From patchwork Wed Oct 9 09:44:55 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Price X-Patchwork-Id: 11180907 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 495A613BD for ; Wed, 9 Oct 2019 09:45:05 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 3179D21A4A for ; Wed, 9 Oct 2019 09:45:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3179D21A4A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 2CCEB6E94F; Wed, 9 Oct 2019 09:45:04 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by gabe.freedesktop.org (Postfix) with ESMTP id 8CE426E94F for ; Wed, 9 Oct 2019 09:45:02 +0000 (UTC) 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 2CA8128; Wed, 9 Oct 2019 02:45:02 -0700 (PDT) Received: from e112269-lin.arm.com (unknown [10.1.196.133]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E759A3F68E; Wed, 9 Oct 2019 02:45:00 -0700 (PDT) From: Steven Price To: Daniel Vetter , David Airlie , Rob Herring , Tomeu Vizoso Subject: [PATCH v2 1/2] drm/panfrost: Handle resetting on timeout better Date: Wed, 9 Oct 2019 10:44:55 +0100 Message-Id: <20191009094456.9704-1-steven.price@arm.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org, Neil Armstrong , Alyssa Rosenzweig , dri-devel@lists.freedesktop.org, Steven Price Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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. Fixes: aa20236784ab ("drm/panfrost: Prevent concurrent resets") Tested-by: Neil Armstrong Signed-off-by: Steven Price --- v2: * Added fixes and tested-by tags * Moved cleanup of panfrost_core_dump() comment to separate patch drivers/gpu/drm/panfrost/panfrost_job.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c index a58551668d9a..21f34d44aac2 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); spin_lock_irqsave(&pfdev->js->job_lock, flags); for (i = 0; i < NUM_JOB_SLOTS; i++) {