From: Robin Murphy <robin.murphy@arm.com> To: "Rafael J. Wysocki" <rafael@kernel.org>, Lee Jones <lee.jones@linaro.org> Cc: Denis Sadykov <denis.m.sadykov@intel.com>, Andy Grover <andrew.grover@intel.com>, Linux PM <linux-pm@vger.kernel.org>, Viresh Kumar <viresh.kumar@linaro.org>, "Rafael J. Wysocki" <rjw@rjwysocki.net>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>, Linux ARM <linux-arm-kernel@lists.infradead.org>, Dominik Brodowski <linux@brodo.de> Subject: Re: [PATCH 08/13] cpufreq: acpi-cpufreq: Take 'dummy' principle one stage further Date: Tue, 14 Jul 2020 17:20:54 +0100 [thread overview] Message-ID: <8b2f7674-9e33-e09c-cf99-84c59edb9779@arm.com> (raw) In-Reply-To: <CAJZ5v0igiz-VmmDC2qsZ3AhqjGhM54LHMLeLdZ7Dr=h5Dm9Rrg@mail.gmail.com> On 2020-07-14 17:03, Rafael J. Wysocki wrote: > On Tue, Jul 14, 2020 at 4:51 PM Lee Jones <lee.jones@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? Robin. >> 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.grover@intel.com> >> Cc: Paul Diefenbaugh <paul.s.diefenbaugh@intel.com> >> Cc: Dominik Brodowski <linux@brodo.de> >> Cc: Denis Sadykov <denis.m.sadykov@intel.com> >> Signed-off-by: Lee Jones <lee.jones@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; >> } >> >> -- >> 2.25.1 >> > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >
WARNING: multiple messages have this Message-ID (diff)
From: Robin Murphy <robin.murphy@arm.com> To: "Rafael J. Wysocki" <rafael@kernel.org>, Lee Jones <lee.jones@linaro.org> Cc: Denis Sadykov <denis.m.sadykov@intel.com>, Andy Grover <andrew.grover@intel.com>, Linux PM <linux-pm@vger.kernel.org>, Viresh Kumar <viresh.kumar@linaro.org>, "Rafael J. Wysocki" <rjw@rjwysocki.net>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>, Linux ARM <linux-arm-kernel@lists.infradead.org>, Dominik Brodowski <linux@brodo.de> Subject: Re: [PATCH 08/13] cpufreq: acpi-cpufreq: Take 'dummy' principle one stage further Date: Tue, 14 Jul 2020 17:20:54 +0100 [thread overview] Message-ID: <8b2f7674-9e33-e09c-cf99-84c59edb9779@arm.com> (raw) In-Reply-To: <CAJZ5v0igiz-VmmDC2qsZ3AhqjGhM54LHMLeLdZ7Dr=h5Dm9Rrg@mail.gmail.com> On 2020-07-14 17:03, Rafael J. Wysocki wrote: > On Tue, Jul 14, 2020 at 4:51 PM Lee Jones <lee.jones@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? Robin. >> 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.grover@intel.com> >> Cc: Paul Diefenbaugh <paul.s.diefenbaugh@intel.com> >> Cc: Dominik Brodowski <linux@brodo.de> >> Cc: Denis Sadykov <denis.m.sadykov@intel.com> >> Signed-off-by: Lee Jones <lee.jones@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; >> } >> >> -- >> 2.25.1 >> > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-07-14 16:20 UTC|newest] Thread overview: 150+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-07-14 14:50 [PATCH 00/13] Rid W=1 warnings in CPUFreq Lee Jones 2020-07-14 14:50 ` Lee