Messages in this thread Patch in this message | | | Date | Fri, 9 Sep 2022 16:36:20 +0200 | From | ChristophHellwig <> | Subject | Re: [PATCH] mtd_blkdevs: add mtd_table_mutex lock back to blktrans_{open, release} to avoid race condition |
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Can you try this patch (it'll need to be split up into a few if it works):
diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c index 60b222799871e..9eda1dd98a406 100644 --- a/drivers/mtd/mtd_blkdevs.c +++ b/drivers/mtd/mtd_blkdevs.c @@ -24,24 +24,16 @@ static LIST_HEAD(blktrans_majors); -static void blktrans_dev_release(struct kref *kref) +static void blktrans_free_disk(struct gendisk *disk) { - struct mtd_blktrans_dev *dev = - container_of(kref, struct mtd_blktrans_dev, ref); + struct mtd_blktrans_dev *dev = disk->private_data; - put_disk(dev->disk); blk_mq_free_tag_set(dev->tag_set); kfree(dev->tag_set); list_del(&dev->list); kfree(dev); } -static void blktrans_dev_put(struct mtd_blktrans_dev *dev) -{ - kref_put(&dev->ref, blktrans_dev_release); -} - - static blk_status_t do_blktrans_request(struct mtd_blktrans_ops *tr, struct mtd_blktrans_dev *dev, struct request *req) @@ -187,63 +179,58 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode) struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data; int ret = 0; - kref_get(&dev->ref); + if (disk_openers(bdev->bd_disk) > 0) + return 0; - mutex_lock(&dev->lock); - - if (dev->open) - goto unlock; + mutex_lock(&mtd_table_mutex); + if (!dev->mtd) { + mutex_lock(&mtd_table_mutex); + return -EINVAL; + } + ret = __get_mtd_device(dev->mtd); + mutex_unlock(&mtd_table_mutex); + if (ret) + return ret; + mutex_lock(&dev->lock); __module_get(dev->tr->owner); - - if (!dev->mtd) - goto unlock; - if (dev->tr->open) { ret = dev->tr->open(dev); if (ret) goto error_put; } - - ret = __get_mtd_device(dev->mtd); - if (ret) - goto error_release; dev->file_mode = mode; - -unlock: dev->open++; mutex_unlock(&dev->lock); - return ret; -error_release: - if (dev->tr->release) - dev->tr->release(dev); + return 0; + error_put: module_put(dev->tr->owner); mutex_unlock(&dev->lock); - blktrans_dev_put(dev); + + put_mtd_device(dev->mtd); return ret; } static void blktrans_release(struct gendisk *disk, fmode_t mode) { struct mtd_blktrans_dev *dev = disk->private_data; + struct mtd_info *mtd = NULL; - mutex_lock(&dev->lock); - - if (--dev->open) - goto unlock; + if (disk_openers(disk) > 0) + return; + mutex_lock(&dev->lock); + dev->open--; module_put(dev->tr->owner); - - if (dev->mtd) { - if (dev->tr->release) - dev->tr->release(dev); - __put_mtd_device(dev->mtd); - } -unlock: + mtd = dev->mtd; + if (mtd && dev->tr->release) + dev->tr->release(dev); mutex_unlock(&dev->lock); - blktrans_dev_put(dev); + + if (mtd) + put_mtd_device(dev->mtd); } static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo) @@ -266,6 +253,7 @@ static const struct block_device_operations mtd_block_ops = { .owner = THIS_MODULE, .open = blktrans_open, .release = blktrans_release, + .free_disk = blktrans_free_disk, .getgeo = blktrans_getgeo, }; @@ -318,7 +306,6 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new) added: mutex_init(&new->lock); - kref_init(&new->ref); if (!tr->writesect) new->readonly = 1; @@ -410,6 +397,7 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new) int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old) { + struct mtd_info *old_mtd = NULL; unsigned long flags; lockdep_assert_held(&mtd_table_mutex); @@ -438,13 +426,14 @@ int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old) if (old->open) { if (old->tr->release) old->tr->release(old); - __put_mtd_device(old->mtd); + old_mtd = old->mtd; } - old->mtd = NULL; - mutex_unlock(&old->lock); - blktrans_dev_put(old); + put_disk(old->disk); + + if (old->mtd) + put_mtd_device(old_mtd); return 0; } diff --git a/include/linux/mtd/blktrans.h b/include/linux/mtd/blktrans.h index 15cc9b95e32b5..41a81fc9f0462 100644 --- a/include/linux/mtd/blktrans.h +++ b/include/linux/mtd/blktrans.h @@ -7,7 +7,6 @@ #define __MTD_TRANS_H__ #include <linux/mutex.h> -#include <linux/kref.h> #include <linux/sysfs.h> struct hd_geometry; @@ -26,7 +25,6 @@ struct mtd_blktrans_dev { unsigned long size; int readonly; int open; - struct kref ref; struct gendisk *disk; struct attribute_group *disk_attributes; struct request_queue *rq;
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