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Date: Sat, 31 Mar 2012 20:10:07 +0900
From: Joerg Sonnenberger <joerg@britannica.bec.de>
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Subject: Re: svn commit: r233700 - head/sys/kern
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On Fri, Mar 30, 2012 at 09:49:51PM +0200, 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;

I would really just move the ha = into the loop body -- same semantic
and no such issue as a dangling ;.

Joerg