Re: [PATCH RESEND 4/4] x86/apic: Fix W=1 build kernel-doc warning

[Ingo Molnar <mingo@kernel.org>]

* Shivank Garg <shivankg@amd.com> wrote:

> 
> 
> On 5/14/2025 1:26 PM, Ingo Molnar wrote:
> > 
> > * Shivank Garg <shivankg@amd.com> wrote:
> > 
> >> Building the kernel with W=1 generates the following warning:
> >>
> >> arch/x86/kernel/apic/apic.c:2140: warning: Function parameter or struct member 'spurious_interrupt' not described in 'DEFINE_IDTENTRY_IRQ'
> >> arch/x86/kernel/apic/apic.c:2140: warning: expecting prototype for spurious_interrupt(). Prototype was for DEFINE_IDTENTRY_IRQ() instead
> >>
> >> Fix the description format to fix the warning.
> >>
> >> Signed-off-by: Shivank Garg <shivankg@amd.com>
> >> ---
> >>  arch/x86/kernel/apic/apic.c | 7 ++++---
> >>  1 file changed, 4 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
> >> index 62584a347931..f888a28d400f 100644
> >> --- a/arch/x86/kernel/apic/apic.c
> >> +++ b/arch/x86/kernel/apic/apic.c
> >> @@ -2128,9 +2128,10 @@ static noinline void handle_spurious_interrupt(u8 vector)
> >>  }
> >>  
> >>  /**
> >> - * spurious_interrupt - Catch all for interrupts raised on unused vectors
> >> - * @regs:	Pointer to pt_regs on stack
> >> - * @vector:	The vector number
> >> + * DEFINE_IDTENTRY_IRQ - Handler for spurious interrupts
> >> + * @spurious_interrupt: Catch all for interrupts raised on unused vectors
> >> + * regs:	Pointer to pt_regs on stack
> >> + * vector:	The vector number
> > 
> > This is incorrect and is based on a misunderstanding of what the code 
> > does:
> > 
> > DEFINE_IDTENTRY_IRQ(spurious_interrupt)
> > {
> >         handle_spurious_interrupt(vector);
> > }
> 
> The kernel-doc tool doesn't handle macros properly.
> Can I change it to a normal comment instead?
> or if a kernel-doc comment is required how should I make it correct?

BTW., kernel-doc could be fixed/extended to work better with macros, 
but I'm not sure it's the right approach in this case: this x86 macro 
*is* obfuscating the real function signature.

We could, perhaps, if the kernel-doc documentation has value, just have 
an additional prototype for the resulting function, right before the 
definition, and document it via kernel-doc.

Something like:

	/**
	 * <kernel-doc annotation>
	 */
	static void __spurious_interrupt(struct pt_regs *regs, u32 vector);

	DEFINE_IDTENTRY_IRQ(spurious_interrupt)
	{
	...

would be the most intuitive outcome IMO, as the trailing part of the 
DEFINE_IDTENTRY_IRQ() definition defines the __spurious_interrupt() 
function.

BTW., note how your kernel-doc annotation has another inaccuracy: the 
function that has the 'vector' parameter which you documented is not 
spurious_interrupt(), but __spurious_interrupt(). The resulting 
spurious_interrupt() function, which is the main entry to the spurious 
interrupts vector, has the following signature:

	extern __visible noinstr void spurious_interrupt(struct pt_regs *regs, unsigned long error_code);

Thanks,

	Ingo