linux-kernel - Re: [Intel-gfx] [PATCH] drm/i915/mtl: avoid stringop-overflow warning

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Message-Id: <f1f8daa4-cfb9-458a-a2ca-10d654ea83fc@app.fastmail.com>
Date:   Tue, 17 Oct 2023 07:27:56 +0200
From:   "Arnd Bergmann" <arnd@...db.de>
To:     "Andi Shyti" <andi.shyti@...ux.intel.com>,
        "Arnd Bergmann" <arnd@...nel.org>
Cc:     "Jani Nikula" <jani.nikula@...ux.intel.com>,
        "Joonas Lahtinen" <joonas.lahtinen@...ux.intel.com>,
        "Rodrigo Vivi" <rodrigo.vivi@...el.com>,
        "Tvrtko Ursulin" <tvrtko.ursulin@...ux.intel.com>,
        "Dave Airlie" <airlied@...il.com>,
        "Daniel Vetter" <daniel@...ll.ch>,
        "Badal Nilawar" <badal.nilawar@...el.com>,
        "Ashutosh Dixit" <ashutosh.dixit@...el.com>,
        intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org,
        "Matt Roper" <matthew.d.roper@...el.com>
Subject: Re: [Intel-gfx] [PATCH] drm/i915/mtl: avoid stringop-overflow warning

On Tue, Oct 17, 2023, at 00:10, Andi Shyti wrote:
> Hi Arnd,
>
>>  static void rc6_res_reg_init(struct intel_rc6 *rc6)
>>  {
>> -	memset(rc6->res_reg, INVALID_MMIO_REG.reg, sizeof(rc6->res_reg));
>
> This is a complex initialization, indeed... how about just
>
>    memset(rc6->res_reg, 0, sizeof(rc6->res_reg));
>
>> +	i915_reg_t res_reg[INTEL_RC6_RES_MAX] = {
>> +		[0 ... INTEL_RC6_RES_MAX - 1] = INVALID_MMIO_REG,
>> +	};
>
> This is basically a
>
>    i915_reg_t res_reg[INTEL_RC6_RES_MAX] = { };
>
> Don't know which one is clearer.

Right, the original code went out of its way to use INVALID_MMIO_REG
instead of assuming it is zero, so I tried to preserve that for
consistency.

    Arnd