5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> [ Upstream commit 00358933f66c44d511368a57eb421e172447cfb9 ] 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@xxxxxxxxxxxxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> Reviewed-by: Luis Chamberlain <mcgrof@xxxxxxxxxx> Link: https://lore.kernel.org/r/6b074af7-c165-4fab-b7da-8270a4f6f6cd@xxxxxxxxxxxxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Stable-dep-of: 826cc42adf44 ("brd: defer automatic disk creation until module initialization succeeds") Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/block/brd.c | 73 +++++++++++++++++++-------------------------- 1 file changed, 30 insertions(+), 43 deletions(-) diff --git a/drivers/block/brd.c b/drivers/block/brd.c index 76ce6f766d55e..db816baca5567 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); @@ -431,9 +423,7 @@ 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; } @@ -443,15 +433,19 @@ 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) @@ -475,9 +469,18 @@ 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. @@ -493,28 +496,16 @@ 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; @@ -522,13 +513,9 @@ static int __init brd_init(void) 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"); } -- 2.43.0
