linux-kernel - Re: [PATCH] fs: wipe off the compiler warn

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Message-Id: <20160729160247.564e27525f04416ef714ddd4@linux-foundation.org>
Date:	Fri, 29 Jul 2016 16:02:47 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	zhongjiang <zhongjiang@...wei.com>
Cc:	<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fs: wipe off the compiler warn

On Fri, 29 Jul 2016 22:46:39 +0800 zhongjiang <zhongjiang@...wei.com> wrote:

> From: zhong jiang <zhongjiang@...wei.com>
> 
> when compile the kenrel code, I happens to the following warn.
> fs/reiserfs/ibalance.c:1156:2: warning: ___new_insert_key___ may be used
> uninitialized in this function.
> memcpy(new_insert_key_addr, &new_insert_key, KEY_SIZE);
> ^
> The patch just fix it to avoid the warn.
> 
> Signed-off-by: zhong jiang <zhongjiang@...wei.com>
> ---
>  fs/reiserfs/ibalance.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/reiserfs/ibalance.c b/fs/reiserfs/ibalance.c
> index b751eea..512ce95 100644
> --- a/fs/reiserfs/ibalance.c
> +++ b/fs/reiserfs/ibalance.c
> @@ -818,7 +818,7 @@ int balance_internal(struct tree_balance *tb,
>  	int order;
>  	int insert_num, n, k;
>  	struct buffer_head *S_new;
> -	struct item_head new_insert_key;
> +	struct item_head uninitialized_var(new_insert_key);
>  	struct buffer_head *new_insert_ptr = NULL;
>  	struct item_head *new_insert_key_addr = insert_key;

How do we know this isn't a real bug?  It isn't obvious to me that this
warning is a false positive.