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From: Christoph Hellwig <hch@lst.de>
To: Miquel Raynal <miquel.raynal@bootlin.com>,
	Richard Weinberger <richard@nod.at>,
	Vignesh Raghavendra <vigneshr@ti.com>
Cc: Guenter Roeck <linux@roeck-us.net>, linux-mtd@lists.infradead.org
Subject: [PATCH 6/8] mtd_blkdevs: remove blktrans_ref_mutex
Date: Mon, 23 Aug 2021 09:33:57 +0200	[thread overview]
Message-ID: <20210823073359.705281-7-hch@lst.de> (raw)
In-Reply-To: <20210823073359.705281-1-hch@lst.de>

blktrans_ref_mutex is not actually needed.  The kref is serialized
internally, and devnum assignment in add_mtd_blktrans_dev happens before
the disk is added and thus any of the block_device_operations methods
otherwise using it are called.  It  is also already serialized by the
global mtd_table_mutex.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/mtd/mtd_blkdevs.c | 13 +------------
 1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index f5e13b919614..6f226b7cbb5c 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -23,7 +23,6 @@
 #include "mtdcore.h"
 
 static LIST_HEAD(blktrans_majors);
-static DEFINE_MUTEX(blktrans_ref_mutex);
 
 static void blktrans_dev_release(struct kref *kref)
 {
@@ -41,18 +40,13 @@ static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk)
 {
 	struct mtd_blktrans_dev *dev = disk->private_data;
 
-	mutex_lock(&blktrans_ref_mutex);
 	kref_get(&dev->ref);
-	mutex_unlock(&blktrans_ref_mutex);
-
 	return dev;
 }
 
 static void blktrans_dev_put(struct mtd_blktrans_dev *dev)
 {
-	mutex_lock(&blktrans_ref_mutex);
 	kref_put(&dev->ref, blktrans_dev_release);
-	mutex_unlock(&blktrans_ref_mutex);
 }
 
 
@@ -299,7 +293,6 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 
 	lockdep_assert_held(&mtd_table_mutex);
 
-	mutex_lock(&blktrans_ref_mutex);
 	list_for_each_entry(d, &tr->devs, list) {
 		if (new->devnum == -1) {
 			/* Use first free number */
@@ -311,7 +304,6 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 			}
 		} else if (d->devnum == new->devnum) {
 			/* Required number taken */
-			mutex_unlock(&blktrans_ref_mutex);
 			return -EBUSY;
 		} else if (d->devnum > new->devnum) {
 			/* Required number was free */
@@ -329,14 +321,11 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 	 * minor numbers and that the disk naming code below can cope
 	 * with this number. */
 	if (new->devnum > (MINORMASK >> tr->part_bits) ||
-	    (tr->part_bits && new->devnum >= 27 * 26)) {
-		mutex_unlock(&blktrans_ref_mutex);
+	    (tr->part_bits && new->devnum >= 27 * 26))
 		return ret;
-	}
 
 	list_add_tail(&new->list, &tr->devs);
  added:
-	mutex_unlock(&blktrans_ref_mutex);
 
 	mutex_init(&new->lock);
 	kref_init(&new->ref);
-- 
2.30.2


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  parent reply	other threads:[~2021-08-23  7:39 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-23  7:33 mtd locking fix and cleanups Christoph Hellwig
2021-08-23  7:33 ` [PATCH 1/8] mtd_blkdevs: don't hold del_mtd_blktrans_dev in blktrans_{open, release} Christoph Hellwig
2021-08-23  8:33   ` Miquel Raynal
2021-08-23  7:33 ` [PATCH 2/8] mtd_blkdevs: use lockdep_assert_held Christoph Hellwig
2021-08-23  8:33   ` Miquel Raynal
2021-08-23  7:33 ` [PATCH 3/8] mtd/ftl: don't cast away the type when calling add_mtd_blktrans_dev Christoph Hellwig
2021-08-23  8:33   ` Miquel Raynal
2021-08-23  7:33 ` [PATCH 4/8] mtd/rfd_ftl: " Christoph Hellwig
2021-08-23  8:33   ` Miquel Raynal
2021-08-23  7:33 ` [PATCH 5/8] mtd_blkdevs: simplify blktrans_dev_get Christoph Hellwig
2021-08-23  8:33   ` Miquel Raynal
2021-08-23  7:33 ` Christoph Hellwig [this message]
2021-08-23  8:33   ` [PATCH 6/8] mtd_blkdevs: remove blktrans_ref_mutex Miquel Raynal
2021-08-23  7:33 ` [PATCH 7/8] mtd_blkdevs: simplify blktrans_getgeo Christoph Hellwig
2021-08-23  8:33   ` Miquel Raynal
2021-08-23  7:33 ` [PATCH 8/8] mtd_blkdevs: simplify the refcounting in blktrans_{open, release} Christoph Hellwig
2021-08-23  8:33   ` Miquel Raynal
2021-08-23  8:30 ` mtd locking fix and cleanups Miquel Raynal

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