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Subject[PATCH] mtd: rawnand: protect access to rawnand devices while in suspend
Date
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>
---
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

drivers/mtd/nand/raw/nand_base.c | 42 +++++++++++++++-----------------
include/linux/mtd/rawnand.h | 1 +
2 files changed, 20 insertions(+), 23 deletions(-)

diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index b3a9bc08b4bb..eb4ec9a42d49 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);
@@ -3759,9 +3760,7 @@ 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);
@@ -4352,9 +4351,7 @@ static int nand_write_oob(struct mtd_info *mtd, loff_t to,

ops->retlen = 0;

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

switch (ops->mode) {
case MTD_OPS_PLACE_OOB:
@@ -4414,9 +4411,7 @@ 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);
@@ -4503,7 +4498,7 @@ 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);
}
@@ -4520,9 +4515,7 @@ 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);

@@ -4593,6 +4586,8 @@ static void nand_resume(struct mtd_info *mtd)
__func__);
}
mutex_unlock(&chip->lock);
+
+ wake_up_all(&chip->resume_wq);
}

/**
@@ -5370,6 +5365,7 @@ 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 b2f9dd3cbd69..248054560581 100644
--- a/include/linux/mtd/rawnand.h
+++ b/include/linux/mtd/rawnand.h
@@ -1294,6 +1294,7 @@ 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;
--
2.34.1
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