Re: [boqun:rust-rcu 14/27] rust/helpers/interrupt.c:17:9: warning: static function 'arch_local_save_flags' is used in an inline function with external linkage

Re: [boqun:rust-rcu 14/27] rust/helpers/interrupt.c:17:9: warning: static function 'arch_local_save_flags' is used in an inline function with external linkage

[Boqun Feng]

[Cc s390]

On Mon, Jul 13, 2026 at 12:45:07PM +0800, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/boqun/linux.git rust-rcu
> head:   dcecd5f6e71e2437c8abe333ee2426fbe63e6398
> commit: 27e30521043c39ca18ea3e28f825f9c7bd30b580 [14/27] rust: Introduce interrupt module
> config: s390-randconfig-002-20260713 (https://download.01.org/0day-ci/archive/20260713/202607131219.euJHPSJ5-lkp@intel.com/config)
> compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
> rustc: rustc 1.96.0 (ac68faa20 2026-05-25)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260713/202607131219.euJHPSJ5-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202607131219.euJHPSJ5-lkp@intel.com/
> 
> All warnings (new ones prefixed by >>):
> 
>    In file included from rust/helpers/helpers.c:68:
> >> rust/helpers/interrupt.c:17:9: warning: static function 'arch_local_save_flags' is used in an inline function with external linkage [-Wstatic-in-inline]
>       17 |         return irqs_disabled();
>          |                ^
>    include/linux/irqflags.h:256:3: note: expanded from macro 'irqs_disabled'
>      256 |                 raw_local_save_flags(_flags);           \
>          |                 ^
>    include/linux/irqflags.h:184:11: note: expanded from macro 'raw_local_save_flags'
>      184 |                 flags = arch_local_save_flags();        \
>          |                         ^
>    rust/helpers/interrupt.c:15:1: note: use 'static' to give inline function 'rust_helper_irqs_disabled' internal linkage
>       15 | __rust_helper bool rust_helper_irqs_disabled(void)
>          | ^
>          | static 
>    rust/helpers/helpers.c:38:23: note: expanded from macro '__rust_helper'
>       38 | #define __rust_helper __always_inline
>          |                       ^
>    include/linux/compiler_attributes.h:55:41: note: expanded from macro '__always_inline'
>       55 | #define __always_inline                 inline __attribute__((__always_inline__))
>          |                                         ^
>    include/linux/compiler_types.h:235:16: note: expanded from macro 'inline'
>      235 | #define inline inline __gnu_inline __inline_maybe_unused notrace
>          |                ^
>    arch/s390/include/asm/irqflags.h:46:48: note: 'arch_local_save_flags' declared here
>       46 | static arch_local_irq_attributes unsigned long arch_local_save_flags(void)
>          |                                                ^
>    1 warning generated.
> --
>    In file included from rust/helpers/helpers.c:68:
> >> rust/helpers/interrupt.c:17:9: warning: static function 'arch_local_save_flags' is used in an inline function with external linkage [-Wstatic-in-inline]
>    17 |         return irqs_disabled();
>    |                ^
>    include/linux/irqflags.h:256:3: note: expanded from macro 'irqs_disabled'
>    256 |                 raw_local_save_flags(_flags);           \
>    |                 ^
>    include/linux/irqflags.h:184:11: note: expanded from macro 'raw_local_save_flags'
>    184 |                 flags = arch_local_save_flags();        \
>    |                         ^
>    rust/helpers/interrupt.c:15:1: note: use 'static' to give inline function 'rust_helper_irqs_disabled' internal linkage
>    15 | __rust_helper bool rust_helper_irqs_disabled(void)
>    | ^
>    | static
>    rust/helpers/helpers.c:38:23: note: expanded from macro '__rust_helper'
>    38 | #define __rust_helper __always_inline
>    |                       ^
>    include/linux/compiler_attributes.h:55:41: note: expanded from macro '__always_inline'
>    55 | #define __always_inline                 inline __attribute__((__always_inline__))
>    |                                         ^
>    include/linux/compiler_types.h:235:16: note: expanded from macro 'inline'
>    235 | #define inline inline __gnu_inline __inline_maybe_unused notrace
>    |                ^
>    arch/s390/include/asm/irqflags.h:46:48: note: 'arch_local_save_flags' declared here
>    46 | static arch_local_irq_attributes unsigned long arch_local_save_flags(void)
>    |                                                ^
>    1 warning generated.
>    warning: 1 warning emitted
> 

