linux-kernel - Re: [PATCH net-next] ether_addr_equal: Optimize implementation, remove unused compare_ether

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Message-ID: <20131205153229.187f7604@nehalam.linuxnetplumber.net>
Date:	Thu, 5 Dec 2013 15:32:29 -0800
From:	Stephen Hemminger <stephen@...workplumber.org>
To:	Joe Perches <joe@...ches.com>
Cc:	netdev@...r.kernel.org, Rob Landley <rob@...dley.net>,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] ether_addr_equal: Optimize implementation,
 remove unused compare_ether_addr

On Thu,  5 Dec 2013 14:54:38 -0800
Joe Perches <joe@...ches.com> wrote:

> +#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
> +	u32 fold = ((*(const u32 *)addr1) ^ (*(const u32 *)addr2)) |
> +		   ((*(const u16 *)(addr1 + 4)) ^ (*(const u16 *)(addr2 + 4)));
> +
> +	return fold == 0;

Why the temporary variable. You can just do:
	return ((*(const u32 *)addr1) ^ (*(const u32 *)addr2)) |
	       ((*(const u16 *)(addr1 + 4)) ^ (*(const u16 *)(addr2 + 4))) != 0;

Or
	return !!((*(const u32 *)addr1) ^ (*(const u32 *)addr2)) |
	         ((*(const u16 *)(addr1 + 4)) ^ (*(const u16 *)(addr2 + 4))));
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