Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756182AbaGHA66 (ORCPT ); Mon, 7 Jul 2014 20:58:58 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:55403 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751676AbaGGXyI (ORCPT ); Mon, 7 Jul 2014 19:54:08 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Chris Wilson , Mika Kuoppala , Mika Kuoppala , Jani Nikula Subject: [PATCH 3.15 040/122] drm/i915: Reorder semaphore deadlock check Date: Mon, 7 Jul 2014 16:56:42 -0700 Message-Id: <20140707235735.448844403@linuxfoundation.org> X-Mailer: git-send-email 2.0.0.254.g50f84e3 In-Reply-To: <20140707235734.234226883@linuxfoundation.org> References: <20140707235734.234226883@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chris Wilson commit 4be173813e57c7298103a83155c2391b5b167b4c upstream. If a semaphore is waiting on another ring, which in turn happens to be waiting on the first ring, but that second semaphore has been signalled, we will be able to kick the second ring and so can treat the first ring as a valid WAIT and not as HUNG. v2: Be paranoid and cap the potential recursion depth whilst visiting the semaphore signallers. (Mika) References: https://bugs.freedesktop.org/show_bug.cgi?id=54226 References: https://bugs.freedesktop.org/show_bug.cgi?id=75502 Signed-off-by: Chris Wilson Cc: Mika Kuoppala Reviewed-by: Mika Kuoppala Signed-off-by: Jani Nikula Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/i915/i915_irq.c | 18 ++++++++++++++---- drivers/gpu/drm/i915/intel_ringbuffer.h | 2 +- 2 files changed, 15 insertions(+), 5 deletions(-) --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -2561,10 +2561,14 @@ static int semaphore_passed(struct intel struct intel_ring_buffer *signaller; u32 seqno, ctl; - ring->hangcheck.deadlock = true; + ring->hangcheck.deadlock++; signaller = semaphore_waits_for(ring, &seqno); - if (signaller == NULL || signaller->hangcheck.deadlock) + if (signaller == NULL) + return -1; + + /* Prevent pathological recursion due to driver bugs */ + if (signaller->hangcheck.deadlock >= I915_NUM_RINGS) return -1; /* cursory check for an unkickable deadlock */ @@ -2572,7 +2576,13 @@ static int semaphore_passed(struct intel if (ctl & RING_WAIT_SEMAPHORE && semaphore_passed(signaller) < 0) return -1; - return i915_seqno_passed(signaller->get_seqno(signaller, false), seqno); + if (i915_seqno_passed(signaller->get_seqno(signaller, false), seqno)) + return 1; + + if (signaller->hangcheck.deadlock) + return -1; + + return 0; } static void semaphore_clear_deadlocks(struct drm_i915_private *dev_priv) @@ -2581,7 +2591,7 @@ static void semaphore_clear_deadlocks(st int i; for_each_ring(ring, dev_priv, i) - ring->hangcheck.deadlock = false; + ring->hangcheck.deadlock = 0; } static enum intel_ring_hangcheck_action --- a/drivers/gpu/drm/i915/intel_ringbuffer.h +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h @@ -51,7 +51,7 @@ struct intel_ring_hangcheck { u32 seqno; int score; enum intel_ring_hangcheck_action action; - bool deadlock; + int deadlock; }; struct intel_ring_buffer { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/