linux-kernel - Re: [PATCH][next] optee: make read-only array attr static const

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Message-ID: <CAHtS329G-H8vVVr==DZUAetzVNc4couN2OV3tH7qH_7YDGe8xA@mail.gmail.com>
Date: Mon, 12 Jan 2026 06:46:25 -0800
From: ryan foster <foster.ryan.r@...il.com>
To: Sumit Garg <sumit.garg@...nel.org>
Cc: Colin Ian King <coking@...dia.com>, Jens Wiklander <jens.wiklander@...aro.org>, 
	op-tee@...ts.trustedfirmware.org, kernel-janitors@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] optee: make read-only array attr static const

This looks like a micro-optimization, const makes the lookup array
explicitly immutable, and static keeps it out of the stack frame,
avoiding per-call initialization.

Is there a style preference for read only lookup arrays here, e.g.
Should these variables remain local but not static, or should they be
moved to file scope static const?

On Mon, Jan 12, 2026 at 3:26 AM Sumit Garg <sumit.garg@...nel.org> wrote:
>
> On Fri, Jan 09, 2026 at 03:44:42PM +0000, Colin Ian King wrote:
> > Don't populate the read-only array attr on the stack at run
> > time, instead make it static const.
>
> Is there any value add to do this? AFAIK, the static local variables
> aren't preffered.
>
> -Sumit
>
> >
> > Signed-off-by: Colin Ian King <coking@...dia.com>
> > ---
> >  drivers/tee/optee/rpc.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/tee/optee/rpc.c b/drivers/tee/optee/rpc.c
> > index 97fc5b14db0c..1758eb7e6e8b 100644
> > --- a/drivers/tee/optee/rpc.c
> > +++ b/drivers/tee/optee/rpc.c
> > @@ -43,7 +43,7 @@ static void handle_rpc_func_cmd_i2c_transfer(struct tee_context *ctx,
> >       struct i2c_msg msg = { };
> >       size_t i;
> >       int ret = -EOPNOTSUPP;
> > -     u8 attr[] = {
> > +     static const u8 attr[] = {
> >               TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT,
> >               TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT,
> >               TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT,
> > --
> > 2.51.0
> >
>