* [PATCH] mfd: kempld-core: Mark kempld-acpi_table as __maybe_unused @ 2020-10-01 9:52 Michael Brunner 2020-10-02 7:01 ` Lee Jones 0 siblings, 1 reply; 6+ messages in thread From: Michael Brunner @ 2020-10-01 9:52 UTC (permalink / raw) To: lee.jones; +Cc: mibru, linux-kernel The Intel 0-DAY CI Kernel Test Service reports an unused variable warning when compiling with clang for PowerPC: >> drivers/mfd/kempld-core.c:556:36: warning: unused variable 'kempld_acpi_table' [-Wunused-const-variable] static const struct acpi_device_id kempld_acpi_table[] = { The issue can be fixed by marking kempld_acpi_table as __maybe_unused. Fixes: e8299c7313af ("[PATCH] mfd: Add ACPI support to Kontron PLD driver") Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Michael Brunner <michael.brunner@kontron.com> --- drivers/mfd/kempld-core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/mfd/kempld-core.c b/drivers/mfd/kempld-core.c index 1dfe556df038..273481dfaad4 100644 --- a/drivers/mfd/kempld-core.c +++ b/drivers/mfd/kempld-core.c @@ -553,7 +553,7 @@ static int kempld_remove(struct platform_device *pdev) return 0; } -static const struct acpi_device_id kempld_acpi_table[] = { +static const struct acpi_device_id __maybe_unused kempld_acpi_table[] = { { "KEM0001", (kernel_ulong_t)&kempld_platform_data_generic }, {} }; -- 2.25.1 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] mfd: kempld-core: Mark kempld-acpi_table as __maybe_unused 2020-10-01 9:52 [PATCH] mfd: kempld-core: Mark kempld-acpi_table as __maybe_unused Michael Brunner @ 2020-10-02 7:01 ` Lee Jones 2020-10-05 7:07 ` Michael Brunner 0 siblings, 1 reply; 6+ messages in thread From: Lee Jones @ 2020-10-02 7:01 UTC (permalink / raw) To: Michael Brunner; +Cc: mibru, linux-kernel On Thu, 01 Oct 2020, Michael Brunner wrote: > The Intel 0-DAY CI Kernel Test Service reports an unused variable > warning when compiling with clang for PowerPC: > > >> drivers/mfd/kempld-core.c:556:36: warning: unused variable 'kempld_acpi_table' [-Wunused-const-variable] > static const struct acpi_device_id kempld_acpi_table[] = { > > The issue can be fixed by marking kempld_acpi_table as __maybe_unused. > > Fixes: e8299c7313af ("[PATCH] mfd: Add ACPI support to Kontron PLD driver") > > Reported-by: kernel test robot <lkp@intel.com> > Signed-off-by: Michael Brunner <michael.brunner@kontron.com> > --- > drivers/mfd/kempld-core.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/mfd/kempld-core.c b/drivers/mfd/kempld-core.c > index 1dfe556df038..273481dfaad4 100644 > --- a/drivers/mfd/kempld-core.c > +++ b/drivers/mfd/kempld-core.c > @@ -553,7 +553,7 @@ static int kempld_remove(struct platform_device *pdev) > return 0; > } > > -static const struct acpi_device_id kempld_acpi_table[] = { > +static const struct acpi_device_id __maybe_unused kempld_acpi_table[] = { > { "KEM0001", (kernel_ulong_t)&kempld_platform_data_generic }, > {} > }; This is not the right fix. Better just to compile it out completely in these circumstances. I already have a fix for this in soak. -- Lee Jones [李琼斯] Senior Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] mfd: kempld-core: Mark kempld-acpi_table as __maybe_unused 2020-10-02 7:01 ` Lee Jones @ 2020-10-05 7:07 ` Michael Brunner 2020-10-06 6:53 ` Lee Jones 0 siblings, 1 reply; 6+ messages in thread From: Michael Brunner @ 2020-10-05 7:07 UTC (permalink / raw) To: lee.jones; +Cc: mibru, linux-kernel On Fri, 2020-10-02 at 08:01 +0100, Lee Jones wrote: > On Thu, 01 Oct 2020, Michael Brunner wrote: > > > The Intel 0-DAY CI Kernel Test Service reports an unused variable > > warning when compiling with clang for PowerPC: > > > > > > drivers/mfd/kempld-core.c:556:36: warning: unused variable > > > > 'kempld_acpi_table' [-Wunused-const-variable] > > static const struct acpi_device_id kempld_acpi_table[] = { > > > > The issue can be fixed by marking kempld_acpi_table as > > __maybe_unused. > > > > Fixes: e8299c7313af ("[PATCH] mfd: Add ACPI support to Kontron PLD > > driver") > > > > Reported-by: kernel test robot <lkp@intel.com> > > Signed-off-by: Michael Brunner <michael.brunner@kontron.com> > > --- > > drivers/mfd/kempld-core.