linux-kernel - Re: [PATCH v2 6/8] powerpc: Prepare for IRQ entry exit

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Message-ID: <33v3ncxlwtc5qfdc257hky7pnly5j445qaqzc45vnbiswnge4t@wx5nujnzrazh>
Date: Wed, 17 Dec 2025 10:13:19 +0530
From: Mukesh Kumar Chaurasiya <mkchauras@...ux.ibm.com>
To: "Christophe Leroy (CS GROUP)" <chleroy@...nel.org>
Cc: maddy@...ux.ibm.com, mpe@...erman.id.au, npiggin@...il.com,
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Subject: Re: [PATCH v2 6/8] powerpc: Prepare for IRQ entry exit

On Tue, Dec 16, 2025 at 11:40:51PM +0100, Christophe Leroy (CS GROUP) wrote:
> 
> 
> Le 16/12/2025 à 16:00, Mukesh Kumar Chaurasiya a écrit :
> > On Tue, Dec 16, 2025 at 10:58:16AM +0100, Christophe Leroy (CS GROUP) wrote:
> > > 
> > > 
> > > Le 14/12/2025 à 14:02, Mukesh Kumar Chaurasiya a écrit :
> > > > From: Mukesh Kumar Chaurasiya <mchauras@...ux.ibm.com>
> > > > 
> > > > Move interrupt entry and exit helper routines from interrupt.h into the
> > > > PowerPC-specific entry-common.h header as a preparatory step for enabling
> > > > the generic entry/exit framework.
> > > > 
> > > > This consolidation places all PowerPC interrupt entry/exit handling in a
> > > > single common header, aligning with the generic entry infrastructure.
> > > > The helpers provide architecture-specific handling for interrupt and NMI
> > > > entry/exit sequences, including:
> > > > 
> > > >    - arch_interrupt_enter/exit_prepare()
> > > >    - arch_interrupt_async_enter/exit_prepare()
> > > >    - arch_interrupt_nmi_enter/exit_prepare()
> > > >    - Supporting helpers such as nap_adjust_return(), check_return_regs_valid(),
> > > >      debug register maintenance, and soft mask handling.
> > > > 
> > > > The functions are copied verbatim from interrupt.h to avoid functional
> > > > changes at this stage. Subsequent patches will integrate these routines
> > > > into the generic entry/exit flow.
> > > 
> > > Can we move them instead of duplicating them ?
> > > 
> > Till we enable the Generic framework i didn't want to touch the already
> > used code path. Once we enable the code all the unused code should be
> > removed. This helps us in bisecting future issues caused due to this.
> 
> I can't see who it can help bisecting. What did I miss ?
> 
> If you copy the code, you don't know whether what you have copied is correct
> or not until you use it. So when you start using it you don't know if the
> problem is in the copied code or the code using it.
> 
> If instead of copying the code you move it and continue to use the moved
> code from the only implementation, they when you start using it with the new
> code you are sure it works and then if you have a problem you know it is not
> the moved code but the new code using it.
> 
Sure makes sense. Will move this instead of duplicating.

Regards,
Mukesh
> Christophe