linux-kernel - Re: [PATCH v7 02/22] liveupdate: luo

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Message-ID: <aSWqQWbeijvruDqf@kernel.org>
Date: Tue, 25 Nov 2025 15:08:17 +0200
From: Mike Rapoport <rppt@...nel.org>
To: Pasha Tatashin <pasha.tatashin@...een.com>
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Subject: Re: [PATCH v7 02/22] liveupdate: luo_core: integrate with KHO

On Sun, Nov 23, 2025 at 01:23:51PM -0500, Pasha Tatashin wrote:
> On Sun, Nov 23, 2025 at 9:17 AM Mike Rapoport <rppt@...nel.org> wrote:
> > > > > +static int __init liveupdate_early_init(void)
> > > > > +{
> > > > > +     int err;
> > > > > +
> > > > > +     err = luo_early_startup();
> > > > > +     if (err) {
> > > > > +             luo_global.enabled = false;
> > > > > +             luo_restore_fail("The incoming tree failed to initialize properly [%pe], disabling live update\n",
> > > > > +                              ERR_PTR(err));
> > > >
> > > > What's wrong with a plain panic()?
> > >
> > > Jason suggested using the luo_restore_fail() function instead of
> > > inserting panic() right in code somewhere in LUOv3 or earlier. It
> > > helps avoid sprinkling panics in different places, and also in case if
> > > we add the maintenance mode that we have discussed in LUOv6, we could
> > > update this function as a place where that mode would be switched on.
> >
> > I'd agree if we were to have a bunch of panic()s sprinkled in the code.
> > With a single one it's easier to parse panic() than lookup what
> > luo_restore_fail() means.
> 
> The issue is that removing luo_restore_fail() removes the only
> dependency on luo_internal.h in this patch. This would require me to
> move the introduction of that header file to a later patch in the
> series, which is difficult to handle via a simple fix-up.
> 
> Additionally, I still believe the abstraction is cleaner for future
> extensibility (like the maintenance mode), even if it currently wraps
> a single panic (which is actually a good thing, I have cleaned-up
> things substantially to have  a single point  of panic since v2).
> Therefore, it is my preference to keep it as is, unless a full series
> is needed to be re-sent.

Well, let's keep it. If we won't see new users or extensions to
luo_restore_fail() we can kill it later.
 
> Pasha

-- 
Sincerely yours,
Mike.