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/mfd/kempld-core.c b/drivers/mfd/kempld-core.c > > index 1dfe556df038..273481dfaad4 100644 > > --- a/drivers/mfd/kempld-core.c > > +++ b/drivers/mfd/kempld-core.c > > @@ -553,7 +553,7 @@ static int kempld_remove(struct platform_device > > *pdev) > > return 0; > > } > > > > -static const struct acpi_device_id kempld_acpi_table[] = { > > +static const struct acpi_device_id __maybe_unused > > kempld_acpi_table[] = { > > { "KEM0001", (kernel_ulong_t)&kempld_platform_data_generic }, > > {} > > }; > > This is not the right fix. Better just to compile it out completely > in these circumstances. I already have a fix for this in soak. Ok - thank you for the other fix you submitted! But just out of curiosity - in process/coding-style.rst is written that __maybe_unused should be preferred over wrapping in preprocessor conditionals, if a function or variable may potentially go unused in a particular configuration. So why is my patch not the right one here? At least in my tests it seemed to solve the issue. Thanks, Michael ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] mfd: kempld-core: Mark kempld-acpi_table as __maybe_unused 2020-10-05 7:07 ` Michael Brunner @ 2020-10-06 6:53 ` Lee Jones 2020-10-06 15:54 ` Michael Brunner 0 siblings, 1 reply; 6+ messages in thread From: Lee Jones @ 2020-10-06 6:53 UTC (permalink / raw) To: Michael Brunner; +Cc: mibru, linux-kernel On Mon, 05 Oct 2020, Michael Brunner wrote: > On Fri, 2020-10-02 at 08:01 +0100, Lee Jones wrote: > > On Thu, 01 Oct 2020, Michael Brunner wrote: > > > > > The Intel 0-DAY CI Kernel Test Service reports an unused variable > > > warning when compiling with clang for PowerPC: > > > > > > > > drivers/mfd/kempld-core.c:556:36: warning: unused variable > > > > > 'kempld_acpi_table' [-Wunused-const-variable] > > > static const struct acpi_device_id kempld_acpi_table[] = { > > > > > > The issue can be fixed by marking kempld_acpi_table as > > > __maybe_unused. > > > > > > Fixes: e8299c7313af ("[PATCH] mfd: Add ACPI support to Kontron PLD > > > driver") > > > > > > Reported-by: kernel test robot <lkp@intel.com> > > > Signed-off-by: Michael Brunner <michael.brunner@kontron.com> > > > --- > > > drivers/mfd/kempld-core.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/mfd/kempld-core.c b/drivers/mfd/kempld-core.c > > > index 1dfe556df038..273481dfaad4 100644 > > > --- a/drivers/mfd/kempld-core.c > > > +++ b/drivers/mfd/kempld-core.c > > > @@ -553,7 +553,7 @@ static int kempld_remove(struct platform_device > > > *pdev) > > > return 0; > > > } > > > > > > -static const struct acpi_device_id kempld_acpi_table[] = { > > > +static const struct acpi_device_id __maybe_unused > > > kempld_acpi_table[] = { > > > { "KEM0001", (kernel_ulong_t)&kempld_platform_data_generic }, > > > {} > > > }; > > > > This is not the right fix. Better just to compile it out completely > > in these circumstances. I already have a fix for this in soak. > > Ok - thank you for the other fix you submitted! > > But just out of curiosity - in process/coding-style.rst is written that > __maybe_unused should be preferred over wrapping in preprocessor > conditionals, if a function or variable may potentially go unused in a > particular configuration. So why is my patch not the right one here? At > least in my tests it seemed to solve the issue. It's a bone of contention for sure. In these kinds of scenarios (i.e. ACPI and OF tables) it is way more common to wrap them: $ git grep -B3 'acpi_device_id\|of_device_id' | grep 