linux-kernel - Re: [PATCH -next] nfs: fix ISO C90 warning

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Date:	Thu, 17 Dec 2009 18:00:29 +0800
From:	Américo Wang <xiyou.wangcong@...il.com>
To:	Trond Myklebust <trond.myklebust@....uio.no>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Randy Dunlap <randy.dunlap@...cle.com>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	linux-next@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	linux-nfs@...r.kernel.org
Subject: Re: [PATCH -next] nfs: fix ISO C90 warning

On Thu, Dec 17, 2009 at 7:01 AM, Trond Myklebust
<trond.myklebust@....uio.no> wrote:
> On Wed, 2009-12-16 at 23:58 +0100, Thomas Gleixner wrote:
>> On Wed, 16 Dec 2009, Randy Dunlap wrote:
>> > On Wed, 16 Dec 2009 17:40:19 -0500 Trond Myklebust wrote:
>> >
>> > > On Wed, 2009-12-16 at 14:23 -0800, Randy Dunlap wrote:
>> > > > From: Randy Dunlap <randy.dunlap@...cle.com>
>> > > >
>> > > > Fix gcc ISO C90 warning:
>> > > >
>> > > > fs/nfs/callback.c:356: warning: ISO C90 forbids mixed declarations and code
>> > > >
>> > > > Signed-off-by: Randy Dunlap <randy.dunlap@...cle.com>
>> > > > ---
>> > > >  fs/nfs/callback.c |    2 +-
>> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
>> > > >
>> > > > --- linux-next-20091215.orig/fs/nfs/callback.c
>> > > > +++ linux-next-20091215/fs/nfs/callback.c
>> > > > @@ -352,8 +352,8 @@ static int check_gss_callback_principal(
>> > > >  static int nfs_callback_authenticate(struct svc_rqst *rqstp)
>> > > >  {
>> > > >         struct nfs_client *clp;
>> > > > -       RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
>> > > >         int ret = SVC_OK;
>> > > > +       RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
>> > > >
>> > >
>> > > What version of gcc is giving rise to this warning?
>> >
>> > > gcc --version
>> > gcc (GCC) 4.2.1 (SUSE Linux)
>> >
>> > > RPC_IFDEBUG is a macro that either evaluates to its argument, or to
>> > > nothing, depending on whether or not RPC_DEBUG is defined or not. In
>> > > neither case should it evaluate to anything illegal under C90 rules
>> > > afaics.
>> >
>> > Yep.  Odd warning.
>>
>> Not really. If the debug macro evaluates to nothing then you have:
>>
>>     struct nfs_client *clp;
>>     ;
>>     int ret = SVC_OK;
>>
>> So you have a stray semicolon, which is interpreted as an empty code
>> line. That qualifies for the mixed declaration and code case :)
>>
>> I know it's nitpicking, but ...
>
> Ah... I see what you mean.
>
> So really what we should do is just move that semicolon inside the
> macro. That would change the !RPC_DEBUG case to
>
>    struct nfs_client *clp;
>
>    int ret = SVC_OK;
>
> which is 100% legal...
>

Hi,
Check that currently all usages of RPC_DEBUG are the same,
we can replace them all.

What do you think about the attached patch?

Sorry for attaching it, I have a bad mail environment here.

Signed-off-by: WANG Cong <xiyou.wangcong@...il.com>

View attachment "rpc-replace-rpc-ifdebug.diff" of type "text/plain" (3004 bytes)