[PATCH 04/11] drm/i915/gt: Treat a busy timeline as 'active' while waiting

[Chris Wilson]

If we cannot claim the timeline->mutex while preparing for a wait on it,
we have to skip the timeline. In doing so, treat it as active so that
under a intel_gt_wait_for_idle() loop, we repeat the wait after
scheduling away.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/gt/intel_gt_requests.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_gt_requests.c b/drivers/gpu/drm/i915/gt/intel_gt_requests.c
index d69e78478eea..ca606b79fd5e 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_requests.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_requests.c
@@ -34,8 +34,10 @@ long intel_gt_retire_requests_timeout(struct intel_gt *gt, long timeout)
 
 	spin_lock_irqsave(&timelines->lock, flags);
 	list_for_each_entry_safe(tl, tn, &timelines->active_list, link) {
-		if (!mutex_trylock(&tl->mutex))
+		if (!mutex_trylock(&tl->mutex)) {
+			active_count++; /* report busy to caller, try again? */
 			continue;
+		}
 
 		intel_timeline_get(tl);
 		GEM_BUG_ON(!tl->active_count);
-- 
2.23.0