Reduce the window of opportunity for set-wedged being called
concurrently with reset (after i915_reset() has performed the
i915_gem_unset_wedged()) by moving the set_bit(I915_WEDGED) to before we
complete the inflight requests. When i915_reset() is being blocked on a
request, such completion may allow it to start and beginning resetting
the GPU before i915_gem_set_wedged() has finished (and so before
set-wedge will have marked the device as wedged). As such,
i915_gem_init_hw() may see a wedged device even from inside
i915_reset().
References: 36703e79a982 ("drm/i915: Break modeset deadlocks on reset")
Signed-off-by: Chris Wilson <[email protected]>
Cc: Mika Kuoppala <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
---
drivers/gpu/drm/i915/i915_gem.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index c1b80cd52f9e..06f0456699af 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3205,6 +3205,9 @@ void i915_gem_set_wedged(struct drm_i915_private *i915)
intel_engine_dump(engine, &p, "%s\n", engine->name);
}
+ set_bit(I915_WEDGED, &i915->gpu_error.flags);
+ smp_mb__after_atomic();
+
/*
* First, stop submission to hw, but do not yet complete requests by
* rolling the global seqno forward (since this would complete requests
@@ -3241,7 +3244,8 @@ void i915_gem_set_wedged(struct drm_i915_private *i915)
for_each_engine(engine, i915, id) {
unsigned long flags;
- /* Mark all pending requests as complete so that any concurrent
+ /*
+ * Mark all pending requests as complete so that any concurrent
* (lockless) lookup doesn't try and wait upon the request as we
* reset it.
*/
@@ -3251,7 +3255,6 @@ void i915_gem_set_wedged(struct drm_i915_private *i915)
spin_unlock_irqrestore(&engine->timeline->lock, flags);
}
- set_bit(I915_WEDGED, &i915->gpu_error.flags);
wake_up_all(&i915->gpu_error.reset_queue);
}
--
2.16.1
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