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, URIBL_BLOCKED,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 48E23C4360C for ; Thu, 26 Sep 2019 12:30:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1EDAA207FF for ; Thu, 26 Sep 2019 12:30:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726414AbfIZMai (ORCPT ); Thu, 26 Sep 2019 08:30:38 -0400 Received: from foss.arm.com ([217.140.110.172]:48310 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725787AbfIZMai (ORCPT ); Thu, 26 Sep 2019 08:30:38 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 323F7142F; Thu, 26 Sep 2019 05:30:37 -0700 (PDT) Received: from [10.1.196.133] (e112269-lin.cambridge.arm.com [10.1.196.133]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2C2DC3F67D; Thu, 26 Sep 2019 05:30:36 -0700 (PDT) Subject: Re: [PATCH v2] drm: Don't free jobs in wait_event_interruptible() To: Daniel Vetter , David Airlie , =?UTF-8?Q?Christian_K=c3=b6nig?= Cc: Sharat Masetty , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Nayan Deshmukh , Alex Deucher References: <20190926095458.50020-1-steven.price@arm.com> From: Steven Price Message-ID: Date: Thu, 26 Sep 2019 13:30:34 +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: <20190926095458.50020-1-steven.price@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 26/09/2019 10:54, Steven Price wrote: > drm_sched_cleanup_jobs() attempts to free finished jobs, however because > it is called as the condition of wait_event_interruptible() it must not > sleep. Unfortuantly some free callbacks (notibly for Panfrost) do sleep. > > Instead let's rename drm_sched_cleanup_jobs() to > drm_sched_get_cleanup_job() and simply return a job for processing if > there is one. The caller can then call the free_job() callback outside > the wait_event_interruptible() where sleeping is possible before > re-checking and returning to sleep if necessary. > > Signed-off-by: Steven Price > --- > > Changes from v1: > * Move list_first_entry_or_null() within the lock Or rather that was my intention - but apparently I fat fingered and didn't actually include this change. Sorry - v3 on it's way! Steve > > drivers/gpu/drm/scheduler/sched_main.c | 44 ++++++++++++++------------ > 1 file changed, 24 insertions(+), 20 deletions(-) > > diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c > index 9a0ee74d82dc..0ed4aaa4e6d1 100644 > --- a/drivers/gpu/drm/scheduler/sched_main.c > +++ b/drivers/gpu/drm/scheduler/sched_main.c > @@ -622,43 +622,41 @@ static void drm_sched_process_job(struct dma_fence *f, struct dma_fence_cb *cb) > } > > /** > - * drm_sched_cleanup_jobs - destroy finished jobs > + * drm_sched_get_cleanup_job - fetch the next finished job to be destroyed > * > * @sched: scheduler instance > * > - * Remove all finished jobs from the mirror list and destroy them. > + * Returns the next finished job from the mirror list (if there is one) > + * ready for it to be destroyed. > */ > -static void drm_sched_cleanup_jobs(struct drm_gpu_scheduler *sched) > +static struct drm_sched_job * > +drm_sched_get_cleanup_job(struct drm_gpu_scheduler *sched) > { > + struct drm_sched_job *job = NULL; > unsigned long flags; > > /* Don't destroy jobs while the timeout worker is running */ > if (sched->timeout != MAX_SCHEDULE_TIMEOUT && > !cancel_delayed_work(&sched->work_tdr)) > - return; > - > - > - while (!list_empty(&sched->ring_mirror_list)) { > - struct drm_sched_job *job; > + return NULL; > > - job = list_first_entry(&sched->ring_mirror_list, > + job = list_first_entry_or_null(&sched->ring_mirror_list, > struct drm_sched_job, node); > - if (!dma_fence_is_signaled(&job->s_fence->finished)) > - break; > > - spin_lock_irqsave(&sched->job_list_lock, flags); > + spin_lock_irqsave(&sched->job_list_lock, flags); > + > + if (job && dma_fence_is_signaled(&job->s_fence->finished)) { > /* remove job from ring_mirror_list */ > list_del_init(&job->node); > - spin_unlock_irqrestore(&sched->job_list_lock, flags); > - > - sched->ops->free_job(job); > + } else { > + job = NULL; > + /* queue timeout for next job */ > + drm_sched_start_timeout(sched); > } > > - /* queue timeout for next job */ > - spin_lock_irqsave(&sched->job_list_lock, flags); > - drm_sched_start_timeout(sched); > spin_unlock_irqrestore(&sched->job_list_lock, flags); > > + return job; > } > > /** > @@ -698,12 +696,18 @@ static int drm_sched_main(void *param) > struct drm_sched_fence *s_fence; > struct drm_sched_job *sched_job; > struct dma_fence *fence; > + struct drm_sched_job *cleanup_job = NULL; > > wait_event_interruptible(sched->wake_up_worker, > - (drm_sched_cleanup_jobs(sched), > + (cleanup_job = drm_sched_get_cleanup_job(sched)) || > (!drm_sched_blocked(sched) && > (entity = drm_sched_select_entity(sched))) || > - kthread_should_stop())); > + kthread_should_stop()); > + > + while (cleanup_job) { > + sched->ops->free_job(cleanup_job); > + cleanup_job = drm_sched_get_cleanup_job(sched); > + } > > if (!entity) > continue; >