linux-kernel - Re: [PATCH] mptsas: remove pointless null check

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Message-ID: <20081013153701.61f22485@lxorguk.ukuu.org.uk>
Date:	Mon, 13 Oct 2008 15:37:01 +0100
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	James Bottomley <James.Bottomley@...senPartnership.com>
Cc:	Jeff Garzik <jgarzik@...ox.com>, linux-ide@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-scsi <linux-scsi@...r.kernel.org>
Subject: Re: [PATCH] mptsas: remove pointless null check

> If I remember rightly this check is necessary because phy_info can be
> NULL in certain situations.  Your patch will trip this to oops.  What

In which case it will already have crashed

> your description needs to say is that we no longer need to check this
> pointer for NULL because it was checked somewhere else in the stack ...
> but I can't see where that is, where is it?

We don't check: but if it was NULL we then fall straight through and
dereference it unconditionally... so either its a wrong NULL check and
the old code oopses (which a trawl says it doesn't) or the check is bogus.

Alan
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