linux-kernel - Re: [PATCH] btrfs: fix uninitialized variable warning

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Date:   Fri, 24 Mar 2023 10:24:55 +0800
From:   Qu Wenruo <quwenruo.btrfs@....com>
To:     Genjian <zhanggenjian123@...il.com>, clm@...com,
        josef@...icpanda.com, dsterba@...e.com
Cc:     linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        Genjian Zhang <zhanggenjian@...inos.cn>,
        k2ci <kernel-bot@...inos.cn>
Subject: Re: [PATCH] btrfs: fix uninitialized variable warning



On 2023/3/24 10:08, Genjian wrote:
> From: Genjian Zhang <zhanggenjian@...inos.cn>
> 
> compiler warning:

Compiler version please.

> 
> ../fs/btrfs/volumes.c: In function ‘btrfs_init_new_device’:
> ../fs/btrfs/volumes.c:2703:3: error: ‘seed_devices’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>   2703 |   btrfs_setup_sprout(fs_info, seed_devices);
>        |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> ../fs/btrfs/send.c: In function ‘get_cur_inode_state’:
> ../include/linux/compiler.h:70:32: error: ‘right_gen’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>     70 |   (__if_trace.miss_hit[1]++,1) :  \
>        |                                ^
> ../fs/btrfs/send.c:1878:6: note: ‘right_gen’ was declared here
>   1878 |  u64 right_gen;
>        |      ^~~~~~~~~
> 
> Initialize the uninitialized variables.
> 
> Reported-by: k2ci <kernel-bot@...inos.cn>
> Signed-off-by: Genjian Zhang <zhanggenjian@...inos.cn>
> ---
>   fs/btrfs/send.c    | 2 +-
>   fs/btrfs/volumes.c | 2 +-
>   2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
> index e5c963bb873d..af2e153543a5 100644
> --- a/fs/btrfs/send.c
> +++ b/fs/btrfs/send.c
> @@ -1875,7 +1875,7 @@ static int get_cur_inode_state(struct send_ctx *sctx, u64 ino, u64 gen,
>   	int left_ret;
>   	int right_ret;
>   	u64 left_gen;
> -	u64 right_gen;
> +	u64 right_gen = 0;

IIRC this is not my first time explaining why this is a false alert.

Thus please report your compiler version first.

Thanks,
Qu
>   	struct btrfs_inode_info info;
>   
>   	ret = get_inode_info(sctx->send_root, ino, &info);
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 7823168c08a6..7163c98e47be 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -2609,7 +2609,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
>   	struct block_device *bdev;
>   	struct super_block *sb = fs_info->sb;
>   	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
> -	struct btrfs_fs_devices *seed_devices;
> +	struct btrfs_fs_devices *seed_devices = NULL;
>   	u64 orig_super_total_bytes;
>   	u64 orig_super_num_devices;
>   	int ret = 0;