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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 04B09CA9ECF for ; Fri, 1 Nov 2019 14:47:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D4B4A20650 for ; Fri, 1 Nov 2019 14:46:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727463AbfKAOq6 (ORCPT ); Fri, 1 Nov 2019 10:46:58 -0400 Received: from mga07.intel.com ([134.134.136.100]:16464 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727027AbfKAOq6 (ORCPT ); Fri, 1 Nov 2019 10:46:58 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 01 Nov 2019 07:46:58 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,255,1569308400"; d="scan'208";a="351970577" Received: from cepartan-mobl3.ger.corp.intel.com (HELO [10.249.40.248]) ([10.249.40.248]) by orsmga004.jf.intel.com with ESMTP; 01 Nov 2019 07:46:55 -0700 Subject: Re: [PATCH] drm/atomic: swap_state should stall on cleanup_done To: Rob Clark , dri-devel@lists.freedesktop.org Cc: Rob Clark , Sean Paul , Maxime Ripard , Sean Paul , David Airlie , Daniel Vetter , open list References: <20191031223641.19208-1-robdclark@gmail.com> From: Maarten Lankhorst Message-ID: <7b97af56-be9b-ed2e-f692-36433a889d6e@linux.intel.com> Date: Fri, 1 Nov 2019 15:46:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20191031223641.19208-1-robdclark@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Op 31-10-2019 om 23:36 schreef Rob Clark: > From: Rob Clark > > Stalling on cleanup_done ensures that any atomic state related to a > nonblock commit no longer has dangling references to per-object state > that can be freed. > > Otherwise, if a !nonblock commit completes after a nonblock commit has > swapped state (ie. the synchronous part of the nonblock commit comes > before the !nonblock commit), but before the asynchronous part of the > nonblock commit completes, what was the new per-object state in the > nonblock commit can be freed. > > This shows up with the new self-refresh helper, as _update_avg_times() > dereferences the original old and new crtc_state. > > Fixes: d4da4e33341c ("drm: Measure Self Refresh Entry/Exit times to avoid thrashing") > Cc: Sean Paul > Signed-off-by: Rob Clark > --- > Other possibilities: > 1) maybe block later before freeing atomic state? > 2) refcount individual per-object state > > drivers/gpu/drm/drm_atomic_helper.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c > index 3ef2ac52ce94..a5d95429f91b 100644 > --- a/drivers/gpu/drm/drm_atomic_helper.c > +++ b/drivers/gpu/drm/drm_atomic_helper.c > @@ -2711,7 +2711,7 @@ int drm_atomic_helper_swap_state(struct drm_atomic_state *state, > if (!commit) > continue; > > - ret = wait_for_completion_interruptible(&commit->hw_done); > + ret = wait_for_completion_interruptible(&commit->cleanup_done); > if (ret) > return ret; > } > @@ -2722,7 +2722,7 @@ int drm_atomic_helper_swap_state(struct drm_atomic_state *state, > if (!commit) > continue; > > - ret = wait_for_completion_interruptible(&commit->hw_done); > + ret = wait_for_completion_interruptible(&commit->cleanup_done); > if (ret) > return ret; > } > @@ -2733,7 +2733,7 @@ int drm_atomic_helper_swap_state(struct drm_atomic_state *state, > if (!commit) > continue; > > - ret = wait_for_completion_interruptible(&commit->hw_done); > + ret = wait_for_completion_interruptible(&commit->cleanup_done); > if (ret) > return ret; > } Nack, hw_done means all new_crtc_state (from the old commit pov) dereferences are done. Self refresh helpers should be fixed. :)