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Date: Wed, 30 Jul 2008 19:51:38 +0200 From: Karsten Keil <kkeil@...e.de> To: David Woodhouse <dwmw2@...radead.org> Cc: isdn4linux@...tserv.isdn4linux.de, Marcel Holtmann <marcel@...tmann.org>, Linus Torvalds <torvalds@...ux-foundation.org>, linux-kernel@...r.kernel.org Subject: Re: [PATCH] mISDN cleanup user interface On Wed, Jul 30, 2008 at 05:57:01PM +0100, David Woodhouse wrote: > On Wed, 2008-07-30 at 18:33 +0200, Karsten Keil wrote: > > What about this implementation ? > > Looks a lot saner... although it does seem to confirm my earlier > suspicion that you're not even _using_ the fact that it's a bitmap at > all. You set the bits for the present channels at init time, which are > always contiguous, and you never seem to change them them later -- why > couldn't you do this with a simple 'number of channels' integer? No it is not contineous on different PRI line setups (E1,T1 ...) e.g a E1 has the D-channel on channel 15 position, so this bit is not set then. My idea was, that with such a bitmap, applictions do not need to know anything about the different channel layouts, it can use the map as base to assign or validate a channel numbers. > > Are you later intending to use the bitmap to mark them as busy/free? > Yes exactely, and this was the reason why the original code (which used one u_long only as channelmap) already used the bit operators, since for a channel allocator you should be atomic, but since we are now allow 127 channels we need proper locking for the busy/free map anyways and so we do not need atomic operation here. -- Karsten Keil SuSE Labs ISDN and VOIP development SUSE LINUX Products GmbH, Maxfeldstr.5 90409 Nuernberg, GF: Markus Rex, HRB 16746 (AG Nuernberg) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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