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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,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 02B8BC47404 for ; Mon, 7 Oct 2019 16:14:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D475420659 for ; Mon, 7 Oct 2019 16:14:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728718AbfJGQON (ORCPT ); Mon, 7 Oct 2019 12:14:13 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:59936 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727711AbfJGQON (ORCPT ); Mon, 7 Oct 2019 12:14:13 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: tomeu) with ESMTPSA id BF4A528F0B1 Subject: Re: [PATCH] drm/panfrost: Handle resetting on timeout better To: Neil Armstrong , Steven Price , Daniel Vetter , David Airlie , Rob Herring Cc: Alyssa Rosenzweig , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20191007125014.12595-1-steven.price@arm.com> <81430487-0aa0-8c93-653f-d7a608f3dbff@baylibre.com> From: Tomeu Vizoso Message-ID: <4fae2d1e-e399-9e2b-60dc-b8a78333845f@collabora.com> Date: Mon, 7 Oct 2019 09:14:04 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.0 MIME-Version: 1.0 In-Reply-To: <81430487-0aa0-8c93-653f-d7a608f3dbff@baylibre.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/7/19 6:09 AM, Neil Armstrong wrote: > Hi Steven, > > On 07/10/2019 14:50, Steven Price wrote: >> Panfrost uses multiple schedulers (one for each slot, so 2 in reality), >> and on a timeout has to stop all the schedulers to safely perform a >> reset. However more than one scheduler can trigger a timeout at the same >> time. This race condition results in jobs being freed while they are >> still in use. >> >> When stopping other slots use cancel_delayed_work_sync() to ensure that >> any timeout started for that slot has completed. Also use >> mutex_trylock() to obtain reset_lock. This means that only one thread >> attempts the reset, the other threads will simply complete without doing >> anything (the first thread will wait for this in the call to >> cancel_delayed_work_sync()). >> >> While we're here and since the function is already dependent on >> sched_job not being NULL, let's remove the unnecessary checks, along >> with a commented out call to panfrost_core_dump() which has never >> existed in mainline. >> > > A Fixes: tags would be welcome here so it would be backported to v5.3 > >> Signed-off-by: Steven Price >> --- >> This is a tidied up version of the patch orginally posted here: >> http://lkml.kernel.org/r/26ae2a4d-8df1-e8db-3060-41638ed63e2a%40arm.com >> >> drivers/gpu/drm/panfrost/panfrost_job.c | 17 +++++++++++------ >> 1 file changed, 11 insertions(+), 6 deletions(-) >> >> diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c >> index a58551668d9a..dcc9a7603685 100644 >> --- a/drivers/gpu/drm/panfrost/panfrost_job.c >> +++ b/drivers/gpu/drm/panfrost/panfrost_job.c >> @@ -381,13 +381,19 @@ static void panfrost_job_timedout(struct drm_sched_job *sched_job) >> job_read(pfdev, JS_TAIL_LO(js)), >> sched_job); >> >> - mutex_lock(&pfdev->reset_lock); >> + if (!mutex_trylock(&pfdev->reset_lock)) >> + return; >> >> - for (i = 0; i < NUM_JOB_SLOTS; i++) >> - drm_sched_stop(&pfdev->js->queue[i].sched, sched_job); >> + for (i = 0; i < NUM_JOB_SLOTS; i++) { >> + struct drm_gpu_scheduler *sched = &pfdev->js->queue[i].sched; >> + >> + drm_sched_stop(sched, sched_job); >> + if (js != i) >> + /* Ensure any timeouts on other slots have finished */ >> + cancel_delayed_work_sync(&sched->work_tdr); >> + } >> >> - if (sched_job) >> - drm_sched_increase_karma(sched_job); >> + drm_sched_increase_karma(sched_job); > > Indeed looks cleaner. > >> >> spin_lock_irqsave(&pfdev->js->job_lock, flags); >> for (i = 0; i < NUM_JOB_SLOTS; i++) { >> @@ -398,7 +404,6 @@ static void panfrost_job_timedout(struct drm_sched_job *sched_job) >> } >> spin_unlock_irqrestore(&pfdev->js->job_lock, flags); >> >> - /* panfrost_core_dump(pfdev); */ > > This should be cleaned in another patch ! Seems to me that this should be some kind of TODO, see etnaviv_core_dump() for the kind of things we could be doing. Maybe we can delete this line and mention this in the TODO file? Cheers, Tomeu >> >> panfrost_devfreq_record_transition(pfdev, js); >> panfrost_device_reset(pfdev); >> > > Thanks, > Testing it right now with the last change removed (doesn't apply on v5.3 with it), > results in a few hours... or minutes ! > > > Neil >