linux-kernel - [PATCH 5.16 0079/1017] mtd: rawnand: protect access to rawnand devices while in suspend

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Message-Id: <20220405070356.536320799@linuxfoundation.org>
Date:   Tue,  5 Apr 2022 09:16:32 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Sean Nyekjaer <sean@...nix.com>,
        Boris Brezillon <boris.brezillon@...labora.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>
Subject: [PATCH 5.16 0079/1017] mtd: rawnand: protect access to rawnand devices while in suspend

From: Sean Nyekjaer <sean@...nix.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@...nix.com>
Reviewed-by: Boris Brezillon <boris.brezillon@...labora.com>
Cc: stable@...r.kernel.org
Signed-off-by: Miquel Raynal <miquel.raynal@...tlin.com>
Link: https://lore.kernel.org/linux-mtd/20220208085213.1838273-1-sean@geanix.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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
@@ -335,16 +335,19 @@ 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);
+	}
 }
 
 /**
@@ -573,9 +576,7 @@ 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);
@@ -3823,9 +3824,7 @@ 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);
@@ -4412,13 +4411,11 @@ 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:
@@ -4478,9 +4475,7 @@ 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);
@@ -4567,7 +4562,7 @@ 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);
 }
@@ -4584,9 +4579,7 @@ 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);
 
@@ -4657,6 +4650,8 @@ static void nand_resume(struct mtd_info
 			__func__);
 	}
 	mutex_unlock(&chip->lock);
+
+	wake_up_all(&chip->resume_wq);
 }
 
 /**
@@ -5434,6 +5429,7 @@ 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;