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Date: Tue, 25 Aug 2020 14:26:05 +0300 From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com> To: Valentin Schneider <valentin.schneider@....com> Cc: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>, Vincent Guittot <vincent.guittot@...aro.org>, linux-kernel@...r.kernel.org, Dietmar Eggemann <dietmar.eggemann@....com> Subject: Re: [PATCH v1] sched/topology: Make compiler happy about unused constant definitions On Tue, Aug 25, 2020 at 02:24:05PM +0300, Andy Shevchenko wrote: > On Tue, Aug 25, 2020 at 11:12:21AM +0100, Valentin Schneider wrote: > > On 25/08/20 10:03, Valentin Schneider wrote: > > > On 25/08/20 09:26, Andy Shevchenko wrote: > > >> On Mon, Aug 24, 2020 at 06:09:41PM +0100, Valentin Schneider wrote: > > >>> On 24/08/20 16:39, Andy Shevchenko wrote: > > >>> > Compilation of almost each file ends up with > > >>> > > > >>> > In file included from .../include/linux/energy_model.h:10, > > >>> > from .../include/linux/device.h:16, > > >>> > from .../drivers/spi/spi.c:8: > > >>> > .../include/linux/sched/topology.h:30:27: warning: ‘SD_DEGENERATE_GROUPS_MASK’ defined but not used [-Wunused-const-variable=] > > >>> > 30 | static const unsigned int SD_DEGENERATE_GROUPS_MASK = > > >>> > | ^~~~~~~~~~~~~~~~~~~~~~~~~ > > >>> > ... > > >>> > > > >>> > Make compiler happy by annotating the static constants with __maybwe_unused. > > > > > Sorry, that's what I get for trying to be too succinct; what I tried to say > > > was that SD_DEGENERATE_GROUPS_MASK should very much be used for SMP. If the > > > build is !SMP, it shouldn't even be defined, IOW I'm perplexed as to where > > > this is coming from. > > > > So I see how having this as a constvar rather than a constexpr is somewhat > > daft (we get an instance per compilation unit), but none of my compilers > > seem to complain (even with W=1). AFAIA the kernelbot didn't catch any of > > it either. > > > > Out of curiosity, what's your compiler & compiler version? > > % gcc --version > gcc (Debian 10.2.0-5) 10.2.0 > > % make O=... W=1 C=1 CF=-D__CHECK_ENDIAN__ -j64 > > > Alternatively we can make this a "proper" constant expression with the > > below. > > It doesn't fix another static const in the same file, though that one requires > DEBUG_SCHED to be enabled. > > Do you want me to split this fix and fix only the other case? Just checked and the other case has been brought by b6e862f38672 ("sched/topology: Define and assign sched_domain flag metadata") with your authorship. -- With Best Regards, Andy Shevchenko
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