linux-kernel - Re: [PATCH] befs/btree: remove unneeded initializations

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Date:	Wed, 1 Jun 2016 15:42:40 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Luis de Bethencourt <luisbg@....samsung.com>
Cc:	linux-kernel@...r.kernel.org, viro@...iv.linux.org.uk,
	fabf@...net.be
Subject: Re: [PATCH] befs/btree: remove unneeded initializations

On Mon, 30 May 2016 01:39:59 +0100 Luis de Bethencourt <luisbg@....samsung.com> wrote:

> off in befs_bt_read_node() will be written by befs_read_datastream(), with
> the value that node->od_node needs.
> 
> node_off in befs_btree_read() isn't read before set to root_node_ptr.
> 
> Removing these two unneeded initializations.
>
> ...
>
> --- a/fs/befs/btree.c
> +++ b/fs/befs/btree.c
> @@ -196,7 +196,7 @@ static int
>  befs_bt_read_node(struct super_block *sb, const befs_data_stream *ds,
>  		  struct befs_btree_node *node, befs_off_t node_off)
>  {
> -	uint off = 0;
> +	uint off;
>  
>  	befs_debug(sb, "---> %s", __func__);
>  

With this code:

	int foo;

	bar(&foo);

	whatever = foo;

some versions of gcc will warn that foo might be used uninitialized. 
Other versions of gcc don't do this.  That's why the seemingly-unneeded
initializations are there.

Neither of the versions of gcc which I tested with actually do warn,
but I'm inclined to leave things as-is: some people will get warnings
and that's probably worse than a couple of bytes bloat in befs.

It shouldn't cause any bloat, really.  We have the "uninitialized_var"
macro which avoids any bloat and is self-documenting.  And the nice
thing about self-documenting code is that it prevents Andrew from
having to explain strange code to Luis ;)  But unintialized_var in
unpopular for reasons which I personally find unpersuasive, given
the advantages...