linux-kernel - Re: [PATCH] drm/i915/gvt: fix uninitialized return in intel_gvt_update_reg

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Message-ID: <161156789392.31416.7341729779003502151@build.alporthouse.com>
Date:   Mon, 25 Jan 2021 09:44:53 +0000
From:   Chris Wilson <chris@...is-wilson.co.uk>
To:     Dan Carpenter <dan.carpenter@...cle.com>,
        Zhenyu Wang <zhenyuw@...ux.intel.com>
Cc:     Yan Zhao <yan.y.zhao@...el.com>, David Airlie <airlied@...ux.ie>,
        intel-gfx@...ts.freedesktop.org, kernel-janitors@...r.kernel.org,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        intel-gvt-dev@...ts.freedesktop.org,
        Zhi Wang <zhi.a.wang@...el.com>
Subject: Re: [PATCH] drm/i915/gvt: fix uninitialized return in intel_gvt_update_reg_whitelist()

Quoting Dan Carpenter (2021-01-25 08:48:30)
> Smatch found an uninitialized variable bug in this code:
> 
>     drivers/gpu/drm/i915/gvt/cmd_parser.c:3191 intel_gvt_update_reg_whitelist()
>     error: uninitialized symbol 'ret'.
> 
> The first thing that Smatch complains about is that "ret" isn't set if
> we don't enter the "for_each_engine(engine, &dev_priv->gt, id) {" loop.
> Presumably we always have at least one engine so that's a false
> positive.
> 
> But it's definitely a bug to not set "ret" if i915_gem_object_pin_map()
> fails.

True.
 
> Let's fix the bug and silence the false positive.
> 
> Fixes: 493f30cd086e ("drm/i915/gvt: parse init context to update cmd accessible reg whitelist")
> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Reviewed-by: Chris Wilson <chris@...is-wilson.co.uk>
-Chris