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drm/i915: Reorder semaphore deadlock check 

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 <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: stable@vger.kernel.org
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
This commit is contained in:
Chris Wilson 2014-06-06 10:22:29 +01:00 committed by Jani Nikula
parent eee73b4626
commit 4be173813e
2 changed files with 15 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
drivers/gpu/drm/i915/i915_irq.c
View File

@ -2847,10 +2847,14 @@ static int semaphore_passed(struct intel_engine_cs *ring)
struct intel_engine_cs *signaller; struct intel_engine_cs *signaller;
u32 seqno, ctl; u32 seqno, ctl;
ring->hangcheck.deadlock = true; ring->hangcheck.deadlock++;
signaller = semaphore_waits_for(ring, &seqno); 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; return -1;
/* cursory check for an unkickable deadlock */ /* cursory check for an unkickable deadlock */
@ -2858,7 +2862,13 @@ static int semaphore_passed(struct intel_engine_cs *ring)
if (ctl & RING_WAIT_SEMAPHORE && semaphore_passed(signaller) < 0) if (ctl & RING_WAIT_SEMAPHORE && semaphore_passed(signaller) < 0)
return -1; 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) static void semaphore_clear_deadlocks(struct drm_i915_private *dev_priv)
@ -2867,7 +2877,7 @@ static void semaphore_clear_deadlocks(struct drm_i915_private *dev_priv)
int i; int i;
for_each_ring(ring, dev_priv, i) for_each_ring(ring, dev_priv, i)
ring->hangcheck.deadlock = false; ring->hangcheck.deadlock = 0;
} }
static enum intel_ring_hangcheck_action static enum intel_ring_hangcheck_action

2
drivers/gpu/drm/i915/intel_ringbuffer.h
View File

@ -55,7 +55,7 @@ struct intel_ring_hangcheck {
u32 seqno; u32 seqno;
int score; int score;
enum intel_ring_hangcheck_action action; enum intel_ring_hangcheck_action action;
bool deadlock; int deadlock;
}; };
struct intel_ringbuffer { struct intel_ringbuffer {