linux-kernel - Re: new sparse warning fs/cifs/cifsfs.c:168:15: warning: dereference of noderef expression fs/cifs/cifsfs.c:542:15: warning: dereference of noderef expression

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Message-ID: <CAH2r5mvxRfrAUA9kXwCojg_0_YTC=W623A-tqERBkeWL5pvf6g@mail.gmail.com>
Date:	Sun, 7 Aug 2011 14:32:26 -0500
From:	Steve French <smfrench@...il.com>
To:	Al Viro <viro@...iv.linux.org.uk>
Cc:	LKML <linux-kernel@...r.kernel.org>, linux-cifs@...r.kernel.org
Subject: Re: new sparse warning fs/cifs/cifsfs.c:168:15: warning: dereference
 of noderef expression fs/cifs/cifsfs.c:542:15: warning: dereference of
 noderef expression

On Sun, Aug 7, 2011 at 12:48 PM, Al Viro <viro@...iv.linux.org.uk> wrote:
> On Sun, Aug 07, 2011 at 11:22:51AM -0500, Steve French wrote:
>> I noticed a series of sparse warnings (on all calls to cifs's GetXid
>> after building on a newly install fc15 system (yum installed a sparse
>> binary dated June 23).
>>
>> fs/cifs/cifsfs.c:168:15: warning: dereference of noderef expression
>> fs/cifs/cifsfs.c:542:15: warning: dereference of noderef expression
>>
>> Has sparse changed to add a new warning - I see (from quick search)
>> others getting this on other modules years ago, but I didn't see
>> anything obvious wrong with the definition of the function, and I
>> hadn't noticed sparse complaining about it before, and would like to
>> remove the 50+ new messages as they clutter the build output.
>
> It's not sparse change - the whinge comes from current_fsuid(), i.e. direct
> read of current->cred, even though it's declared with __rcu.  The thing is,
> current->cred does *not* need rcu_dereference() - only the task itself
> can change it.  Easily fixed...

your change makes sense - thx


Steve
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