From f7bf35862477d6d4f8a9746c645a4380de984700 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Tue, 7 Sep 2021 19:18:00 +0900 Subject: [PATCH] brd: reduce the brd_devices_mutex scope As with commit 8b52d8be86d72308 ("loop: reorder loop_exit"), unregister_blkdev() needs to be called first in order to avoid calling brd_alloc() from brd_probe() after brd_del_one() from brd_exit(). Then, we can avoid holding global mutex during add_disk()/del_gendisk() as with commit 1c500ad706383f1a ("loop: reduce the loop_ctl_mutex scope"). Signed-off-by: Tetsuo Handa Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/e205f13d-18ff-a49c-0988-7de6ea5ff823@i-love.sakura.ne.jp Signed-off-by: Jens Axboe --- drivers/block/brd.c | 44 ++++++++++++++++++++++---------------------- 1 file changed, 22 insertions(+), 22 deletions(-) diff --git a/drivers/block/brd.c b/drivers/block/brd.c index 58ec167..530b312 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -373,10 +373,22 @@ static int brd_alloc(int i) struct gendisk *disk; char buf[DISK_NAME_LEN]; + mutex_lock(&brd_devices_mutex); + list_for_each_entry(brd, &brd_devices, brd_list) { + if (brd->brd_number == i) { + mutex_unlock(&brd_devices_mutex); + return -EEXIST; + } + } brd = kzalloc(sizeof(*brd), GFP_KERNEL); - if (!brd) + if (!brd) { + mutex_unlock(&brd_devices_mutex); 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); @@ -411,37 +423,30 @@ static int brd_alloc(int i) blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue); blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, disk->queue); add_disk(disk); - list_add_tail(&brd->brd_list, &brd_devices); return 0; out_free_dev: + mutex_lock(&brd_devices_mutex); + list_del(&brd->brd_list); + mutex_unlock(&brd_devices_mutex); kfree(brd); return -ENOMEM; } static void brd_probe(dev_t dev) { - int i = MINOR(dev) / max_part; - struct brd_device *brd; - - mutex_lock(&brd_devices_mutex); - list_for_each_entry(brd, &brd_devices, brd_list) { - if (brd->brd_number == i) - goto out_unlock; - } - - brd_alloc(i); -out_unlock: - mutex_unlock(&brd_devices_mutex); + brd_alloc(MINOR(dev) / max_part); } static void brd_del_one(struct brd_device *brd) { - list_del(&brd->brd_list); 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); } @@ -491,25 +496,21 @@ static int __init brd_init(void) brd_debugfs_dir = debugfs_create_dir("ramdisk_pages", NULL); - mutex_lock(&brd_devices_mutex); for (i = 0; i < rd_nr; i++) { err = brd_alloc(i); if (err) goto out_free; } - mutex_unlock(&brd_devices_mutex); - 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); - mutex_unlock(&brd_devices_mutex); - unregister_blkdev(RAMDISK_MAJOR, "ramdisk"); pr_info("brd: module NOT loaded !!!\n"); return err; @@ -519,13 +520,12 @@ 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); - unregister_blkdev(RAMDISK_MAJOR, "ramdisk"); - pr_info("brd: module unloaded\n"); } -- 2.7.4