Jones 2020-07-14 14:50 ` [PATCH 01/13] cpufreq: freq_table: Demote obvious misuse of kerneldoc to standard comment blocks Lee Jones 2020-07-14 14:50 ` Lee Jones 2020-07-15 2:44 ` Viresh Kumar 2020-07-15 2:44 ` Viresh Kumar 2020-07-14 14:50 ` [PATCH 02/13] cpufreq: cpufreq: Demote lots of function headers unworthy of kerneldoc status Lee Jones 2020-07-14 14:50 ` Lee Jones 2020-07-15 2:49 ` Viresh Kumar 2020-07-15 2:49 ` Viresh Kumar 2020-07-15 6:47 ` Lee Jones 2020-07-15 6:47 ` Lee Jones 2020-07-15 7:09 ` Viresh Kumar 2020-07-15 7:09 ` Viresh Kumar 2020-07-14 14:50 ` [PATCH 03/13] cpufreq: cpufreq_governor: Demote store_sampling_rate() header to standard comment block Lee Jones 2020-07-14 14:50 ` Lee Jones 2020-07-15 2:52 ` Viresh Kumar 2020-07-15 2:52 ` Viresh Kumar 2020-07-15 6:45 ` Lee Jones 2020-07-15 6:45 ` Lee Jones 2020-07-15 7:08 ` Viresh Kumar 2020-07-15 7:08 ` Viresh Kumar 2020-07-15 7:31 ` Lee Jones 2020-07-15 7:31 ` Lee Jones 2020-07-15 8:02 ` Viresh Kumar 2020-07-15 8:02 ` Viresh Kumar 2020-07-15 8:15 ` Lee Jones 2020-07-15 8:15 ` Lee Jones 2020-07-14 14:50 ` [PATCH 04/13] cpufreq: sti-cpufreq: Fix some formatting and misspelling issues Lee Jones 2020-07-14 14:50 ` Lee Jones 2020-07-15 2:58 ` Viresh Kumar 2020-07-15 2:58 ` Viresh Kumar 2020-07-14 14:50 ` [PATCH 05/13] cpufreq/arch: powerpc: pasemi: Move prototypes to shared header Lee Jones 2020-07-14 14:50 ` Lee Jones 2020-07-14 14:50 ` Lee Jones 2020-07-15 3:07 ` Viresh Kumar 2020-07-15 3:07 ` Viresh Kumar 2020-07-15 3:07 ` Viresh Kumar 2020-07-15 3:49 ` Olof Johansson 2020-07-15 3:49 ` Olof Johansson 2020-07-15 3:49 ` Olof Johansson 2020-07-15 3:51 ` Viresh Kumar 2020-07-15 3:51 ` Viresh Kumar 2020-07-15 3:51 ` Viresh Kumar 2020-07-15 6:36 ` Lee Jones 2020-07-15 6:36 ` Lee Jones 2020-07-15 6:36 ` Lee Jones 2020-07-15 6:39 ` Viresh Kumar 2020-07-15 6:39 ` Viresh Kumar 2020-07-15 6:39 ` Viresh Kumar 2020-07-15 3:26 ` Olof Johansson 2020-07-15 3:26 ` Olof Johansson 2020-07-15 3:26 ` Olof Johansson 2020-07-15 6:33 ` Lee Jones 2020-07-15 6:33 ` Lee Jones 2020-07-15 6:33 ` Lee Jones 2020-07-15 6:46 ` Olof Johansson 2020-07-15 6:46 ` Olof Johansson 2020-07-15 6:46 ` Olof Johansson 2020-07-15 7:33 ` Lee Jones 2020-07-15 7:33 ` Lee Jones 2020-07-15 7:33 ` Lee Jones 2020-07-14 14:50 ` [PATCH 06/13] cpufreq: powernv-cpufreq: Functions only used in call-backs should be static Lee Jones 2020-07-14 14:50 ` Lee Jones 2020-07-14 14:50 ` Lee Jones 2020-07-15 3:07 ` Viresh Kumar 2020-07-15 3:07 ` Viresh Kumar 2020-07-15 3:07 ` Viresh Kumar 2020-07-14 14:50 ` [PATCH 07/13] cpufreq: powernv-cpufreq: Fix a bunch of kerneldoc related issues Lee Jones 2020-07-14 14:50 ` Lee Jones 2020-07-14 14:50 ` Lee Jones 2020-07-15 3:09 ` Viresh Kumar 2020-07-15 3:09 ` Viresh Kumar 2020-07-15 3:09 ` Viresh Kumar 2020-07-14 14:50 ` [PATCH 08/13] cpufreq: acpi-cpufreq: Take 'dummy' principle one