Before we mark the virtual engine as no longer inflight, flush any
ongoing signaling that may be using the ce->signal_link along the
previous breadcrumbs. On switch to a new physical engine, that link will
be inserted into the new set of breadcrumbs, causing confusion to an
ongoing iterator.
This patch undoes a last minute mistake introduced into commit
bab0557c8dca ("drm/i915/gt: Remove virtual breadcrumb before transfer"),
whereby instead of unconditionally applying the flush, it was only
applied if the request itself was going to be reused.
Fixes: bab0557c8dca ("drm/i915/gt: Remove virtual breadcrumb before transfer")
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_execlists_submission.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
index a5b442683c18..6414dbb124a7 100644
--- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
@@ -592,8 +592,6 @@ resubmit_virtual_request(struct i915_request *rq, struct virtual_engine *ve)
* ce->signal_link.
*/
i915_request_cancel_breadcrumb(rq);
- while (atomic_read(&engine->breadcrumbs->signaler_active))
- cpu_relax();
}
spin_lock_irq(&engine->active.lock);
@@ -609,6 +607,7 @@ static void kick_siblings(struct i915_request *rq, struct intel_context *ce)
{
struct virtual_engine *ve = container_of(ce, typeof(*ve), context);
struct intel_engine_cs *engine = rq->engine;
+ bool signals = !list_empty(&ce->signals);
/*
* This engine is now too busy to run this virtual request, so
@@ -622,6 +621,10 @@ static void kick_siblings(struct i915_request *rq, struct intel_context *ce)
if (READ_ONCE(ve->request))
tasklet_hi_schedule(&ve->base.execlists.tasklet);
+
+ /* Flush concurrent signal_irq_work before we reuse the link */
+ while (signals && atomic_read(&engine->breadcrumbs->signaler_active))
+ cpu_relax();
}
static inline void __execlists_schedule_out(struct i915_request *rq)
--
2.20.1
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