[PATCH 5.17 0069/1126] mtd: rawnand: protect access to rawnand devices while in suspend

Greg Kroah-Hartman
2022-04-05T08:00:34Z

From: Sean Nyekjaer <sean@geanix.com>

commit 8cba323437a49a45756d661f500b324fc2d486fe upstream.

Prevent rawnand 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>
Cc: stable@vger.kernel.org
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220208085213.1838273-1-sean@geanix.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/mtd/nand/raw/nand_base.c | 44 +++++++++++++++++----------------------
include/linux/mtd/rawnand.h | 2 +
2 files changed, 22 insertions(+), 24 deletions(-)

--- 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_ch
*
* 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(s
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
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_inf
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 *ch
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 *m
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_i
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
__func__);
}
mutex_unlock(&chip->lock);
+
+ wake_up_all(&chip->resume_wq);
}

/**
@@ -5437,6 +5432,7 @@ static int nand_scan_ident(struct nand_c
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();
--- 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;