stage further Lee Jones 2020-07-14 14:50 ` Lee Jones 2020-07-14 16:03 ` Rafael J. Wysocki 2020-07-14 16:03 ` Rafael J. Wysocki 2020-07-14 16:20 ` Robin Murphy [this message] 2020-07-14 16:20 ` Robin Murphy 2020-07-14 21:00 ` Lee Jones 2020-07-14 21:00 ` Lee Jones 2020-07-14 14:50 ` [PATCH 09/13] cpufreq: acpi-cpufreq: Remove unused ID structs Lee Jones 2020-07-14 14:50 ` Lee Jones 2020-07-14 15:58 ` Rafael J. Wysocki 2020-07-14 15:58 ` Rafael J. Wysocki 2020-07-14 21:03 ` Lee Jones 2020-07-14 21:03 ` Lee Jones 2020-07-15 3:24 ` Viresh Kumar 2020-07-15 3:24 ` Viresh Kumar 2020-07-15 3:27 ` Viresh Kumar 2020-07-15 3:27 ` Viresh Kumar 2020-07-15 6:37 ` Lee Jones 2020-07-15 6:37 ` Lee Jones 2020-07-15 11:27 ` Rafael J. Wysocki 2020-07-15 11:27 ` Rafael J. Wysocki 2020-07-15 11:34 ` Lee Jones 2020-07-15 11:34 ` Lee Jones 2020-07-15 11:44 ` Rafael J. Wysocki 2020-07-15 11:44 ` Rafael J. Wysocki 2020-07-15 11:50 ` Lee Jones 2020-07-15 11:50 ` Lee Jones 2020-07-15 12:07 ` Lee Jones 2020-07-15 12:07 ` Lee Jones 2020-07-15 12:11 ` Rafael J. Wysocki 2020-07-15 12:11 ` Rafael J. Wysocki 2020-07-15 12:09 ` Rafael J. Wysocki 2020-07-15 12:09 ` Rafael J. Wysocki 2020-07-15 12:16 ` Lee Jones 2020-07-15 12:16 ` Lee Jones 2020-07-15 12:30 ` Robin Murphy 2020-07-15 12:30 ` Robin Murphy 2020-07-15 12:38 ` Lee Jones 2020-07-15 12:38 ` Lee Jones 2020-07-14 14:50 ` [PATCH 10/13] cpufreq: powernow-k8: Make use of known set but not used variables Lee Jones 2020-07-14 14:50 ` Lee Jones 2020-07-14 17:43 ` Rafael J. Wysocki 2020-07-14 17:43 ` Rafael J. Wysocki 2020-07-14 21:01 ` Lee Jones 2020-07-14 21:01 ` Lee Jones 2020-07-14 14:50 ` [PATCH 11/13] cpufreq: pcc-cpufreq: Remove unused ID structs Lee Jones 2020-07-14 14:50 ` Lee Jones 2020-07-14 17:42 ` Rafael J. Wysocki 2020-07-14 17:42 ` Rafael J. Wysocki 2020-07-14 14:50 ` [PATCH 12/13] cpufreq: intel_pstate: Supply struct attribute description for get_aperf_mperf_shift() Lee Jones 2020-07-14 14:50 ` Lee Jones 2020-07-14 16:35 ` Rafael J. Wysocki 2020-07-14 16:35 ` Rafael J. Wysocki 2020-07-14 21:03 ` Lee Jones 2020-07-14 21:03 ` Lee Jones 2020-07-15 12:38 ` Rafael J. Wysocki 2020-07-15 12:38 ` Rafael J. Wysocki 2020-07-14 14:50 ` [PATCH 13/13] cpufreq: amd_freq_sensitivity: Remove unused ID structs Lee Jones 2020-07-14 14:50 ` Lee Jones 2020-07-14 17:15 ` Kim Phillips 2020-07-14 17:15 ` Kim Phillips 2020-07-14 21:02 ` Lee Jones 2020-07-14 21:02 ` Lee Jones 2020-07-14 21:13 ` Kim Phillips 2020-07-14 21:13 ` Kim Phillips 2020-07-15 6:47 ` Lee Jones 2020-07-15 6:47 ` Lee Jones 2020-07-15 3:36 ` [PATCH 00/13] Rid W=1 warnings in CPUFreq Viresh Kumar 2020-07-15 3:36 ` Viresh Kumar 2020-07-15 6:32 ` Lee Jones 2020-07-15 6:32 ` Lee Jones 2020-07-15 6:38 ` Viresh Kumar 2020-07-15 6:38 ` Viresh Kumar 2020-07-15 7:34 ` Lee Jones 2020-07-15 7:34 ` Lee Jones
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