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From: John Baldwin <jhb@freebsd.org>
To: Dimitry Andric <dim@freebsd.org>
Date: Mon, 2 Apr 2012 07:52:52 -0400
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	(bigwig.baldwin.cx); Mon, 02 Apr 2012 10:31:45 -0400 (EDT)
Cc: src-committers@freebsd.org, svn-src-all@freebsd.org,
	Scott Long <scottl@freebsd.org>, Stefan Farfeleder <stefanf@freebsd.org>,
	David Xu <davidxu@freebsd.org>, svn-src-head@freebsd.org
Subject: Re: svn commit: r233700 - head/sys/kern
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On Friday, March 30, 2012 3:49:51 pm Dimitry Andric wrote:
> On 2012-03-30 15:30, Stefan Farfeleder wrote:
> > here are a few similar cases.
> 
> Hm, what about this one that clang warns about:
> 
>    sys/dev/asr/asr.c:2420:57: warning: for loop has empty body [-Wempty-
body]
> 	  for (ha = &Asr_softc_list; *ha; ha = &((*ha)->ha_next));
> 								 ^
>    sys/dev/asr/asr.c:2420:57: note: put the semicolon on a separate line to 
silence this warning [-Wempty-body]
> 
> I'm not sure about it though, the code looks like this:
> 
> static int
> asr_attach(device_t dev)
> {
> [...]
>          Asr_softc_t              *sc, **ha;
> [...]
>          LIST_INIT(&(sc->ha_ccb));
>          /* Link us into the HA list */
>          for (ha = &Asr_softc_list; *ha; ha = &((*ha)->ha_next));
>                  *(ha) = sc;
> 
> It seems the for loop walks the list until the end, then tacks 'sc' onto
> it.
> 
> So to 'fix' the warning, and make the meaning more explicit, we should
> probably rewrite that fragment as:
> 
>          LIST_INIT(&(sc->ha_ccb));
>          /* Link us into the HA list */
>          for (ha = &Asr_softc_list; *ha; ha = &((*ha)->ha_next))
> 		;
> 	*(ha) = sc;
> 
> Is this OK?

Can we just make that code use a STAILQ() instead of doing it obscurely by 
hand?

-- 
John Baldwin