Re: [PATCH] perf/x86/intel: Mark expected switch fall-throughs

Joe Perches
2019-06-24T19:46:01Z

On Mon, 2019-06-24 at 21:31 +0200, Peter Zijlstra wrote:
> On Mon, Jun 24, 2019 at 11:19:13AM -0500, Gustavo A. R. Silva wrote:
> > In preparation to enabling -Wimplicit-fallthrough, mark switch
> > cases where we are expecting to fall through.
> >
> > This patch fixes the following warnings:
> >
> > arch/x86/events/intel/core.c: In function ‘intel_pmu_init’:
> > arch/x86/events/intel/core.c:4959:8: warning: this statement may fall through [-Wimplicit-fallthrough=]
> > pmem = true;
> > ~~~~~^~~~~~
> > arch/x86/events/intel/core.c:4960:2: note: here
> > case INTEL_FAM6_SKYLAKE_MOBILE:
> > ^~~~
> > arch/x86/events/intel/core.c:5008:8: warning: this statement may fall through [-Wimplicit-fallthrough=]
> > pmem = true;
> > ~~~~~^~~~~~
> > arch/x86/events/intel/core.c:5009:2: note: here
> > case INTEL_FAM6_ICELAKE_MOBILE:
> > ^~~~
> >
> > Warning level 3 was used: -Wimplicit-fallthrough=3
> >
> > This patch is part of the ongoing efforts to enable
> > -Wimplicit-fallthrough.
> >
> > Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
>
> I still consider it an abomination that the C parser looks at comments
> -- other than to delete them, but OK I suppose, I'll take it.

I still believe Arnaldo's/Miguel's/Shawn's/my et al. suggestion of

#define __fallthrough __attribute__((fallthrough))

is far better.