Subject: Re: [PATCH] [0/6] kfifo fixes/improvements
From: Andy Walls <awalls@radix.net>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Stefani Seibold <stefani@seibold.net>, Andi Kleen <andi@firstfloor.org>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
       "akpm@osdl.org" <akpm@osdl.org>
In-Reply-To: <64D5262E-28CF-41E8-9425-F8C5DD0A2265@gmail.com>
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Date: Wed, 30 Dec 2009 12:15:42 -0500
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On Tue, 2009-12-29 at 14:27 -0800, Dmitry Torokhov wrote:
> On Dec 29, 2009, at 12:40 AM, Stefani Seibold <stefani@seibold.net>  
> wrote:
> 
> > Am Montag, den 28.12.2009, 21:40 +0100 schrieb Andi Kleen:
> >
> >
> >> OK i checked and they all use power-of-two currently so by sheer
> >> luck (I doubt it is by design) they work. Still I think that
> >> open deathtrap should be fixed.
> >>
> >
> > It is fixed, and i hope it will be included in 2.6.34.
> >
> >> I also don't understand how that patch "breaks your future work"
> >> Please elaborate on that.
> >>
> >
> > Very difficult to explain in a email, but i will try it:
> >
> > The new macro based kfifo API handles everything as elements of a  
> > given
> > type. So you can have the old "unsigned char"-fifo, but also fifo of
> > every other type like int's, struct's and so on. The kfifo_in() and
> > kfifo_out() len parameter is than in the meaning of elements not  
> > bytes.
> > So you are able to process more than one value at a time and the  
> > macros
> > will return the number of processed elements (not bytes).
> 
> Does anyone want this kind of functionality though? Why can't we keep  
> the old interface as is (and maybe deprecate it) and use the new  
> record API you mentioned below for record-oriented kfifos.

Yes.  I will eventually convert my use of kfifo to use records of size
'u32' as opposed to reading and writing in multiples of 4 bytes.  (I
have some ugly checks right now to make sure whenever I read from a
kfifo I get back a multiple of 4 bytes.)

I'm just waiting for the churn to settle.

Regards,
Andy

> Thanks.


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