netdev - Re: [KJ] [PATCH] net/core/flow.c: compare data with memcmp

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Date:	Sun, 31 Dec 2006 11:49:39 -0800
From:	Nishanth Aravamudan <nacc@...ibm.com>
To:	Daniel Marjamäki <daniel.marjamaki@...il.com>
Cc:	netdev@...r.kernel.org, kernel-janitors@...ts.osdl.org,
	linux-kernel@...r.kernel.org
Subject: Re: [KJ] [PATCH] net/core/flow.c: compare data with memcmp

On 31.12.2006 [17:37:05 +0100], Daniel Marjam?ki wrote:
> From: Daniel Marjamäki
> This has been tested by me.
> Signed-off-by: Daniel Marjamäki <daniel.marjamaki@...il.com>
> --- linux-2.6.20-rc2/net/core/flow.c	2006-12-27 09:59:56.000000000 +0100
> +++ linux/net/core/flow.c	2006-12-31 18:26:06.000000000 +0100
> @@ -144,29 +144,16 @@ typedef u32 flow_compare_t;
> 
>  extern void flowi_is_missized(void);
> 
> -/* I hear what you're saying, use memcmp.  But memcmp cannot make
> - * important assumptions that we can here, such as alignment and
> - * constant size.
> - */
>  static int flow_key_compare(struct flowi *key1, struct flowi *key2)
>  {
> -	flow_compare_t *k1, *k1_lim, *k2;
> -	const int n_elem = sizeof(struct flowi) / sizeof(flow_compare_t);
> -
>  	if (sizeof(struct flowi) % sizeof(flow_compare_t))
>  		flowi_is_missized();
> 
> -	k1 = (flow_compare_t *) key1;
> -	k1_lim = k1 + n_elem;
> -
> -	k2 = (flow_compare_t *) key2;
> -
> -	do {
> -		if (*k1++ != *k2++)
> -			return 1;
> -	} while (k1 < k1_lim);
> +	/* Number of elements to compare */
> +	const int n_elem = sizeof(struct flowi) / sizeof(flow_compare_t);
> 
> -	return 0;
> +	/* Compare all elements in key1 and key2. */
> +	return memcmp(key1, key2, n_elem * sizeof(flow_compare_t));
>  }

Small nit, I don't think either of your comments make the code any
clearer than the code on its own, so drop them both.

Thanks,
Nish

-- 
Nishanth Aravamudan <nacc@...ibm.com>
IBM Linux Technology Center
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