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author | Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> | 2022-01-06 18:53:16 +0900 |
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committer | Jens Axboe <axboe@kernel.dk> | 2022-01-17 07:19:40 -0700 |
commit | 00358933f66c44d511368a57eb421e172447cfb9 (patch) | |
tree | d2eb3e96ccf410dd73ddb8c23329960367d683e6 /drivers/block | |
parent | a6431e351c6ec5bb6800787d259b343088f369a3 (diff) | |
download | linux-stable-00358933f66c44d511368a57eb421e172447cfb9.tar.gz linux-stable-00358933f66c44d511368a57eb421e172447cfb9.tar.bz2 linux-stable-00358933f66c44d511368a57eb421e172447cfb9.zip |
brd: remove brd_devices_mutex mutex
If brd_alloc() from brd_probe() is called before brd_alloc() from
brd_init() is called, module loading will fail with -EEXIST error.
To close this race, call __register_blkdev() just before leaving
brd_init().
Then, we can remove brd_devices_mutex mutex, for brd_device list
will no longer be accessed concurrently.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/6b074af7-c165-4fab-b7da-8270a4f6f6cd@i-love.sakura.ne.jp
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/block')
-rw-r--r-- | drivers/block/brd.c | 73 |
1 files changed, 30 insertions, 43 deletions
diff --git a/drivers/block/brd.c b/drivers/block/brd.c index 8fe2e4289dae..6e3f2f0d2352 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -362,7 +362,6 @@ __setup("ramdisk_size=", ramdisk_size); * (should share code eventually). */ static LIST_HEAD(brd_devices); -static DEFINE_MUTEX(brd_devices_mutex); static struct dentry *brd_debugfs_dir; static int brd_alloc(int i) @@ -372,21 +371,14 @@ static int brd_alloc(int i) char buf[DISK_NAME_LEN]; int err = -ENOMEM; - mutex_lock(&brd_devices_mutex); - list_for_each_entry(brd, &brd_devices, brd_list) { - if (brd->brd_number == i) { - mutex_unlock(&brd_devices_mutex); + list_for_each_entry(brd, &brd_devices, brd_list) + if (brd->brd_number == i) return -EEXIST; - } - } brd = kzalloc(sizeof(*brd), GFP_KERNEL); - if (!brd) { - mutex_unlock(&brd_devices_mutex); + if (!brd) return -ENOMEM; - } brd->brd_number = i; list_add_tail(&brd->brd_list, &brd_devices); - mutex_unlock(&brd_devices_mutex); spin_lock_init(&brd->brd_lock); INIT_RADIX_TREE(&brd->brd_pages, GFP_ATOMIC); @@ -429,9 +421,7 @@ static int brd_alloc(int i) out_cleanup_disk: blk_cleanup_disk(disk); out_free_dev: - mutex_lock(&brd_devices_mutex); list_del(&brd->brd_list); - mutex_unlock(&brd_devices_mutex); kfree(brd); return err; } @@ -441,15 +431,19 @@ static void brd_probe(dev_t dev) brd_alloc(MINOR(dev) / max_part); } -static void brd_del_one(struct brd_device *brd) +static void brd_cleanup(void) { - del_gendisk(brd->brd_disk); - blk_cleanup_disk(brd->brd_disk); - brd_free_pages(brd); - mutex_lock(&brd_devices_mutex); - list_del(&brd->brd_list); - mutex_unlock(&brd_devices_mutex); - kfree(brd); + struct brd_device *brd, *next; + + debugfs_remove_recursive(brd_debugfs_dir); + + list_for_each_entry_safe(brd, next, &brd_devices, brd_list) { + del_gendisk(brd->brd_disk); + blk_cleanup_disk(brd->brd_disk); + brd_free_pages(brd); + list_del(&brd->brd_list); + kfree(brd); + } } static inline void brd_check_and_reset_par(void) @@ -473,9 +467,18 @@ static inline void brd_check_and_reset_par(void) static int __init brd_init(void) { - struct brd_device *brd, *next; int err, i; + brd_check_and_reset_par(); + + brd_debugfs_dir = debugfs_create_dir("ramdisk_pages", NULL); + + for (i = 0; i < rd_nr; i++) { + err = brd_alloc(i); + if (err) + goto out_free; + } + /* * brd module now has a feature to instantiate underlying device * structure on-demand, provided that there is an access dev node. @@ -491,28 +494,16 @@ static int __init brd_init(void) * dynamically. */ - if (__register_blkdev(RAMDISK_MAJOR, "ramdisk", brd_probe)) - return -EIO; - - brd_check_and_reset_par(); - - brd_debugfs_dir = debugfs_create_dir("ramdisk_pages", NULL); - - for (i = 0; i < rd_nr; i++) { - err = brd_alloc(i); - if (err) - goto out_free; + if (__register_blkdev(RAMDISK_MAJOR, "ramdisk", brd_probe)) { + err = -EIO; + goto out_free; } pr_info("brd: module loaded\n"); return 0; out_free: - unregister_blkdev(RAMDISK_MAJOR, "ramdisk"); - debugfs_remove_recursive(brd_debugfs_dir); - - list_for_each_entry_safe(brd, next, &brd_devices, brd_list) - brd_del_one(brd); + brd_cleanup(); pr_info("brd: module NOT loaded !!!\n"); return err; @@ -520,13 +511,9 @@ out_free: static void __exit brd_exit(void) { - struct brd_device *brd, *next; unregister_blkdev(RAMDISK_MAJOR, "ramdisk"); - debugfs_remove_recursive(brd_debugfs_dir); - - list_for_each_entry_safe(brd, next, &brd_devices, brd_list) - brd_del_one(brd); + brd_cleanup(); pr_info("brd: module unloaded\n"); } |