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 85ED3C369A2 for ; Tue, 8 Apr 2025 14:47:05 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E649410E6CF; Tue, 8 Apr 2025 14:47:04 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=collabora.com header.i=@collabora.com header.b="odebGuo0"; dkim-atps=neutral Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) by gabe.freedesktop.org (Postfix) with ESMTPS id 1EC2210E6CF for ; Tue, 8 Apr 2025 14:47:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1744123619; bh=3l/+LdDt9BYOa/k+vw35IDN76tFD/70Aqr4RSI5LQog=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=odebGuo09qjtBQa6bETbDReyUhxnT+390+HBJip7ET6xtXmRjJCVmCvL78bTg2c3p grjLlycqXcSlIvD7xUk/2AmN+3BUl4Lfuml2Rbl3h76I6eWBRBQ7uivBQJsr3Eig5v /4rtjC7LH+lQsKEWL2H20RYqlQzQtYdw+Oujp87ZvS3cdeD6NzKjbR5h94sBEL3SH1 vkMl3hry2MOLD292kUF2qIHhSyQTCLMFho19+PWqHIVN1TCVC9uJouCDWJmHh5OwUQ fsOmGI4DMdsK/NGfjd/cVem5sxzPnMaAc8M+1cSRkZ6gJIoTahBYT9zafygGnYBi2W S1morMARsrTPQ== Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:5cf4:84a1:2763:fe0d]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bbrezillon) by bali.collaboradmins.com (Postfix) with ESMTPSA id DBF7417E1072; Tue, 8 Apr 2025 16:46:58 +0200 (CEST) Date: Tue, 8 Apr 2025 16:46:52 +0200 From: Boris Brezillon To: =?UTF-8?B?QWRyacOhbg==?= Larumbe Cc: Steven Price , Liviu Dudau , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Sumit Semwal , Christian =?UTF-8?B?S8O2bmln?= , kernel@collabora.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org Subject: Re: [PATCH v4 4/4] drm/panthor: show device-wide list of DRM GEM objects over DebugFS Message-ID: <20250408164652.2cc26723@collabora.com> In-Reply-To: References: <20250402115432.1469703-1-adrian.larumbe@collabora.com> <20250402115432.1469703-5-adrian.larumbe@collabora.com> <20250402145804.5cf07f5e@collabora.com> <20250408154755.0d45b54b@collabora.com> Organization: Collabora X-Mailer: Claws Mail 4.3.0 (GTK 3.24.43; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Tue, 8 Apr 2025 15:38:18 +0100 Adri=C3=A1n Larumbe wrote: > On 08.04.2025 15:47, Boris Brezillon wrote: > On Tue, 8 Apr 2025 14:38:44 +0100 > Adri=C3=A1n Larumbe wrote: >=20 > > > > > diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/= drm/panthor/panthor_gem.c > > > > > index 44d027e6d664..2fc87be9b700 100644 > > > > > --- a/drivers/gpu/drm/panthor/panthor_gem.c > > > > > +++ b/drivers/gpu/drm/panthor/panthor_gem.c > > > > > @@ -2,6 +2,7 @@ > > > > > /* Copyright 2019 Linaro, Ltd, Rob Herring */ > > > > > /* Copyright 2023 Collabora ltd. */ > > > > > > > > > > +#include > > > > > #include > > > > > #include > > > > > #include > > > > > @@ -10,14 +11,65 @@ > > > > > #include > > > > > > > > > > #include "panthor_device.h" > > > > > +#include "panthor_fw.h" > > > > > #include "panthor_gem.h" > > > > > #include "panthor_mmu.h" > > > > > > > > > > +#ifdef CONFIG_DEBUG_FS > > > > > +static void panthor_gem_debugfs_bo_init(struct panthor_gem_objec= t *bo, u32 type_mask) > > > > > +{ > > > > > + INIT_LIST_HEAD(&bo->debugfs.node); =20 > > > > > > > > This should be called when the GEM object is created, otherwise the > > > > list_empty() test done in panthor_gem_debugfs_bo_rm() will only wor= k if > > > > panthor_gem_debugfs_bo_add() is called, and depending on when this > > > > happens, or whether it happens at all, the error path will do a NULL > > > > deref. =20 > > > > > > I'll be moving panthor_gem_debugfs_bo_add() back into panthor_gem_cre= ate_object() and > > > inline panthor_gem_debugfs_bo_init() into it. =20 > > > > You mean moving the panthor_gem_debugfs_bo_add() call to > > panthor_gem_create_object(), not inlining its content, right? =20 >=20 > Yes, inlining panthor_gem_debugfs_bo_init() into panthor_gem_debugfs_bo_a= dd() and moving > panthor_gem_debugfs_bo_add() into panthor_gem_create_object(). >=20 > > > > > + } else { > > > > > + bo->debugfs.creator.tgid =3D 0; > > > > > + snprintf(bo->debugfs.creator.process_name, > > > > > + sizeof(bo->debugfs.creator.process_name), > > > > > + "kernel"); > > > > > + } > > > > > + > > > > > + bo->debugfs.bo_mask =3D type_mask; =20 > > > > > > > > Why not do that directly in panthor_gem_debugfs_bo_add()? The only = bits > > > > that might be useful to do early is the INIT_LIST_HEAD(), and I thi= nk > > > > it can be inlined in panthor_gem_create_object(). =20 > > > > > > I'll be doing in this in the next revision, but because I've no acces= s to the BO > > > type mask from inside Panthor's drm_driver::gem_create_object() bindi= ng, then > > > I'll have to assign the mask right after the object has been created. > > > > > > I think this means there might be a short window after the object's b= een added to > > > the DebugFS GEMs list in which it could be shown with the kernel mask= field still > > > set to 0, but I guess that's not too important either. =20 > > > > I think it's okay, as long as you don't crash when printing partially > > initialized objects. Another solution would be to have a flag encoding > > when the obj is initialized, so you can skip objects that don't have > > this flag set yet. =20 >=20 > I think what I'll do is set the mask to a poison value, maybe 0xFF, and o= nly when > it's overwritten with a legitimate value, display the object in the Debug= FS GEMS file. Well, it's just as simple to leave it to zero at bo_add() time, and have an INITIALIZED flag that you set along the other flags in the caller of gem_shmem_create(). If you make it a poison value, you'll need to make sure it never conflicts with a valid flag combination, which might be annoying.