linux-kernel - Re: isdn/eicon: msg_in_{wrap,read}

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Message-ID: <alpine.DEB.0.99.0807281640290.16833@k10.melware.de>
Date:	Mon, 28 Jul 2008 16:41:18 +0200 (CEST)
From:	Armin Schindler <armin@...ware.de>
To:	roel kluin <roel.kluin@...il.com>
cc:	linux-kernel@...r.kernel.org
Subject: Re: isdn/eicon: msg_in_{wrap,read}_pos assigned twice?

On Fri, 25 Jul 2008, roel kluin wrote:
> vi drivers/isdn/hardware/eicon/message.c +4035
>
> and note two similar tests on line 4035 and 4049:
>
> [else] if (plci->msg_in_read_pos == plci->msg_in_wrap_pos)
>
> after the first test:
>
> 	plci->msg_in_wrap_pos = MSG_IN_QUEUE_SIZE;
> 	plci->msg_in_read_pos = i + MSG_IN_OVERHEAD;
>
> but then after the second test as well:
>
> 	plci->msg_in_read_pos = MSG_IN_QUEUE_SIZE;
> 	plci->msg_in_wrap_pos = MSG_IN_QUEUE_SIZE;
>
>
> So the assignment after the first test has no effect. Is this a bug?

If (plci->msg_in_read_pos == plci->msg_in_wrap_pos) is true in the first 
test it can't be true in the second.
So the code could be optimized a bit. But the first assignments are needed.

If it's false in the first it may become true in the second. So it's not a 
bug. All conditions are really needed.

Armin

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