From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2C908CDD1AE for ; Fri, 27 Sep 2024 13:14:29 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id C3B4010E0CC; Fri, 27 Sep 2024 13:14:28 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="VtZb3mcp"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.12]) by gabe.freedesktop.org (Postfix) with ESMTPS id 1EDB310E053; Fri, 27 Sep 2024 13:14:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1727442868; x=1758978868; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version:content-transfer-encoding; bh=7Zd0nIKdA0spCjCQ15NU4V0MwrpxGgvO1Z7KesC4g1Q=; b=VtZb3mcpT+X+lyXJsRQ5qxyI3phSOn4waEwwYfqfocs35ygIa1PkE/J8 ze/VOZYO/xlnHX66TsowLch+Lh/BAyWc/hTXOqk2p+9/5W8qNdYorUcmb ja2KKNKWpVCdlzlulegmowejzfDmcxd489AsodOXMBseeKwkvfiBcqvic Rnn8HyUo8+BCLJJcyJpHCG6/6K+BxBCLxqRMRyjAhEa6bvnPrgMZPfcVg q59iEFFctlavPnO0UBh3vPL7RzzZpM9afSGseikN7fOsIbY5xwUuGf8pD ljdpj/NXRaOQIlVLf03d/B1ab9Ah+mObIKyiF7PsPOWsNnCrq/JDqBOlI g==; X-CSE-ConnectionGUID: U/PMEwyyRS+uWizDEXgE/Q== X-CSE-MsgGUID: XwiqzdsESTCKfP+n038X6A== X-IronPort-AV: E=McAfee;i="6700,10204,11207"; a="37968937" X-IronPort-AV: E=Sophos;i="6.11,158,1725346800"; d="scan'208";a="37968937" Received: from fmviesa009.fm.intel.com ([10.60.135.149]) by orvoesa104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Sep 2024 06:14:28 -0700 X-CSE-ConnectionGUID: +L79hhesTLa3X8cLSmVYog== X-CSE-MsgGUID: LToT6LpmT0y0dj/RGNN43w== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.11,158,1725346800"; d="scan'208";a="72525227" Received: from bergbenj-mobl1.ger.corp.intel.com (HELO localhost) ([10.245.246.211]) by fmviesa009-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Sep 2024 06:14:23 -0700 From: Jani Nikula To: Ville =?utf-8?B?U3lyasOkbMOk?= Cc: Alessandro Zanni , rodrigo.vivi@intel.com, joonas.lahtinen@linux.intel.com, tursulin@ursulin.net, airlied@gmail.com, simona@ffwll.ch, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, anupnewsmail@gmail.com Subject: Re: [PATCH] gpu: drm: i915: display: Avoid null values intel_plane_atomic_check_with_state In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <20240927000146.50830-1-alessandro.zanni87@gmail.com> <87tte1zewf.fsf@intel.com> Date: Fri, 27 Sep 2024 16:14:17 +0300 Message-ID: <87tte1xmqe.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" On Fri, 27 Sep 2024, Ville Syrj=C3=A4l=C3=A4 wrote: > On Fri, Sep 27, 2024 at 11:20:32AM +0300, Jani Nikula wrote: >> On Fri, 27 Sep 2024, Alessandro Zanni wro= te: >> > This fix solves multiple Smatch errors: >> > >> > drivers/gpu/drm/i915/display/intel_atomic_plane.c:660 >> > intel_plane_atomic_check_with_state() error: >> > we previously assumed 'fb' could be null (see line 648) >> > >> > drivers/gpu/drm/i915/display/intel_atomic_plane.c:664 >> > intel_plane_atomic_check_with_state() >> > error: we previously assumed 'fb' could be null (see line 659) >> > >> > drivers/gpu/drm/i915/display/intel_atomic_plane.c:671 >> > intel_plane_atomic_check_with_state() >> > error: we previously assumed 'fb' could be null (see line 663) >> > >> > We should check first if fb is not null before to access its propertie= s. >>=20 >> new_plane_state->uapi.visible && !fb should not be possible, but it's >> probably too hard for smatch to figure out. It's not exactly trivial for >> humans to figure out either. >>=20 >> I'm thinking something like below to help both. >>=20 >> Ville, thoughts? >>=20 >>=20 >> BR, >> Jani. >>=20 >>=20 >> diff --git a/drivers/gpu/drm/i915/display/intel_atomic_plane.c b/drivers= /gpu/drm/i915/display/intel_atomic_plane.c >> index 3505a5b52eb9..d9da47aed55d 100644 >> --- a/drivers/gpu/drm/i915/display/intel_atomic_plane.c >> +++ b/drivers/gpu/drm/i915/display/intel_atomic_plane.c >> @@ -629,6 +629,9 @@ int intel_plane_atomic_check_with_state(const struct= intel_crtc_state *old_crtc_ >> if (ret) >> return ret; >>=20=20 >> + if (drm_WARN_ON(display->drm, new_plane_state->uapi.visible && !fb)) >> + return -EINVAL; >> + > > We have probably 100 places that would need this. So it's going > to be extremely ugly. > > One approach I could maybe tolerate is something like > intel_plane_is_visible(plane_state)=20 > { > if (drm_WARN_ON(visible && !fb)) > return false; > > return plane_state->visible; > } > > + s/plane_state->visible/intel_plane_is_visible(plane_state)/ > > But is that going to help these obtuse tools? That does help people, which is more important. :) I think the problem is first checking if fb is NULL, and then dereferencing it anyway. visible always means fb !=3D NULL, but I forget, is the reverse true? Can we have fb !=3D NULL and !visible? I mean could we change the fb check to visible check? BR, Jani. > >> if (fb) >> new_crtc_state->enabled_planes |=3D BIT(plane->id); >>=20=20 >>=20 >>=20 >> > >> > Signed-off-by: Alessandro Zanni >> > --- >> > drivers/gpu/drm/i915/display/intel_atomic_plane.c | 6 +++--- >> > 1 file changed, 3 insertions(+), 3 deletions(-) >> > >> > diff --git a/drivers/gpu/drm/i915/display/intel_atomic_plane.c b/drive= rs/gpu/drm/i915/display/intel_atomic_plane.c >> > index e979786aa5cf..1606f79b39e6 100644 >> > --- a/drivers/gpu/drm/i915/display/intel_atomic_plane.c >> > +++ b/drivers/gpu/drm/i915/display/intel_atomic_plane.c >> > @@ -656,18 +656,18 @@ int intel_plane_atomic_check_with_state(const st= ruct intel_crtc_state *old_crtc_ >> > intel_plane_is_scaled(new_plane_state)) >> > new_crtc_state->scaled_planes |=3D BIT(plane->id); >> >=20=20 >> > - if (new_plane_state->uapi.visible && >> > + if (new_plane_state->uapi.visible && fb && >> > intel_format_info_is_yuv_semiplanar(fb->format, fb->modifier)) >> > new_crtc_state->nv12_planes |=3D BIT(plane->id); >> >=20=20 >> > - if (new_plane_state->uapi.visible && >> > + if (new_plane_state->uapi.visible && fb && >> > fb->format->format =3D=3D DRM_FORMAT_C8) >> > new_crtc_state->c8_planes |=3D BIT(plane->id); >> >=20=20 >> > if (new_plane_state->uapi.visible || old_plane_state->uapi.visible) >> > new_crtc_state->update_planes |=3D BIT(plane->id); >> >=20=20 >> > - if (new_plane_state->uapi.visible && >> > + if (new_plane_state->uapi.visible && fb && >> > intel_format_info_is_yuv_semiplanar(fb->format, fb->modifier)) { >> > new_crtc_state->data_rate_y[plane->id] =3D >> > intel_plane_data_rate(new_crtc_state, new_plane_state, 0); >>=20 >> --=20 >> Jani Nikula, Intel --=20 Jani Nikula, Intel