From 844c3b722855e64407b168c952faa83c291f1ffd Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 6 Jun 2014 10:22:29 +0100 Subject: [PATCH] drm/i915: Reorder semaphore deadlock check 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(-) diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index f98ba4e6e70b..e9830cd52d22 100644 --- 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_ring_buffer *ring) 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_ring_buffer *ring) 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(struct drm_i915_private *dev_priv) int i; for_each_ring(ring, dev_priv, i) - ring->hangcheck.deadlock = false; + ring->hangcheck.deadlock = 0; } static enum intel_ring_hangcheck_action diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h index 2b91c4b4d34b..4a978b97b47d 100644 --- 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 {