This seems not a Rust-only issue to me, basically you got the warning
whenever you have an inline function calling irqs_disabled(). I'm a bit
curious why 1b301f5f28ba ("s390/irqflags: do not instrument
arch_local_irq_*() with KMSAN") wanted to add noinline when KMSAN=y, all
you need is noinstr, no?

Regards,
Boqun

> 
> vim +/arch_local_save_flags +17 rust/helpers/interrupt.c
> 
>     14	
>     15	__rust_helper bool rust_helper_irqs_disabled(void)
>     16	{
>   > 17		return irqs_disabled();
> 
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki

Re: [boqun:rust-rcu 14/27] rust/helpers/interrupt.c:17:9: warning: static function 'arch_local_save_flags' is used in an inline function with external linkage

[Ilya Leoshkevich]

On 7/15/26 21:12, Boqun Feng wrote:
> [Cc s390]
> 
> On Mon, Jul 13, 2026 at 12:45:07PM +0800, kernel test robot wrote:
>> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/boqun/linux.git rust-rcu
>> head:   dcecd5f6e71e2437c8abe333ee2426fbe63e6398
>> commit: 27e30521043c39ca18ea3e28f825f9c7bd30b580 [14/27] rust: Introduce interrupt module
>> config: s390-randconfig-002-20260713 (https://download.01.org/0day-ci/archive/20260713/202607131219.euJHPSJ5-lkp@intel.com/config)
>> compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
>> rustc: rustc 1.96.0 (ac68faa20 2026-05-25)
>> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260713/202607131219.euJHPSJ5-lkp@intel.com/reproduce)
>>
>> If you fix the issue in a separate patch/commit (i.e. not just a new version of
>> the same patch/commit), kindly add following tags
>> | Reported-by: kernel test robot <lkp@intel.com>
>> | Closes: https://lore.kernel.org/oe-kbuild-all/202607131219.euJHPSJ5-lkp@intel.com/
>>
>> All warnings (new ones prefixed by >>):
>>
>>     In file included from rust/helpers/helpers.c:68:
>>>> rust/helpers/interrupt.c:17:9: warning: static function 'arch_local_save_flags' is used in an inline function with external linkage [-Wstatic-in-inline]
>>        17 |         return irqs_disabled();
>>           |                ^
>>     include/linux/irqflags.h:256:3: note: expanded from macro 'irqs_disabled'
>>       256 |                 raw_local_save_flags(_flags);           \
>>           |                 ^
>>     include/linux/irqflags.h:184:11: note: expanded from macro 'raw_local_save_flags'
>>       184 |                 flags = arch_local_save_flags();        \
>>           |                         ^
>>     rust/helpers/interrupt.c:15:1: note: use 'static' to give inline function 'rust_helper_irqs_disabled' internal linkage
>>        15 | __rust_helper bool rust_helper_irqs_disabled(void)
>>           | ^
>>           | static
>>     rust/helpers/helpers.c:38:23: note: expanded from macro '__rust_helper'
>>        38 | #define __rust_helper __always_inline
>>           |                       ^
>>     include/linux/compiler_attributes.h:55:41: note: expanded from macro '__always_inline'
>>        55 | #define __always_inline                 inline __attribute__((__always_inline__))
>>           |                                         ^
>>     include/linux/compiler_types.h:235:16: note: expanded from macro 'inline'
>>       235 | #define inline inline __gnu_inline __inline_maybe_unused notrace
>>           |                ^
>>     arch/s390/include/asm/irqflags.h:46:48: note: 'arch_local_save_flags' declared here
>>        46 | static arch_local_irq_attributes unsigned long arch_local_save_flags(void)
>>           |                                                ^
>>     1 warning generated.
>> --
>>     In file included from rust/helpers/helpers.c:68:
>>>> rust/helpers/interrupt.c:17:9: warning: static function 'arch_local_save_flags' is used in an inline function with external linkage [-Wstatic-in-inline]
>>     17 |         return irqs_disabled();
>>     |                ^
>>     include/linux/irqflags.h:256:3: note: expanded from macro 'irqs_disabled'
>>     256 |                 raw_local_save_flags(_flags);           \
>>     |                 ^
>>     include/linux/irqflags.h:184:11: note: expanded from macro 'raw_local_save_flags'
>>     184 |                 flags = arch_local_save_flags();        \
>>     |                         ^
>>     rust/helpers/interrupt.c:15:1: note: use 'static' to give inline function 'rust_helper_irqs_disabled' internal linkage
>>     15 | __rust_helper bool rust_helper_irqs_disabled(void)
>>     | ^
>>     | static
>>     rust/helpers/helpers.c:38:23: note: expanded from macro '__rust_helper'
>>     38 | #define __rust_helper __always_inline
>>     |                       ^
>>     include/linux/compiler_attributes.h:55:41: note: expanded from macro '__always_inline'
>>     55 | #define __always_inline                 inline __attribute__((__always_inline__))
>>     |                                         ^
>>     include/linux/compiler_types.h:235:16: note: expanded from macro 'inline'
>>     235 | #define inline inline __gnu_inline __inline_maybe_unused notrace
>>     |                ^
>>     arch/s390/include/asm/irqflags.h:46:48: note: 'arch_local_save_flags' declared here
>>     46 | static arch_local_irq_attributes unsigned long arch_local_save_flags(void)
>>     |                                                ^
>>     1 warning generated.
>>     warning: 1 warning emitted
>>
> 
> This seems not a Rust-only issue to me, basically you got the warning
> whenever you have an inline function calling irqs_disabled(). I'm a bit
> curious why 1b301f5f28ba ("s390/irqflags: do not instrument
> arch_local_irq_*() with KMSAN") wanted to add noinline when KMSAN=y, all
> you need is noinstr, no?

