From patchwork Tue Dec 3 11:53:39 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 11271071 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 B7B7B112B for ; Tue, 3 Dec 2019 11:53:47 +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 A020D206EC for ; Tue, 3 Dec 2019 11:53:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A020D206EC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=chris-wilson.co.uk 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 D86896E489; Tue, 3 Dec 2019 11:53:46 +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 D761D6E489 for ; Tue, 3 Dec 2019 11:53:45 +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 19440776-1500050 for multiple; Tue, 03 Dec 2019 11:53:38 +0000 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Tue, 3 Dec 2019 11:53:39 +0000 Message-Id: <20191203115339.2943374-2-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191203115339.2943374-1-chris@chris-wilson.co.uk> References: <20191203115339.2943374-1-chris@chris-wilson.co.uk> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 2/2] drm/i915/execlists: Skip nested spinlock for validating pending 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: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Only along the submission path can we guarantee that the locked request is indeed from a foreign engine, and so the nesting of engine/rq is permissible. On the submission tasklet (process_csb()), we may find ourselves competing with the normal nesting of rq/engine, invalidating our nesting. As we only use the spinlock for debug purposes, skip the debug if we cannot acquire the spinlock for safe validation - catching 99% of the bugs is better than causing a hard lockup. Signed-off-by: Chris Wilson Reviewed-by: Tvrtko Ursulin --- drivers/gpu/drm/i915/gt/intel_lrc.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c index 37ab9742abe7..b411e4ce6771 100644 --- a/drivers/gpu/drm/i915/gt/intel_lrc.c +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c @@ -1300,7 +1300,6 @@ assert_pending_valid(const struct intel_engine_execlists *execlists, } for (port = execlists->pending; (rq = *port); port++) { - unsigned long flags; bool ok = true; GEM_BUG_ON(!kref_read(&rq->fence.refcount)); @@ -1315,8 +1314,8 @@ assert_pending_valid(const struct intel_engine_execlists *execlists, ce = rq->hw_context; /* Hold tightly onto the lock to prevent concurrent retires! */ - spin_lock_irqsave_nested(&rq->lock, flags, - SINGLE_DEPTH_NESTING); + if (!spin_trylock(&rq->lock)) + continue; if (i915_request_completed(rq)) goto unlock; @@ -1347,7 +1346,7 @@ assert_pending_valid(const struct intel_engine_execlists *execlists, } unlock: - spin_unlock_irqrestore(&rq->lock, flags); + spin_unlock(&rq->lock); if (!ok) return false; }