On Tue, 14 Jul 2020, Robin Murphy wrote: > On 2020-07-14 17:03, Rafael J. Wysocki wrote: > > On Tue, Jul 14, 2020 at 4:51 PM Lee Jones <lee.jo...@linaro.org> wrote: > > > > > > If we fail to use a variable, even a 'dummy' one, then the compiler > > > complains that it is set but not used. We know this is fine, so we > > > set it to its own value here. > > > > Which is kind of ugly in my personal view. I hope that the compiler > > will actually optimize the extra code away ... > > > > > Fixes the following W=1 kernel build warning(s): > > > > Well, "Makes the following ... warning(s) go away:" rather ... > > Isn't that what we have __maybe_unused and __always_unused for?
Yes, that would be better. I didn't know you could do that with standard variables. Will fix. > > > drivers/cpufreq/acpi-cpufreq.c: In function ‘cpu_freq_read_intel’: > > > drivers/cpufreq/acpi-cpufreq.c:247:11: warning: variable ‘dummy’ set > > > but not used [-Wunused-but-set-variable] > > > drivers/cpufreq/acpi-cpufreq.c: In function ‘cpu_freq_read_amd’: > > > drivers/cpufreq/acpi-cpufreq.c:265:11: warning: variable ‘dummy’ set > > > but not used [-Wunused-but-set-variable] > > > > > > Cc: Andy Grover <andrew.gro...@intel.com> > > > Cc: Paul Diefenbaugh <paul.s.diefenba...@intel.com> > > > Cc: Dominik Brodowski <li...@brodo.de> > > > Cc: Denis Sadykov <denis.m.sady...@intel.com> > > > Signed-off-by: Lee Jones <lee.jo...@linaro.org> > > > --- > > > drivers/cpufreq/acpi-cpufreq.c | 2 ++ > > > 1 file changed, 2 insertions(+) > > > > > > diff --git a/drivers/cpufreq/acpi-cpufreq.c > > > b/drivers/cpufreq/acpi-cpufreq.c > > > index 429e5a36c08a9..d38a693b48e03 100644 > > > --- a/drivers/cpufreq/acpi-cpufreq.c > > > +++ b/drivers/cpufreq/acpi-cpufreq.c > > > @@ -247,6 +247,7 @@ static u32 cpu_freq_read_intel(struct > > > acpi_pct_register *not_used) > > > u32 val, dummy; > > > > > > rdmsr(MSR_IA32_PERF_CTL, val, dummy); > > > + dummy &= dummy; /* Silence set but not used warning */ > > > return val; > > > } > > > > > > @@ -264,6 +265,7 @@ static u32 cpu_freq_read_amd(struct acpi_pct_register > > > *not_used) > > > u32 val, dummy; > > > > > > rdmsr(MSR_AMD_PERF_CTL, val, dummy); > > > + dummy &= dummy; /* Silence set but not used warning */ > > > return val; > > > } > > > > > > > _______________________________________________ > > linux-arm-kernel mailing list > > linux-arm-ker...@lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > > -- Lee Jones [李琼斯] Senior Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog
