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

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.