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From: Johannes Berg <johannes@sipsolutions.net>
To: Michael Wu <flamingice@sourmilk.net>
Cc: John Linville <linville@tuxdriver.com>, linux-wireless@vger.kernel.org
Subject: Re: [PATCH 3/3] adm8211: Adapt to filter configuration API
Date: Thu, 20 Sep 2007 03:09:20 +0200	[thread overview]
Message-ID: <1190250560.18521.3.camel@johannes.berg> (raw)
In-Reply-To: <200709181742.33948.flamingice@sourmilk.net>

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On Tue, 2007-09-18 at 17:42 -0400, Michael Wu wrote:

> +	} else if ((*total_flags & FIF_ALLMULTI) || (mc_count > 32)) {

Why the > 32 btw? The other branch below:

> +	} else {
> +		priv->nar &= ~(ADM8211_NAR_MM | ADM8211_NAR_PR);
> +		mc_filter[1] = mc_filter[0] = 0;
> +		for (i = 0; i < mc_count; i++) {
> +			if (!mclist)
> +				break;
> +			bit_nr = ether_crc(ETH_ALEN, mclist->dmi_addr) >> 26;
> +
> +			bit_nr &= 0x3F;
> +			mc_filter[bit_nr >> 5] |= 1 << (bit_nr & 31);
> +			mclist = mclist->next;
> +		}

looks like it's a simple hashing algorithm to filter for the multicast
address, so any number of addresses should be ok as far as I can tell,
you just see all multicast frames in a given class of the 64 classes you
have. And if many of the >32 addresses hash to the same value, it might
still be advantageous to use the filter.

johannes

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      parent reply	other threads:[~2007-09-20 13:50 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20070918213833.8850.90828.stgit@magic.sourmilk.net>
2007-09-18 21:42 ` [PATCH 2/3] rtl8187: Adapt to filter configuration API Michael Wu
2007-09-18 21:42 ` [PATCH 3/3] adm8211: " Michael Wu
2007-09-19 17:46   ` Michael Buesch
2007-09-19 21:03     ` Michael Wu
2007-09-20 13:02       ` Michael Buesch
2007-09-20  1:09   ` Johannes Berg [this message]

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