On Fri, 06 Jun 2014, Mika Kuoppala <[email protected]> wrote:
> Chris Wilson <[email protected]> writes:
>
>> 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 <[email protected]>
>> Cc: Mika Kuoppala <[email protected]>
>> Cc: [email protected]
>> ---
>
> Reviewed-by: Mika Kuoppala <[email protected]>
Pushed to -fixes, thanks for the patch and review.
BR,
Jani.
>
>> 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 a702303eab08..2974698f8f27 100644
>> --- a/drivers/gpu/drm/i915/i915_irq.c
>> +++ b/drivers/gpu/drm/i915/i915_irq.c
>> @@ -2831,10 +2831,14 @@ static int semaphore_passed(struct intel_engine_cs
>> *ring)
>> struct intel_engine_cs *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 */
>> @@ -2842,7 +2846,13 @@ static int semaphore_passed(struct intel_engine_cs
>> *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)
>> @@ -2851,7 +2861,7 @@ 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 24357c597b54..31c2aab8ad2c 100644
>> --- a/drivers/gpu/drm/i915/intel_ringbuffer.h
>> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
>> @@ -55,7 +55,7 @@ struct intel_ring_hangcheck {
>> u32 seqno;
>> int score;
>> enum intel_ring_hangcheck_action action;
>> - bool deadlock;
>> + int deadlock;
>> };
>>
>> struct intel_ringbuffer {
>> --
>> 2.0.0
> _______________________________________________
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--
Jani Nikula, Intel Open Source Technology Center
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