From patchwork Tue Nov 26 06:55:21 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 11261539 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 D5F901390 for ; Tue, 26 Nov 2019 06:55:31 +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 BE906206BF for ; Tue, 26 Nov 2019 06:55:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BE906206BF 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 9695E89D9A; Tue, 26 Nov 2019 06:55:30 +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 47A4389D9A for ; Tue, 26 Nov 2019 06:55:29 +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 19338524-1500050 for multiple; Tue, 26 Nov 2019 06:55:27 +0000 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Tue, 26 Nov 2019 06:55:21 +0000 Message-Id: <20191126065521.2331017-1-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.24.0 MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH] drm/i915: Reduce nested prepare_remote_context() to a trylock 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" On context retiring, we may invoke the kernel_context to unpin this context. Elsewhere, we may use the kernel_context to modify this context. This currently leads to an AB-BA lock inversion, so we need to back-off from the contended lock, and repeat. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111732 Signed-off-by: Chris Wilson Reviewed-by: Tvrtko Ursulin --- drivers/gpu/drm/i915/gt/intel_context.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c index ee9d2bcd2c13..4fcb98f96da6 100644 --- a/drivers/gpu/drm/i915/gt/intel_context.c +++ b/drivers/gpu/drm/i915/gt/intel_context.c @@ -310,10 +310,8 @@ int intel_context_prepare_remote_request(struct intel_context *ce, GEM_BUG_ON(rq->hw_context == ce); if (rcu_access_pointer(rq->timeline) != tl) { /* timeline sharing! */ - err = mutex_lock_interruptible_nested(&tl->mutex, - SINGLE_DEPTH_NESTING); - if (err) - return err; + if (!mutex_trylock(&tl->mutex)) + return -EAGAIN; /* Queue this switch after current activity by this context. */ err = i915_active_fence_set(&tl->last_request, rq);