Hi,

Unfortunately if a function is inlined, then noinstr is not honored.
The reason for using noinstr for these functions is interaction of
instrumentation with lockdep, so inlining them into non-noinstr callers
breaks KMSAN in a way that is described in the commit message.

Best regards,
Ilya

> 
> Regards,
> Boqun
> 
>>
>> vim +/arch_local_save_flags +17 rust/helpers/interrupt.c
>>
>>      14	
>>      15	__rust_helper bool rust_helper_irqs_disabled(void)
>>      16	{
>>    > 17		return irqs_disabled();
>>
>> --
>> 0-DAY CI Kernel Test Service
>> https://github.com/intel/lkp-tests/wiki

Re: [boqun:rust-rcu 14/27] rust/helpers/interrupt.c:17:9: warning: static function 'arch_local_save_flags' is used in an inline function with external linkage

[Heiko Carstens]

On Wed, Jul 15, 2026 at 12:12:53PM -0700, Boqun Feng wrote:
> [Cc s390]
> >    In file included from rust/helpers/helpers.c:68:
> > >> rust/helpers/interrupt.c:17:9: warning: static function 'arch_local_save_flags' is used in an inline function with external linkage [-Wstatic-in-inline]
> >    17 |         return irqs_disabled();
> >    |                ^
> >    include/linux/irqflags.h:256:3: note: expanded from macro 'irqs_disabled'
> >    256 |                 raw_local_save_flags(_flags);           \
> >    |                 ^
> >    include/linux/irqflags.h:184:11: note: expanded from macro 'raw_local_save_flags'
> >    184 |                 flags = arch_local_save_flags();        \
> >    |                         ^
> >    rust/helpers/interrupt.c:15:1: note: use 'static' to give inline function 'rust_helper_irqs_disabled' internal linkage
> >    15 | __rust_helper bool rust_helper_irqs_disabled(void)
> >    | ^
> >    | static
> >    rust/helpers/helpers.c:38:23: note: expanded from macro '__rust_helper'
> >    38 | #define __rust_helper __always_inline
> >    |                       ^
> >    include/linux/compiler_attributes.h:55:41: note: expanded from macro '__always_inline'
> >    55 | #define __always_inline                 inline __attribute__((__always_inline__))
> >    |                                         ^
> >    include/linux/compiler_types.h:235:16: note: expanded from macro 'inline'
> >    235 | #define inline inline __gnu_inline __inline_maybe_unused notrace
> >    |                ^
> >    arch/s390/include/asm/irqflags.h:46:48: note: 'arch_local_save_flags' declared here
> >    46 | static arch_local_irq_attributes unsigned long arch_local_save_flags(void)
> >    |                                                ^
> >    1 warning generated.
> >    warning: 1 warning emitted
> > 
> 
> This seems not a Rust-only issue to me, basically you got the warning
> whenever you have an inline function calling irqs_disabled(). I'm a bit
> curious why 1b301f5f28ba ("s390/irqflags: do not instrument
> arch_local_irq_*() with KMSAN") wanted to add noinline when KMSAN=y, all
> you need is noinstr, no?

