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=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 B22F3C352A2 for ; Fri, 7 Feb 2020 09:14:20 +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 90BFD20726 for ; Fri, 7 Feb 2020 09:14:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 90BFD20726 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 320B16FBE4; Fri, 7 Feb 2020 09:14:20 +0000 (UTC) Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by gabe.freedesktop.org (Postfix) with ESMTPS id AF7E96FBE4 for ; Fri, 7 Feb 2020 09:14:18 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 07 Feb 2020 01:14:18 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,412,1574150400"; d="scan'208";a="379342063" Received: from gaia.fi.intel.com ([10.237.72.192]) by orsmga004.jf.intel.com with ESMTP; 07 Feb 2020 01:14:17 -0800 Received: by gaia.fi.intel.com (Postfix, from userid 1000) id 204495C0D64; Fri, 7 Feb 2020 11:13:22 +0200 (EET) From: Mika Kuoppala To: Chris Wilson , intel-gfx@lists.freedesktop.org In-Reply-To: <20200206204915.2636606-1-chris@chris-wilson.co.uk> References: <20200206204915.2636606-1-chris@chris-wilson.co.uk> Date: Fri, 07 Feb 2020 11:13:22 +0200 Message-ID: <877e0yahfx.fsf@gaia.fi.intel.com> MIME-Version: 1.0 Subject: Re: [Intel-gfx] [PATCH 1/4] drm/i915/gt: Prevent queuing retire workers on the virtual engine X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Chris Wilson writes: > Virtual engines are fleeting. They carry a reference count and may be freed > when their last request is retired. This makes them unsuitable for the > task of housing engine->retire.work so assert that it is not used. There is chicken and egg problem here that I fail to grasp. If the retire work is the mechanism which triggers the request freeing, then the order should be fine. As the engine is still there for last request. Or is the problem that it happens inside the worker which is inside the engine? -Mika > > Tvrtko tracked down an instance where we did indeed violate this rule. > In virtual_submit_request, we flush a completed request directly with > __i915_request_submit and this causes us to queue that request on the > veng's breadcrumb list and signal it. Leading us down a path where we > should not attach the retire. > > Reported-by: Tvrtko Ursulin > Fixes: dc93c9b69315 ("drm/i915/gt: Schedule request retirement when signaler idles") > Signed-off-by: Chris Wilson > Cc: Tvrtko Ursulin > --- > drivers/gpu/drm/i915/gt/intel_breadcrumbs.c | 3 +++ > drivers/gpu/drm/i915/gt/intel_gt_requests.c | 3 +++ > 2 files changed, 6 insertions(+) > > diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c > index 0ba524a414c6..cbad7fe722ce 100644 > --- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c > +++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c > @@ -136,6 +136,9 @@ static void add_retire(struct intel_breadcrumbs *b, struct intel_timeline *tl) > struct intel_engine_cs *engine = > container_of(b, struct intel_engine_cs, breadcrumbs); > > + if (unlikely(intel_engine_is_virtual(engine))) > + engine = intel_virtual_engine_get_sibling(engine, 0); > + > intel_engine_add_retire(engine, tl); > } > > diff --git a/drivers/gpu/drm/i915/gt/intel_gt_requests.c b/drivers/gpu/drm/i915/gt/intel_gt_requests.c > index 7ef1d37970f6..8a5054f21bf8 100644 > --- a/drivers/gpu/drm/i915/gt/intel_gt_requests.c > +++ b/drivers/gpu/drm/i915/gt/intel_gt_requests.c > @@ -99,6 +99,9 @@ static bool add_retire(struct intel_engine_cs *engine, > void intel_engine_add_retire(struct intel_engine_cs *engine, > struct intel_timeline *tl) > { > + /* We don't deal well with the engine disappearing beneath us */ > + GEM_BUG_ON(intel_engine_is_virtual(engine)); > + > if (add_retire(engine, tl)) > schedule_work(&engine->retire_work); > } > -- > 2.25.0 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/intel-gfx _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx