Date: Fri, 17 Sep 2004 15:05:32 +0200
From: Stelian Pop <stelian@popies.net>
To: Duncan Sands <baldrick@free.fr>
Cc: Hugh Dickins <hugh@veritas.com>, Andrew Morton <akpm@osdl.org>,
       linux-kernel@vger.kernel.org
Subject: Re: [RFC, 2.6] a simple FIFO implementation
Message-ID: <20040917130532.GA22386@sd291.sivit.org>
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On Fri, Sep 17, 2004 at 03:00:35PM +0200, Duncan Sands wrote:

> > But the order in which in and out get modified guarantees that you
> > will still have a coherent content (provided the assignments are 
> > atomic, which they are).
> 
> Hi Stelian, what is to stop the compiler putting, say, "in" in a register
> for the process calling __kfifo_get, so that it only sees a constant
> value.  Then after a while that process will think there is nothing
> to get even though another process is shoving stuff into the fifo and
> modifying "in".

This can happen all right, but the buffer (or the indices) will not
get corrupt (this is what I call coherent). Its just like the __kfifo_get()
was executed entirely before the __kfifo_put().

There is no problem here.

> 
> By the way, the comment for __kfifo_get has a typo:
> 
> + * kfifo_get - gets some data from the FIFO, no locking version
>     ^^^^^^^^^ should be __kfifo_get

Same for kfifo_len, too much cut & paste here. Thanks.

Stelian.
-- 
Stelian Pop <stelian@popies.net>    
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