linux-kernel - Re: [PATCH v4 03/30] kho: drop notifiers

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Message-ID: <CA+CK2bBS-v_djpvw3v-xumPizzmOaiPsuPpoxnSUub-LocghjQ@mail.gmail.com>
Date: Mon, 6 Oct 2025 12:17:53 -0400
From: Pasha Tatashin <pasha.tatashin@...een.com>
To: Pratyush Yadav <pratyush@...nel.org>
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Subject: Re: [PATCH v4 03/30] kho: drop notifiers

On Mon, Oct 6, 2025 at 10:30 AM Pratyush Yadav <pratyush@...nel.org> wrote:
>
> Hi Pasha,
>
> On Mon, Sep 29 2025, Pasha Tatashin wrote:
>
> > From: "Mike Rapoport (Microsoft)" <rppt@...nel.org>
> >
> > The KHO framework uses a notifier chain as the mechanism for clients to
> > participate in the finalization process. While this works for a single,
> > central state machine, it is too restrictive for kernel-internal
> > components like pstore/reserve_mem or IMA. These components need a
> > simpler, direct way to register their state for preservation (e.g.,
> > during their initcall) without being part of a complex,
> > shutdown-time notifier sequence. The notifier model forces all
> > participants into a single finalization flow and makes direct
> > preservation from an arbitrary context difficult.
> > This patch refactors the client participation model by removing the
> > notifier chain and introducing a direct API for managing FDT subtrees.
> >
> > The core kho_finalize() and kho_abort() state machine remains, but
> > clients now register their data with KHO beforehand.
> >
> > Signed-off-by: Mike Rapoport (Microsoft) <rppt@...nel.org>
> > Signed-off-by: Pasha Tatashin <pasha.tatashin@...een.com>
>
> This patch breaks build of test_kho.c (under CONFIG_TEST_KEXEC_HANDOVER):
>
>         lib/test_kho.c:49:14: error: ‘KEXEC_KHO_ABORT’ undeclared (first use in this function)
>            49 |         case KEXEC_KHO_ABORT:
>               |              ^~~~~~~~~~~~~~~
>         [...]
>         lib/test_kho.c:51:14: error: ‘KEXEC_KHO_FINALIZE’ undeclared (first use in this function)
>            51 |         case KEXEC_KHO_FINALIZE:
>               |              ^~~~~~~~~~~~~~~~~~
>         [...]
>
> I think you need to update it as well to drop notifier usage.

Yes, thank you Pratyush. I missed this change in my patch.

Pasha