drm/i915: Split i915_active.mutex into an irq-safe spinlock for the rbtree

As we want to be able to run inside atomic context for retiring the
i915_active, and we are no longer allowed to abuse mutex_trylock, split
the tree management portion of i915_active.mutex into an irq-safe
spinlock.

References: a0855d24fc22d ("locking/mutex: Complain upon mutex API misuse in IRQ contexts")
References: https://bugs.freedesktop.org/show_bug.cgi?id=111626
Fixes: 274cbf20fd10 ("drm/i915: Push the i915_active.retire into a worker")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191114172535.1116-1-chris@chris-wilson.co.uk

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/selftests/i915_active.c b/drivers/gpu/drm/i915/selftests/i915_active.c
index f3fa05c78d78..60290f78750d 100644
--- a/drivers/gpu/drm/i915/selftests/i915_active.c
+++ b/drivers/gpu/drm/i915/selftests/i915_active.c
@@ -277,8 +277,8 @@ void i915_active_unlock_wait(struct i915_active *ref)
 	}
 
 	/* And wait for the retire callback */
-	mutex_lock(&ref->mutex);
-	mutex_unlock(&ref->mutex);
+	spin_lock_irq(&ref->tree_lock);
+	spin_unlock_irq(&ref->tree_lock);
 
 	/* ... which may have been on a thread instead */
 	flush_work(&ref->work);