While the combination of __always_inline and noinstr _seems_ to work
with clang, this looks just wrong to me. I guess we really would need
a (single) out-of-line variant of the affected functions in question
for KMSAN.

Ilya, since that was your commit, does that sound sane?

Re: [boqun:rust-rcu 14/27] rust/helpers/interrupt.c:17:9: warning: static function 'arch_local_save_flags' is used in an inline function with external linkage

[Ilya Leoshkevich]

On 7/16/26 13:56, Heiko Carstens wrote:
> On Wed, Jul 15, 2026 at 12:12:53PM -0700, Boqun Feng wrote:
>> [Cc s390]
>>>     In file included from rust/helpers/helpers.c:68:
>>>>> rust/helpers/interrupt.c:17:9: warning: static function 'arch_local_save_flags' is used in an inline function with external linkage [-Wstatic-in-inline]
>>>     17 |         return irqs_disabled();
>>>     |                ^
>>>     include/linux/irqflags.h:256:3: note: expanded from macro 'irqs_disabled'
>>>     256 |                 raw_local_save_flags(_flags);           \
>>>     |                 ^
>>>     include/linux/irqflags.h:184:11: note: expanded from macro 'raw_local_save_flags'
>>>     184 |                 flags = arch_local_save_flags();        \
>>>     |                         ^
>>>     rust/helpers/interrupt.c:15:1: note: use 'static' to give inline function 'rust_helper_irqs_disabled' internal linkage
>>>     15 | __rust_helper bool rust_helper_irqs_disabled(void)
>>>     | ^
>>>     | static
>>>     rust/helpers/helpers.c:38:23: note: expanded from macro '__rust_helper'
>>>     38 | #define __rust_helper __always_inline
>>>     |                       ^
>>>     include/linux/compiler_attributes.h:55:41: note: expanded from macro '__always_inline'
>>>     55 | #define __always_inline                 inline __attribute__((__always_inline__))
>>>     |                                         ^
>>>     include/linux/compiler_types.h:235:16: note: expanded from macro 'inline'
>>>     235 | #define inline inline __gnu_inline __inline_maybe_unused notrace
>>>     |                ^
>>>     arch/s390/include/asm/irqflags.h:46:48: note: 'arch_local_save_flags' declared here
>>>     46 | static arch_local_irq_attributes unsigned long arch_local_save_flags(void)
>>>     |                                                ^
>>>     1 warning generated.
>>>     warning: 1 warning emitted
>>>
>>
>> This seems not a Rust-only issue to me, basically you got the warning
>> whenever you have an inline function calling irqs_disabled(). I'm a bit
>> curious why 1b301f5f28ba ("s390/irqflags: do not instrument
>> arch_local_irq_*() with KMSAN") wanted to add noinline when KMSAN=y, all
>> you need is noinstr, no?
> 
> While the combination of __always_inline and noinstr _seems_ to work
> with clang, this looks just wrong to me. I guess we really would need
> a (single) out-of-line variant of the affected functions in question
> for KMSAN.
> 
> Ilya, since that was your commit, does that sound sane?

Hi, sure, making them out-of-line would make life easier.
I will look into it.