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.
v2: Generalise and cancel all remaining ce->signals
Fixes: bab0557c8dca ("drm/i915/gt: Remove virtual breadcrumb before transfer")
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Reviewed-by: Andi Shyti <andi.sh...@intel.com>
---
drivers/gpu/drm/i915/gt/intel_breadcrumbs.c | 33 +++++++++++++++++++
drivers/gpu/drm/i915/gt/intel_breadcrumbs.h | 4 +++
.../drm/i915/gt/intel_execlists_submission.c | 25 ++++++--------
3 files changed, 47 insertions(+), 15 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
index 2eabb9ab5d47..7137b6f24f55 100644
--- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
@@ -472,6 +472,39 @@ void i915_request_cancel_breadcrumb(struct i915_request
*rq)
i915_request_put(rq);
}
+void intel_context_remove_breadcrumbs(struct intel_context *ce,
+ struct intel_breadcrumbs *b)
+{
+ struct i915_request *rq, *rn;
+ bool release = false;
+ unsigned long flags;
+
+ spin_lock_irqsave(&ce->signal_lock, flags);
+
+ if (list_empty(&ce->signals))
+ goto unlock;
+
+ list_for_each_entry_safe(rq, rn, &ce->signals, signal_link) {
+ GEM_BUG_ON(!__i915_request_is_complete(rq));
+ if (!test_and_clear_bit(I915_FENCE_FLAG_SIGNAL,
+ &rq->fence.flags))
+ continue;
+
+ list_del_rcu(&rq->signal_link);
+ irq_signal_request(rq, b);
+ i915_request_put(rq);
+ }
+ release = remove_signaling_context(b, ce);
+
+unlock:
+ spin_unlock_irqrestore(&ce->signal_lock, flags);
+ if (release)
+ intel_context_put(ce);
+
+ while (atomic_read(&b->signaler_active))
+ cpu_relax();
+}
+
static void print_signals(struct intel_breadcrumbs *b, struct drm_printer *p)
{
struct intel_context *ce;
diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.h
b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.h
index 75cc9cff3ae3..3ce5ce270b04 100644
--- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.h
+++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.h
@@ -6,6 +6,7 @@
#ifndef __INTEL_BREADCRUMBS__
#define __INTEL_BREADCRUMBS__
+#include <linux/atomic.h>
#include <linux/irq_work.h>
#include "intel_engine_types.h"
@@ -44,4 +45,7 @@ void intel_engine_print_breadcrumbs(struct intel_engine_cs
*engine,
bool i915_request_enable_breadcrumb(struct i915_request *request);
void i915_request_cancel_breadcrumb(struct i915_request *request);
+void intel_context_remove_breadcrumbs(struct intel_context *ce,
+ struct intel_breadcrumbs *b);
+
#endif /* __INTEL_BREADCRUMBS__ */
diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
index 2f8e10450f7e..eb69eef9d7db 100644
--- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
@@ -581,21 +581,6 @@ resubmit_virtual_request(struct i915_request *rq, struct
virtual_engine *ve)
{
struct intel_engine_cs *engine = rq->engine;
- /* Flush concurrent rcu iterators in signal_irq_work */
- if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &rq->fence.flags)) {
- /*
- * After this point, the rq may be transferred to a new
- * sibling, so before we clear ce->inflight make sure that
- * the context has been removed from the b->signalers and
- * furthermore we need to make sure that the concurrent
- * iterator in signal_irq_work is no longer following
- * ce->signal_link.
- */
- i915_request_cancel_breadcrumb(rq);
- while (atomic_read(&engine->breadcrumbs->signaler_active))
- cpu_relax();
- }
-
spin_lock_irq(&engine->active.lock);
clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
@@ -610,6 +595,16 @@ 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;
+ /*
+ * After this point, the rq may be transferred to a new sibling, so
+ * before we clear ce->inflight make sure that the context has been
+ * removed from the b->signalers and furthermore we need to make sure
+ * that the concurrent iterator in signal_irq_work is no longer
+ * following ce->signal_link.
+ */
+ if (!list_empty(&ce->signals))
+ intel_context_remove_breadcrumbs(ce, engine->breadcrumbs);
+
/*
* This engine is now too busy to run this virtual request, so
* see if we can find an alternative engine for it to execute on.
--
2.20.1
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