From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gloria.sntech.de (gloria.sntech.de [185.11.138.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6FA5533E9 for ; Thu, 16 Mar 2023 14:22:51 +0000 (UTC) Received: from [62.91.42.93] (helo=phil.localnet) by gloria.sntech.de with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1pcoEl-0001uw-A0; Thu, 16 Mar 2023 15:05:47 +0100 From: Heiko Stuebner To: hjc@rock-chips.com, airlied@gmail.com, daniel@ffwll.ch, nathan@kernel.org, ndesaulniers@google.com, michael.riesch@wolfvision.net, s.hauer@pengutronix.de, Tom Rix Cc: dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, Tom Rix Subject: Re: [PATCH] drm/rockchip: vop2: fix uninitialized variable possible_crtcs Date: Thu, 16 Mar 2023 15:05:46 +0100 Message-ID: <8664878.T7Z3S40VBb@phil> In-Reply-To: <20230316132302.531724-1-trix@redhat.com> References: <20230316132302.531724-1-trix@redhat.com> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="iso-8859-1" Am Donnerstag, 16. M=E4rz 2023, 14:23:02 CET schrieb Tom Rix: > clang reportes this error > drivers/gpu/drm/rockchip/rockchip_drm_vop2.c:2322:8: error: > variable 'possible_crtcs' is used uninitialized whenever 'if' > condition is false [-Werror,-Wsometimes-uninitialized] > if (vp) { > ^~ > drivers/gpu/drm/rockchip/rockchip_drm_vop2.c:2336:36: note: > uninitialized use occurs here > ret =3D vop2_plane_init(vop2, win, possible_crtcs); > ^~~~~~~~~~~~~~ > drivers/gpu/drm/rockchip/rockchip_drm_vop2.c:2322:4: > note: remove the 'if' if its condition is always true > if (vp) { > ^~~~~~~~ >=20 > The else-statement changes the win->type to OVERLAY without setting the > possible_crtcs variable. Rework the block, initialize possible_crtcs to > 0 to remove the else-statement. Split the else-if-statement out to its > own if-statement so the OVERLAY check will catch when the win-type has > been changed. >=20 > Fixes: 368419a2d429 ("drm/rockchip: vop2: initialize possible_crtcs prope= rly") > Signed-off-by: Tom Rix > --- > drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) >=20 > diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/d= rm/rockchip/rockchip_drm_vop2.c > index 03ca32cd2050..fce992c3506f 100644 > --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c > +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c > @@ -2301,7 +2301,7 @@ static int vop2_create_crtcs(struct vop2 *vop2) > nvp =3D 0; > for (i =3D 0; i < vop2->registered_num_wins; i++) { > struct vop2_win *win =3D &vop2->win[i]; > - u32 possible_crtcs; > + u32 possible_crtcs =3D 0; > =20 > if (vop2->data->soc_id =3D=3D 3566) { > /* > @@ -2327,12 +2327,11 @@ static int vop2_create_crtcs(struct vop2 *vop2) > /* change the unused primary window to overlay window */ > win->type =3D DRM_PLANE_TYPE_OVERLAY; > } > - } else if (win->type =3D=3D DRM_PLANE_TYPE_OVERLAY) { > - possible_crtcs =3D (1 << nvps) - 1; > - } else { > - possible_crtcs =3D 0; > } > =20 > + if (win->type =3D=3D DRM_PLANE_TYPE_OVERLAY) > + possible_crtcs =3D (1 << nvps) - 1; > + After a long hard stare at the code in question, I think doing it this way looks like the correct one, as as you mention in the commit message the first "if" will change the win->type to OVERLAY in one case, but this then will never be added. Michael, do you agree/disagree? Thanks Heiko https://lore.kernel.org/r/20230315090158.2442771-1-michael.riesch@wolfvisio= n.net > ret =3D vop2_plane_init(vop2, win, possible_crtcs); > if (ret) { > drm_err(vop2->drm, "failed to init plane %s: %d\n", >=20