'CONFIG_ACPI\|CONFIG_OF' | wc -l 596 $ git grep -B3 'acpi_device_id\|of_device_id' | grep __maybe_unused | wc -l 63 Parsing them out completely, also has the benefit of saving space, reducing the size of the finalised binary. -- Lee Jones [李琼斯] Senior Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] mfd: kempld-core: Mark kempld-acpi_table as __maybe_unused 2020-10-06 6:53 ` Lee Jones @ 2020-10-06 15:54 ` Michael Brunner 2020-10-07 7:10 ` Lee Jones 0 siblings, 1 reply; 6+ messages in thread From: Michael Brunner @ 2020-10-06 15:54 UTC (permalink / raw) To: lee.jones; +Cc: mibru, linux-kernel On Tue, 2020-10-06 at 07:53 +0100, Lee Jones wrote: > On Mon, 05 Oct 2020, Michael Brunner wrote: > > > On Fri, 2020-10-02 at 08:01 +0100, Lee Jones wrote: > > > On Thu, 01 Oct 2020, Michael Brunner wrote: > > > > > > > The Intel 0-DAY CI Kernel Test Service reports an unused variable > > > > warning when compiling with clang for PowerPC: > > > > > > > > > > drivers/mfd/kempld-core.c:556:36: warning: unused variable > > > > > > 'kempld_acpi_table' [-Wunused-const-variable] > > > > static const struct acpi_device_id kempld_acpi_table[] = { > > > > > > > > The issue can be fixed by marking kempld_acpi_table as > > > > __maybe_unused. > > > > > > > > Fixes: e8299c7313af ("[PATCH] mfd: Add ACPI support to Kontron PLD > > > > driver") > > > > > > > > Reported-by: kernel test robot <lkp@intel.com> > > > > Signed-off-by: Michael Brunner <michael.brunner@kontron.com> > > > > --- > > > > drivers/mfd/kempld-core.c | 2 +- > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/mfd/kempld-core.c b/drivers/mfd/kempld-core.c > > > > index 1dfe556df038..273481dfaad4 100644 > > > > --- a/drivers/mfd/kempld-core.c > > > > +++ b/drivers/mfd/kempld-core.c > > > > @@ -553,7 +553,7 @@ static int kempld_remove(struct platform_device > > > > *pdev) > > > > return 0; > > > > } > > > > > > > > -static const struct acpi_device_id kempld_acpi_table[] = { > > > > +static const struct acpi_device_id __maybe_unused > > > > kempld_acpi_table[] = { > > > > { "KEM0001", (kernel_ulong_t)&kempld_platform_data_generic }, > > > > {} > > > > }; > > > > > > This is not the right fix. Better just to compile it out completely > > > in these circumstances. I already have a fix for this in soak. > > > > Ok - thank you for the other fix you submitted! > > > > But just out of curiosity - in process/coding-style.rst is written that > > __maybe_unused should be preferred over wrapping in preprocessor > > conditionals, if a function or variable may potentially go unused in a > > particular configuration. So why is my patch not the right one here? At > > least in my tests it seemed to solve the issue. > > It's a bone of contention for sure. In these kinds of scenarios > (i.e. ACPI and OF tables) it is way more common to wrap them: > > $ git grep -B3 'acpi_device_id\|of_device_id' | grep 'CONFIG_ACPI\|CONFIG_OF' | wc -l > 596 > $ git grep -B3 'acpi_device_id\|of_device_id' | grep __maybe_unused | wc -l > 63 > > Parsing them out completely, also has the benefit of saving space, > reducing the size of the finalised binary. Doesn't the compiler remove it anyway? At least in my test I didn't see a difference in the resulting object files. Doing a crosscheck, by adding __attribute__((used)) to the definition of kempld_acpi_table, the object file size increased and kempld_acpi_table showed up in the symbol table. Nevertheless, I don't want to start a discussion. I am fine with using the preprocessor. Just wanted to make sure I understand the technical implications of both solutions. Thank you for your time! Best regards, Michael ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] mfd: kempld-core: Mark kempld-acpi_table as __maybe_unused 2020-10-06 15:54 ` Michael Brunner @ 2020-10-07 7:10 ` Lee Jones 0 siblings, 0 replies; 6+ messages in thread