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Message-ID: <20211210132535.gy7rqj5zblqlnz5y@skn-laptop.hadsten>
Date: Fri, 10 Dec 2021 14:25:35 +0100
From: Sean Nyekjaer <sean@...nix.com>
To: Miquel Raynal <miquel.raynal@...tlin.com>
Cc: Boris Brezillon <boris.brezillon@...labora.com>,
linux-kernel@...r.kernel.org,
Marek Szyprowski <m.szyprowski@...sung.com>,
Richard Weinberger <richard@....at>,
Vignesh Raghavendra <vigneshr@...com>,
Boris Brezillon <bbrezillon@...nel.org>,
linux-mtd@...ts.infradead.org
Subject: Re: [PATCH v5 3/4] mtd: core: protect access to MTD devices while in
suspend
On Thu, Dec 09, 2021 at 03:28:11PM +0100, Miquel Raynal wrote:
> Hi Sean,
>
> sean@...nix.com wrote on Thu, 9 Dec 2021 15:07:21 +0100:
>
> > On Fri, Dec 03, 2021 at 02:39:58PM +0100, Miquel Raynal wrote:
> > > Hello,
> > >
> > > > > Fine by me, lets drop this series.
> > >
> > > FYI I've dropped the entire series from mtd/next. I'm waiting for the
> > > fix discussed below (without abusing the chip mutex ;-) ).
> >
> > Cool, looking forward to test a patch series :)
>
> Test? You mean "write"? :)
>
> Cheers,
> Miquèl
Hi Miquel,
Should we us a atomic for the suspended variable?
/Sean
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;
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