linux-kernel - Re: [PATCH] mpt2sas: Fix &&/|| confusion in _scsih_sas_device_status_change

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Message-Id: <20100112135410.1506be72.akpm@linux-foundation.org>
Date:	Tue, 12 Jan 2010 13:54:10 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	roel kluin <roel.kluin@...il.com>
Cc:	"Moore, Eric" <Eric.Moore@....com>,
	"James E.J. Bottomley" <James.Bottomley@...e.de>,
	"linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"Desai, Kashyap" <Kashyap.Desai@....com>
Subject: Re: [PATCH] mpt2sas: Fix &&/|| confusion in
 _scsih_sas_device_status_change_event()

On Thu, 7 Jan 2010 20:58:10 +0100
roel kluin <roel.kluin@...il.com> wrote:

> On Thu, Jan 7, 2010 at 8:31 PM, Moore, Eric <Eric.Moore@....com> wrote:
> > nack
> >
> > The code beyond this check is intended for either INTERNAL_DEVICE_RESET or CMP_DEVICE_RESET. __ If the reason code is something else, we will want to return. __There are 10 other types of reason codes besides these two. This proposed patch means we return only when the reason code is either INTERNAL_DEVICE_RESET or CMP_INTERNAL_RESET.
> >
> > Eric Moore
> 
> my patch is correct but my changelog was wrong. Sorry for the
> confusion. It should have been:
> 
> Even if the ReasonCode is not INTERNAL_DEVICE_RESET nor CMP_DEVICE_RESET
> this still evaluates to true.
> 

yup, the current code is wrong.

	if (!(event_data->ReasonCode ==
	    MPI2_EVENT_SAS_DEV_STAT_RC_INTERNAL_DEVICE_RESET &&
	   event_data->ReasonCode ==
	    MPI2_EVENT_SAS_DEV_STAT_RC_CMP_INTERNAL_DEV_RESET))
		return;

ReasonCode cannot equal two different things at the same time.

This is what we want:

	if (event_data->ReasonCode !=
	      MPI2_EVENT_SAS_DEV_STAT_RC_INTERNAL_DEVICE_RESET &&
	    event_data->ReasonCode !=
	      MPI2_EVENT_SAS_DEV_STAT_RC_CMP_INTERNAL_DEV_RESET)
		return;

Eric, the fix needs runtime testing please - it enables code which
hasn't been executed in a long time, if ever.

In fact the compiler wasn't even emitting any code for the second half
of _scsih_sas_device_status_change_event() because it worked out that
there was no path to it.


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