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Subject[PATCH v3 1/4] mtd: rawnand: nand_bbt: hide suspend/resume hooks while scanning bbt
Date
From: Boris Brezillon <boris.brezillon@collabora.com>

The BBT scan logic use the MTD helpers before the MTD layer had a
chance to initialize the device, and that leads to issues when
accessing the uninitialized suspend lock. Let's temporarily set the
suspend/resume hooks to NULL to skip the lock acquire/release step.

Fixes: 013e6292aaf5 ("mtd: rawnand: Simplify the locking")
Tested-by: Sean Nyekjaer <sean@geanix.com>
---
drivers/mtd/nand/raw/nand_bbt.c | 28 +++++++++++++++++++++++++++-
1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/raw/nand_bbt.c b/drivers/mtd/nand/raw/nand_bbt.c
index b7ad030225f8..93d385703469 100644
--- a/drivers/mtd/nand/raw/nand_bbt.c
+++ b/drivers/mtd/nand/raw/nand_bbt.c
@@ -1397,8 +1397,28 @@ static int nand_create_badblock_pattern(struct nand_chip *this)
*/
int nand_create_bbt(struct nand_chip *this)
{
+ struct mtd_info *mtd = nand_to_mtd(this);
+ int (*suspend) (struct mtd_info *) = mtd->_suspend;
+ void (*resume) (struct mtd_info *) = mtd->_resume;
int ret;

+ /*
+ * The BBT scan logic use the MTD helpers before the MTD layer had a
+ * chance to initialize the device, and that leads to issues when
+ * accessing the uninitialized suspend lock. Let's temporarily set the
+ * suspend/resume hooks to NULL to skip the lock acquire/release step.
+ *
+ * FIXME: This is an ugly hack, so please don't copy this pattern to
+ * other MTD implementations. The proper fix would be to implement a
+ * generic BBT scan logic at the NAND level that's not using any of the
+ * MTD helpers to access pages. We also might consider doing a two
+ * step initialization at the MTD level (mtd_device_init() +
+ * mtd_device_register()) so some of the fields are initialized
+ * early.
+ */
+ mtd->_suspend = NULL;
+ mtd->_resume = NULL;
+
/* Is a flash based bad block table requested? */
if (this->bbt_options & NAND_BBT_USE_FLASH) {
/* Use the default pattern descriptors */
@@ -1422,7 +1442,13 @@ int nand_create_bbt(struct nand_chip *this)
return ret;
}

- return nand_scan_bbt(this, this->badblock_pattern);
+ ret = nand_scan_bbt(this, this->badblock_pattern);
+
+ /* Restore the suspend/resume hooks. */
+ mtd->_suspend = suspend;
+ mtd->_resume = resume;
+
+ return ret;
}
EXPORT_SYMBOL(nand_create_bbt);

--
2.33.0
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