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Message-ID: <20211020105743.225d97f4@collabora.com>
Date: Wed, 20 Oct 2021 10:57:43 +0200
From: Boris Brezillon <boris.brezillon@...labora.com>
To: Sean Nyekjaer <sean@...nix.com>
Cc: Miquel Raynal <miquel.raynal@...tlin.com>,
Richard Weinberger <richard@....at>,
Vignesh Raghavendra <vigneshr@...com>,
Boris Brezillon <bbrezillon@...nel.org>,
linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/4] mtd: rawnand: remove suspended check
On Wed, 20 Oct 2021 10:45:33 +0200
Sean Nyekjaer <sean@...nix.com> wrote:
> Access is protected in upper MTD layer when MTD devices are suspended.
I think it deserves more explanation.
>
> Fixes: 013e6292aaf5 ("mtd: rawnand: Simplify the locking")
This patch doesn't fix anything, things have been fixed in 'mtd: core:
protect access to MTD devices while in suspend'. It's just a cleanup on
top of it.
> Reviewed-by: Miquel Raynal <miquel.raynal@...tlin.com>
> Signed-off-by: Sean Nyekjaer <sean@...nix.com>
> ---
> drivers/mtd/nand/raw/nand_base.c | 52 ++++++++------------------------
> include/linux/mtd/rawnand.h | 5 +--
> 2 files changed, 14 insertions(+), 43 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index 3d6c6e880520..aa2874ae3c4a 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -332,19 +332,11 @@ static int nand_isbad_bbm(struct nand_chip *chip, loff_t ofs)
> * @chip: NAND chip structure
> *
> * Lock the device and its controller for exclusive access
> - *
> - * 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) {
> - mutex_unlock(&chip->lock);
> - return -EBUSY;
> - }
> mutex_lock(&chip->controller->lock);
> -
> - return 0;
> }
>
> /**
> @@ -573,10 +565,7 @@ 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);
> }
> @@ -3756,9 +3745,7 @@ 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);
> @@ -4345,13 +4332,11 @@ 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:
> @@ -4410,10 +4395,8 @@ int nand_erase_nand(struct nand_chip *chip, struct erase_info *instr,
> if (nand_region_is_secured(chip, instr->addr, instr->len))
> return -EIO;
>
> - /* Grab the lock and see if the device is available */
> - ret = nand_get_device(chip);
> - if (ret)
> - return ret;
> + /* Grab the lock */
> + nand_get_device(chip);
>
> /* Shift to get first page */
> page = (int)(instr->addr >> chip->page_shift);
> @@ -4499,8 +4482,8 @@ 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));
> + /* Grab the lock */
> + nand_get_device(chip);
> /* Release it and go back */
> nand_release_device(chip);
> }
> @@ -4517,9 +4500,7 @@ 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);
>
> @@ -4565,8 +4546,6 @@ static int nand_suspend(struct mtd_info *mtd)
> mutex_lock(&chip->lock);
> if (chip->ops.suspend)
> ret = chip->ops.suspend(chip);
> - if (!ret)
> - chip->suspended = 1;
> mutex_unlock(&chip->lock);
>
> return ret;
> @@ -4580,15 +4559,10 @@ static void nand_resume(struct mtd_info *mtd)
> {
> struct nand_chip *chip = mtd_to_nand(mtd);
>
> +
> mutex_lock(&chip->lock);
> - if (chip->suspended) {
> - if (chip->ops.resume)
> - chip->ops.resume(chip);
> - chip->suspended = 0;
> - } else {
> - pr_err("%s called for a chip which is not in suspended state\n",
> - __func__);
> - }
> + if (chip->ops.resume)
> + chip->ops.resume(chip);
> mutex_unlock(&chip->lock);
> }
>
> diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
> index b2f9dd3cbd69..1198a6548912 100644
> --- a/include/linux/mtd/rawnand.h
> +++ b/include/linux/mtd/rawnand.h
> @@ -1237,9 +1237,7 @@ struct nand_secure_region {
> * @pagecache.page: Page number currently in the cache. -1 means no page is
> * currently cached
> * @buf_align: Minimum buffer alignment required by a platform
> - * @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
> + * @lock: Lock to serialize accesses to the NAND device
> * @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
> @@ -1293,7 +1291,6 @@ struct nand_chip {
>
> /* Internals */
> struct mutex lock;
> - unsigned int suspended : 1;
> int cur_cs;
> int read_retries;
> struct nand_secure_region *secure_regions;
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