mtd_blkdevs: remove blktrans_ref_mutex

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>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210823073359.705281-7-hch@lst.de

diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index eb15a84cb6500dc51257a6b0228aab18a246c275..84bcad1b740898045494b4086c781e377d3afe28 100644 (file)
--- 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);