nbd: fold nbd config initialization into nbd_alloc_config()

[ Upstream commit 1b59860540a4018e8071dc18d4893ec389506b7d ]

There are no functional changes, make the code cleaner and prepare to
fix null-ptr-dereference while accessing 'nbd->config'.

Signed-off-by: Li Nan <linan122@huawei.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/r/20231116162316.1740402-2-linan666@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 855fdf5..02f8448 100644 (file)
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1530,17 +1530,20 @@ static int nbd_ioctl(struct block_device *bdev, blk_mode_t mode,
        return error;
 }
 
-static struct nbd_config *nbd_alloc_config(void)
+static int nbd_alloc_and_init_config(struct nbd_device *nbd)
 {
        struct nbd_config *config;
 
+       if (WARN_ON(nbd->config))
+               return -EINVAL;
+
        if (!try_module_get(THIS_MODULE))
-               return ERR_PTR(-ENODEV);
+               return -ENODEV;
 
        config = kzalloc(sizeof(struct nbd_config), GFP_NOFS);
        if (!config) {
                module_put(THIS_MODULE);
-               return ERR_PTR(-ENOMEM);
+               return -ENOMEM;
        }
 
        atomic_set(&config->recv_threads, 0);
@@ -1548,7 +1551,10 @@ static struct nbd_config *nbd_alloc_config(void)
        init_waitqueue_head(&config->conn_wait);
        config->blksize_bits = NBD_DEF_BLKSIZE_BITS;
        atomic_set(&config->live_connections, 0);
-       return config;
+       nbd->config = config;
+       refcount_set(&nbd->config_refs, 1);
+
+       return 0;
 }
 
 static int nbd_open(struct gendisk *disk, blk_mode_t mode)
@@ -1567,21 +1573,17 @@ static int nbd_open(struct gendisk *disk, blk_mode_t mode)
                goto out;
        }
        if (!refcount_inc_not_zero(&nbd->config_refs)) {
-               struct nbd_config *config;
-
                mutex_lock(&nbd->config_lock);
                if (refcount_inc_not_zero(&nbd->config_refs)) {
                        mutex_unlock(&nbd->config_lock);
                        goto out;
                }
-               config = nbd_alloc_config();
-               if (IS_ERR(config)) {
-                       ret = PTR_ERR(config);
+               ret = nbd_alloc_and_init_config(nbd);
+               if (ret) {
                        mutex_unlock(&nbd->config_lock);
                        goto out;
                }
-               nbd->config = config;
-               refcount_set(&nbd->config_refs, 1);
+
                refcount_inc(&nbd->refs);
                mutex_unlock(&nbd->config_lock);
                if (max_part)
@@ -1990,22 +1992,17 @@ again:
                pr_err("nbd%d already in use\n", index);
                return -EBUSY;
        }
-       if (WARN_ON(nbd->config)) {
-               mutex_unlock(&nbd->config_lock);
-               nbd_put(nbd);
-               return -EINVAL;
-       }
-       config = nbd_alloc_config();
-       if (IS_ERR(config)) {
+
+       ret = nbd_alloc_and_init_config(nbd);
+       if (ret) {
                mutex_unlock(&nbd->config_lock);
                nbd_put(nbd);
                pr_err("couldn't allocate config\n");
-               return PTR_ERR(config);
+               return ret;
        }
-       nbd->config = config;
-       refcount_set(&nbd->config_refs, 1);
-       set_bit(NBD_RT_BOUND, &config->runtime_flags);
 
+       config = nbd->config;
+       set_bit(NBD_RT_BOUND, &config->runtime_flags);
        ret = nbd_genl_size_set(info, nbd);
        if (ret)
                goto out;