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Message-ID: <0daecda189cdafc89f4576b7d1da1ca219abe93d.camel@linux.ibm.com>
Subject: Re: [PATCH v2 2/7] powerpc/secvar: WARN_ON_ONCE() if multiple
 secvar ops are set
From:   Andrew Donnellan <ajd@linux.ibm.com>
To:     Russell Currey <ruscur@russell.cc>, linuxppc-dev@lists.ozlabs.org
Cc:     gregkh@linuxfoundation.org, gcwilson@linux.ibm.com,
        linux-kernel@vger.kernel.org, nayna@linux.ibm.com,
        zohar@linux.ibm.com, mpe@ellerman.id.au
Date:   Wed, 04 Jan 2023 18:10:28 +1100
In-Reply-To: <20221230042014.154483-3-ruscur@russell.cc>
References: <20221230042014.154483-1-ruscur@russell.cc>
         <20221230042014.154483-3-ruscur@russell.cc>
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On Fri, 2022-12-30 at 15:20 +1100, Russell Currey wrote:
> The secvar code only supports one consumer at a time.
>=20
> Multiple consumers aren't possible at this point in time, but we'd
> want
> it to be obvious if it ever could happen.
>=20
> Signed-off-by: Russell Currey <ruscur@russell.cc>

This seems sensible - there aren't any cases where set_secvar_ops()
should be called twice.

> ---
> =C2=A0arch/powerpc/kernel/secvar-ops.c | 4 +++-
> =C2=A01 file changed, 3 insertions(+), 1 deletion(-)
>=20
> diff --git a/arch/powerpc/kernel/secvar-ops.c
> b/arch/powerpc/kernel/secvar-ops.c
> index 6a29777d6a2d..aa1b2adc2710 100644
> --- a/arch/powerpc/kernel/secvar-ops.c
> +++ b/arch/powerpc/kernel/secvar-ops.c
> @@ -8,10 +8,12 @@
> =C2=A0
> =C2=A0#include <linux/cache.h>
> =C2=A0#include <asm/secvar.h>
> +#include <asm/bug.h>
> =C2=A0
> -const struct secvar_operations *secvar_ops __ro_after_init;
> +const struct secvar_operations *secvar_ops __ro_after_init =3D NULL;

I think this is implicitly NULL, but it's fine to make it explicit.

Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>

> =C2=A0
> =C2=A0void set_secvar_ops(const struct secvar_operations *ops)
> =C2=A0{
> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0WARN_ON_ONCE(secvar_ops);
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0secvar_ops =3D ops;
> =C2=A0}

--=20
Andrew Donnellan    OzLabs, ADL Canberra
ajd@linux.ibm.com   IBM Australia Limited