Re: [PATCH -next 1/3] nbd: fold nbd config initialization into nbd_alloc_config()

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在 2023/07/07 11:15, Zhong Jinghua 写道:
From: Zhong Jinghua <zhongjinghua@xxxxxxxxxx>

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


LGTM
Reviewed-by: Yu Kuai <yukuai3@xxxxxxxxxx>

Signed-off-by: Zhong Jinghua <zhongjinghua@xxxxxxxxxx>
---
  drivers/block/nbd.c | 41 +++++++++++++++++++----------------------
  1 file changed, 19 insertions(+), 22 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index cb38477f359f..cd6d78914954 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1526,17 +1526,20 @@ static int nbd_ioctl(struct block_device *bdev, fmode_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);
@@ -1544,7 +1547,10 @@ 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 block_device *bdev, fmode_t mode)
@@ -1563,21 +1569,17 @@ static int nbd_open(struct block_device *bdev, fmode_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)
@@ -1979,22 +1981,17 @@ static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info)
  		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;





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