Commit f9e109a2 authored by Zhihao Cheng's avatar Zhihao Cheng Committed by Miquel Raynal
Browse files

mtd: mtdconcat: Judge callback existence based on the master 



Since commit 46b5889c("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: 46b5889c ("mtd: implement proper partition handling")
Signed-off-by: default avatarZhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: default avatarMiquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210817114857.2784825-2-chengzhihao1@huawei.com
parent 60d06079

drivers/mtd/mtdconcat.c

+19 −8
Original line number Diff line number Diff line
@@ -641,6 +641,7 @@ struct mtd_info *mtd_concat_create(struct mtd_info *subdev[], /* subdevices to c 
	int i;

	size_t size;

	struct mtd_concat *concat;

	struct mtd_info *subdev_master = NULL;

	uint32_t max_erasesize, curr_erasesize;

	int num_erase_region;

	int max_writebufsize = 0;
@@ -679,17 +680,19 @@ struct mtd_info *mtd_concat_create(struct mtd_info *subdev[], /* subdevices to c 
	concat->mtd.subpage_sft = subdev[0]->subpage_sft;

	concat->mtd.oobsize = subdev[0]->oobsize;

	concat->mtd.oobavail = subdev[0]->oobavail;

	if (subdev[0]->_writev)



	subdev_master = mtd_get_master(subdev[0]);

	if (subdev_master->_writev)

		concat->mtd._writev = concat_writev;

	if (subdev[0]->_read_oob)

	if (subdev_master->_read_oob)

		concat->mtd._read_oob = concat_read_oob;

	if (subdev[0]->_write_oob)

	if (subdev_master->_write_oob)

		concat->mtd._write_oob = concat_write_oob;

	if (subdev[0]->_block_isbad)

	if (subdev_master->_block_isbad)

		concat->mtd._block_isbad = concat_block_isbad;

	if (subdev[0]->_block_markbad)

	if (subdev_master->_block_markbad)

		concat->mtd._block_markbad = concat_block_markbad;

	if (subdev[0]->_panic_write)

	if (subdev_master->_panic_write)

		concat->mtd._panic_write = concat_panic_write;



	concat->mtd.ecc_stats.badblocks = subdev[0]->ecc_stats.badblocks;
@@ -721,14 +724,22 @@ struct mtd_info *mtd_concat_create(struct mtd_info *subdev[], /* subdevices to c 
				    subdev[i]->flags & MTD_WRITEABLE;

		}



		subdev_master = mtd_get_master(subdev[i]);

		concat->mtd.size += subdev[i]->size;

		concat->mtd.ecc_stats.badblocks +=

			subdev[i]->ecc_stats.badblocks;

		if (concat->mtd.writesize   !=  subdev[i]->writesize ||

		    concat->mtd.subpage_sft != subdev[i]->subpage_sft ||

		    concat->mtd.oobsize    !=  subdev[i]->oobsize ||

		    !concat->mtd._read_oob  != !subdev[i]->_read_oob ||

		    !concat->mtd._write_oob != !subdev[i]->_write_oob) {

		    !concat->mtd._read_oob  != !subdev_master->_read_oob ||

		    !concat->mtd._write_oob != !subdev_master->_write_oob) {

			/*

			 * Check against subdev[i] for data members, because

			 * subdev's attributes may be different from master

			 * mtd device. Check against subdev's master mtd

			 * device for callbacks, because the existence of

			 * subdev's callbacks is decided by master mtd device.

			 */

			kfree(concat);

			printk("Incompatible OOB or ECC data on \"%s\"\n",

			       subdev[i]->name);