2];
> 	struct mtd_info *mtd_combine = NULL;
> 
> 	mtd[0] = get_mtd_device_nm("NAND simulator partition 0");
> 	if (!mtd[0]) {
> 		pr_err("cannot find mtd1\n");
> 		return -EINVAL;
> 	}
> 	mtd[1] = get_mtd_device_nm("NAND simulator partition 1");
> 	if (!mtd[1]) {
> 		pr_err("cannot find mtd2\n");
> 		return -EINVAL;
> 	}
> 
> 	put_mtd_device(mtd[0]);
> 	put_mtd_device(mtd[1]);
> 
> 	mtd_combine = mtd_concat_create(mtd, 2, "Combine mtd");
> 	if (mtd_combine == NULL) {
> 		pr_err("combine failed\n");
> 		return -EINVAL;
> 	}
> 
> 	mtd_device_register(mtd_combine, NULL, 0);
> 	pr_info("Combine success\n");
> 
> 	return 0;
> }
> 
> 1. ID="0x20,0xac,0x00,0x15"
> 2. modprobe nandsim id_bytes=$ID parts=50,100 badblocks=100
> 3. insmod reproduce.ko
> 4. flash_erase /dev/mtd3 0 0
>   libmtd: error!: MEMERASE64 ioctl failed for eraseblock 100 (mtd3)
>   error 5 (Input/output error)
>   // Should be "flash_erase: Skipping bad block at 00c80000"
> 
> Fixes: 46b5889cc2c54bac ("mtd: implement proper partition handling")
> Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/next, thanks.

Miquel

  reply	other threads:[~2021-08-17 16:49 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-17 11:48 [PATCH v2 0/2] mtd: mtdconcat: Fix callback functions check Zhihao Cheng
2021-08-17 11:48 ` [PATCH v2 1/2] mtd: mtdconcat: Judge callback existence based on the master Zhihao Cheng
2021-08-17 16:49   ` Miquel Raynal [this message]
2021-08-17 11:48 ` [PATCH v2 2/2] mtd: mtdconcat: Check _read,_write callbacks existence before assignment Zhihao Cheng
2021-08-17 16:49   ` [PATCH v2 2/2] mtd: mtdconcat: Check _read, _write " Miquel Raynal

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