drm/i915/gt: Pin the rings before marking active

On eviction, we acquire the vm->mutex and then wait on the vma->active.
Therefore when binding and pinning the vma, we must follow the same
sequence, lock/pin the vma then mark it active. Otherwise, we mark the
vma as active, then wait for the vm->mutex, and meanwhile the evictor
holding the mutex waits upon us to complete our activity.

Fixes: 8ccfc20a7d56 ("drm/i915/gt: Mark ring->vma as active while pinned")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: <stable@vger.kernel.org> # v5.6+
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200706170138.8993-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
index e4aece2..52db2bd 100644 (file)
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -204,25 +204,25 @@ static int __ring_active(struct intel_ring *ring)
 {
        int err;
 
-       err = i915_active_acquire(&ring->vma->active);
+       err = intel_ring_pin(ring);
        if (err)
                return err;
 
-       err = intel_ring_pin(ring);
+       err = i915_active_acquire(&ring->vma->active);
        if (err)
-               goto err_active;
+               goto err_pin;
 
        return 0;
 
-err_active:
-       i915_active_release(&ring->vma->active);
+err_pin:
+       intel_ring_unpin(ring);
        return err;
 }
 
 static void __ring_retire(struct intel_ring *ring)
 {
-       intel_ring_unpin(ring);
        i915_active_release(&ring->vma->active);
+       intel_ring_unpin(ring);
 }
 
 __i915_active_call