From: Lee Jones @ 2020-10-07 7:10 UTC (permalink / raw) To: Michael Brunner; +Cc: mibru, linux-kernel On Tue, 06 Oct 2020, Michael Brunner wrote: > On Tue, 2020-10-06 at 07:53 +0100, Lee Jones wrote: > > On Mon, 05 Oct 2020, Michael Brunner wrote: > > > > > On Fri, 2020-10-02 at 08:01 +0100, Lee Jones wrote: > > > > On Thu, 01 Oct 2020, Michael Brunner wrote: > > > > > > > > > The Intel 0-DAY CI Kernel Test Service reports an unused variable > > > > > warning when compiling with clang for PowerPC: > > > > > > > > > > > > drivers/mfd/kempld-core.c:556:36: warning: unused variable > > > > > > > 'kempld_acpi_table' [-Wunused-const-variable] > > > > > static const struct acpi_device_id kempld_acpi_table[] = { > > > > > > > > > > The issue can be fixed by marking kempld_acpi_table as > > > > > __maybe_unused. > > > > > > > > > > Fixes: e8299c7313af ("[PATCH] mfd: Add ACPI support to Kontron PLD > > > > > driver") > > > > > > > > > > Reported-by: kernel test robot <lkp@intel.com> > > > > > Signed-off-by: Michael Brunner <michael.brunner@kontron.com> > > > > > --- > > > > > drivers/mfd/kempld-core.c | 2 +- > > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > > > diff --git a/drivers/mfd/kempld-core.c b/drivers/mfd/kempld-core.c > > > > > index 1dfe556df038..273481dfaad4 100644 > > > > > --- a/drivers/mfd/kempld-core.c > > > > > +++ b/drivers/mfd/kempld-core.c > > > > > @@ -553,7 +553,7 @@ static int kempld_remove(struct platform_device > > > > > *pdev) > > > > > return 0; > > > > > } > > > > > > > > > > -static const struct acpi_device_id kempld_acpi_table[] = { > > > > > +static const struct acpi_device_id __maybe_unused > > > > > kempld_acpi_table[] = { > > > > > { "KEM0001", (kernel_ulong_t)&kempld_platform_data_generic }, > > > > > {} > > > > > }; > > > > > > > > This is not the right fix. Better just to compile it out completely > > > > in these circumstances. I already have a fix for this in soak. > > > > > > Ok - thank you for the other fix you submitted! > > > > > > But just out of curiosity - in process/coding-style.rst is written that > > > __maybe_unused should be preferred over wrapping in preprocessor > > > conditionals, if a function or variable may potentially go unused in a > > > particular configuration. So why is my patch not the right one here? At > > > least in my tests it seemed to solve the issue. > > > > It's a bone of contention for sure. In these kinds of scenarios > > (i.e. ACPI and OF tables) it is way more common to wrap them: > > > > $ git grep -B3 'acpi_device_id\|of_device_id' | grep 'CONFIG_ACPI\|CONFIG_OF' | wc -l > > 596 > > $ git grep -B3 'acpi_device_id\|of_device_id' | grep __maybe_unused | wc -l > > 63 > > > > Parsing them out completely, also has the benefit of saving space, > > reducing the size of the finalised binary. > > Doesn't the compiler remove it anyway? At least in my test I didn't see > a difference in the resulting object files. > Doing a crosscheck, by adding __attribute__((used)) to the definition > of kempld_acpi_table, the object file size increased and > kempld_acpi_table showed up in the symbol table. > > Nevertheless, I don't want to start a discussion. I am fine with using > the preprocessor. Just wanted to make sure I understand the technical > implications of both solutions. This is what happened last time I submitted a patch using __maybe_unused: https://lkml.org/lkml/2020/8/17/1704 -- Lee Jones [李琼斯] Senior Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2020-10-07 7:10 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-10-01 9:52 [PATCH] mfd: kempld-core: Mark kempld-acpi_table as __maybe_unused Michael Brunner 2020-10-02 7:01 ` Lee Jones 2020-10-05 7:07 ` Michael Brunner 2020-10-06 6:53 ` Lee Jones 2020-10-06 15:54 ` Michael Brunner 2020-10-07 7:10 ` Lee Jones
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).