Prevent rawnend access while in a suspended state.

Commit 013e6292aaf5 ("mtd: rawnand: Simplify the locking") allows the rawnand layer to return errors rather than waiting in a blocking wait.

Tested on a iMX6ULL.

Fixes: 013e6292aaf5 ("mtd: rawnand: Simplify the locking") Signed-off-by: Sean Nyekjaer sean@geanix.com Reviewed-by: Boris Brezillon boris.brezillon@collabora.com --- Follow-up on discussion in: https://lkml.org/lkml/2021/10/4/41 https://lkml.org/lkml/2021/10/11/435 https://lkml.org/lkml/2021/10/20/184 https://lkml.org/lkml/2021/10/25/288 https://lkml.org/lkml/2021/10/26/55 https://lkml.org/lkml/2021/11/2/352

Changes since v1: - fixed uninitialized return

Changes since v2: - fixed wait queue description

drivers/mtd/nand/raw/nand_base.c | 44 +++++++++++++++----------------- include/linux/mtd/rawnand.h | 2 ++ 2 files changed, 22 insertions(+), 24 deletions(-)

diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c index e7b2ba016d8c..8daaba96edb2 100644 --- a/drivers/mtd/nand/raw/nand_base.c +++ b/drivers/mtd/nand/raw/nand_base.c @@ -338,16 +338,19 @@ static int nand_isbad_bbm(struct nand_chip *chip, loff_t ofs) * * Return: -EBUSY if the chip has been suspended, 0 otherwise */ -static int nand_get_device(struct nand_chip *chip) +static void nand_get_device(struct nand_chip *chip) { - mutex_lock(&chip->lock); - if (chip->suspended) { + /* Wait until the device is resumed. */ + while (1) { + mutex_lock(&chip->lock); + if (!chip->suspended) { + mutex_lock(&chip->controller->lock); + return; + } mutex_unlock(&chip->lock); - return -EBUSY; - } - mutex_lock(&chip->controller->lock);

- return 0; + wait_event(chip->resume_wq, !chip->suspended); + } }

/** @@ -576,9 +579,7 @@ static int nand_block_markbad_lowlevel(struct nand_chip *chip, loff_t ofs) nand_erase_nand(chip, &einfo, 0);

/* Write bad block marker to OOB */ - ret = nand_get_device(chip); - if (ret) - return ret; + nand_get_device(chip);

ret = nand_markbad_bbm(chip, ofs); nand_release_device(chip); @@ -3826,9 +3827,7 @@ static int nand_read_oob(struct mtd_info *mtd, loff_t from, ops->mode != MTD_OPS_RAW) return -ENOTSUPP;

- ret = nand_get_device(chip); - if (ret) - return ret; + nand_get_device(chip);

if (!ops->datbuf) ret = nand_do_read_oob(chip, from, ops); @@ -4415,13 +4414,11 @@ static int nand_write_oob(struct mtd_info *mtd, loff_t to, struct mtd_oob_ops *ops) { struct nand_chip *chip = mtd_to_nand(mtd); - int ret; + int ret = 0;

ops->retlen = 0;

- ret = nand_get_device(chip); - if (ret) - return ret; + nand_get_device(chip);

switch (ops->mode) { case MTD_OPS_PLACE_OOB: @@ -4481,9 +4478,7 @@ int nand_erase_nand(struct nand_chip *chip, struct erase_info *instr, return -EIO;

/* Grab the lock and see if the device is available */ - ret = nand_get_device(chip); - if (ret) - return ret; + nand_get_device(chip);

/* Shift to get first page */ page = (int)(instr->addr >> chip->page_shift); @@ -4570,7 +4565,7 @@ static void nand_sync(struct mtd_info *mtd) pr_debug("%s: called\n", __func__);

/* Grab the lock and see if the device is available */ - WARN_ON(nand_get_device(chip)); + nand_get_device(chip); /* Release it and go back */ nand_release_device(chip); } @@ -4587,9 +4582,7 @@ static int nand_block_isbad(struct mtd_info *mtd, loff_t offs) int ret;

/* Select the NAND device */ - ret = nand_get_device(chip); - if (ret) - return ret; + nand_get_device(chip);

nand_select_target(chip, chipnr);

@@ -4660,6 +4653,8 @@ static void nand_resume(struct mtd_info *mtd) __func__); } mutex_unlock(&chip->lock); + + wake_up_all(&chip->resume_wq); }

/** @@ -5437,6 +5432,7 @@ static int nand_scan_ident(struct nand_chip *chip, unsigned int maxchips, chip->cur_cs = -1;

mutex_init(&chip->lock); + init_waitqueue_head(&chip->resume_wq);

/* Enforce the right timings for reset/detection */ chip->current_interface_config = nand_get_reset_interface_config(); diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h index 5b88cd51fadb..dcf90144d70b 100644 --- a/include/linux/mtd/rawnand.h +++ b/include/linux/mtd/rawnand.h @@ -1240,6 +1240,7 @@ struct nand_secure_region { * @lock: Lock protecting the suspended field. Also used to serialize accesses * to the NAND device * @suspended: Set to 1 when the device is suspended, 0 when it's not + * @resume_wq: wait queue to sleep if rawnand is in suspended state. * @cur_cs: Currently selected target. -1 means no target selected, otherwise we * should always have cur_cs >= 0 && cur_cs < nanddev_ntargets(). * NAND Controller drivers should not modify this value, but they're @@ -1294,6 +1295,7 @@ struct nand_chip { /* Internals */ struct mutex lock; unsigned int suspended : 1; + wait_queue_head_t resume_wq; int cur_cs; int read_retries; struct nand_secure_region *secure_regions;