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 X-Spam-Level: X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 31417C4361B for ; Tue, 19 Jan 2021 09:56:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E9DBB208E4 for ; Tue, 19 Jan 2021 09:56:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389077AbhASJu4 (ORCPT ); Tue, 19 Jan 2021 04:50:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46236 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387645AbhASJgt (ORCPT ); Tue, 19 Jan 2021 04:36:49 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF362C061573 for ; Tue, 19 Jan 2021 01:36:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=hvDZ+fxryuq539HgDjOUrQrHbe7h9X7Wa0ctGASWN10=; b=OgKqJ+MG9z0OBm+QeKncoVH6nk XENt9FT49QZ7pXyt0d/n9FCFplAji+NLya51furZxTzehV6KnCjtX9ae0RtvONsRPkKSt+o9omq+U FqAOa+4lAGL1GK7J5qRWeOv0HSEmmQhb3jSClOJas3LIDEHty4ow3qb7IiLIhAf7oOx6jOc8Uk42y I3J7opZCXmmgirRPi/bx4/lj0qCTKK5BzVCI49Lves81lga7JsIGfXw8D/nw+cSK1pvJrh4vNGpau 26o//HwgrWsjnJfpFQtBxmJY1RfIYA16Ra9tyMh35SuIy3WC6pxRLpjfebbYXgt3c5D6sYUQdzmUf gPDlYEsw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1l1nQN-00E7lm-FO; Tue, 19 Jan 2021 09:35:51 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 84BB7304D28; Tue, 19 Jan 2021 10:35:38 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 392A12023AA22; Tue, 19 Jan 2021 10:35:38 +0100 (CET) Date: Tue, 19 Jan 2021 10:35:38 +0100 From: Peter Zijlstra To: Christian =?iso-8859-1?Q?K=F6nig?= Cc: daniel@ffwll.ch, mingo@redhat.com, will@kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/syncobj: make lockdep complain on WAIT_FOR_SUBMIT v2 Message-ID: References: <20210118180334.43714-1-christian.koenig@amd.com> <20210118180334.43714-2-christian.koenig@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210118180334.43714-2-christian.koenig@amd.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 18, 2021 at 07:03:34PM +0100, Christian König wrote: > diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c > index 6e74e6745eca..f51458615158 100644 > --- a/drivers/gpu/drm/drm_syncobj.c > +++ b/drivers/gpu/drm/drm_syncobj.c > @@ -387,6 +387,13 @@ int drm_syncobj_find_fence(struct drm_file *file_private, > if (!syncobj) > return -ENOENT; > > + /* Waiting for userspace with locks help is illegal cause that can > + * trivial deadlock with page faults for example. Make lockdep complain > + * about it early on. > + */ Egads, the cursed comment style is spreading :/ > + if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT) > + lockdep_assert_none_held_once(); > + Should this not be part of drm_syncobj_fence_add_wait() instead? Also, do you want to sprinkle might_sleep() around ? > *fence = drm_syncobj_fence_get(syncobj); > drm_syncobj_put(syncobj); > > diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h