From patchwork Tue May 1 09:49:17 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 10373483 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 15A5660384 for ; Tue, 1 May 2018 09:49:37 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 059D3287A7 for ; Tue, 1 May 2018 09:49:37 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id EB6BF28823; Tue, 1 May 2018 09:49:36 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 6338F287A7 for ; Tue, 1 May 2018 09:49:36 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id BEDA16E2D5; Tue, 1 May 2018 09:49:34 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id 465B56E2D5 for ; Tue, 1 May 2018 09:49:33 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from haswell.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 11553964-1500050 for multiple; Tue, 01 May 2018 10:49:23 +0100 Received: by haswell.alporthouse.com (sSMTP sendmail emulation); Tue, 01 May 2018 10:49:17 +0100 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Tue, 1 May 2018 10:49:17 +0100 Message-Id: <20180501094917.20881-1-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.17.0 X-Originating-IP: 78.156.65.138 X-Country: code=GB country="United Kingdom" ip=78.156.65.138 Subject: [Intel-gfx] [PATCH] drm/i915/execlists: Disable submission tasklets when rescheduling X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Virus-Scanned: ClamAV using ClamSMTP As we reschedule the requests, we do not want the submission tasklet running until we finish updating the priority chains. (We start rewriting priorities from the oldest, but the dequeue looks at the most recent in-flight, so there is a small race condition where dequeue may decide that preemption is falsely required.) Combine the tasklet kicking from adding a new request with the set-wedge protection so that we only have to adjust the preempt-counter once to achieve both goals. Reported-by: Tvrtko Ursulin Signed-off-by: Chris Wilson Cc: Tvrtko Ursulin --- drivers/gpu/drm/i915/i915_gem.c | 4 ++-- drivers/gpu/drm/i915/i915_request.c | 5 +---- 2 files changed, 3 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 438a2fc5bba0..a278e4dc5e09 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -577,10 +577,10 @@ static void __fence_set_priority(struct dma_fence *fence, rq = to_request(fence); engine = rq->engine; - rcu_read_lock(); + local_bh_disable(); /* RCU serialisation for set-wedged protection */ if (engine->schedule) engine->schedule(rq, attr); - rcu_read_unlock(); + local_bh_enable(); /* kick the tasklets if queues were reprioritised */ } static void fence_set_priority(struct dma_fence *fence, diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index 7bb613c00cc3..eb66579db823 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -1111,12 +1111,9 @@ void __i915_request_add(struct i915_request *request, bool flush_caches) * decide whether to preempt the entire chain so that it is ready to * run at the earliest possible convenience. */ - rcu_read_lock(); + local_bh_disable(); if (engine->schedule) engine->schedule(request, &request->ctx->sched); - rcu_read_unlock(); - - local_bh_disable(); i915_sw_fence_commit(&request->submit); local_bh_enable(); /* Kick the execlists tasklet if just scheduled */