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Date: Tue, 25 Aug 2020 13:00:12 +0100 From: Valentin Schneider <valentin.schneider@....com> To: Andy Shevchenko <andriy.shevchenko@...ux.intel.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 25/08/20 12:32, Andy Shevchenko wrote: > On Tue, Aug 25, 2020 at 02:26:05PM +0300, Andy Shevchenko wrote: >> 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. > > And even without compiler or any other analyzer / bot I can 100% sure tell that > spi.c does *not* use that symbol. Aye aye, this is a daft constvar placement from my end, apologies. For the SD_DEGENERATE_GROUPS_MASK, that one could directly be shoved into kernel/sched/topology.c (or done via an enum, I don't care too much). I suppose the other one causing you grief is sd_flag_debug[]; that one too really shouldn't be in a header. I need to access that in two separate files, so I guess I'll have to cook up some wrappers. Let me take a jab at it, it's my own mess after all...
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