As we may add new waiters to a request as it is being run, we need to
mark the list iteration as being safe for concurrent addition.
v2: Mika spotted that we used the same trick for signalers_list, so warn
the compiler about the lockless walk there as well.
Fixes: 32ff621fd744 ("drm/i915/gt: Allow temporary suspension of inflight requests")
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
Reviewed-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_lrc.c | 11 ++++++++---
drivers/gpu/drm/i915/i915_scheduler.c | 2 +-
2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index b350e01d86d2..ed1e4d883d47 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -1620,6 +1620,11 @@ last_active(const struct intel_engine_execlists *execlists)
&(rq__)->sched.waiters_list, \
wait_link)
+#define for_each_signaler(p__, rq__) \
+ list_for_each_entry_lockless(p__, \
+ &(rq__)->sched.signalers_list, \
+ signal_link)
+
static void defer_request(struct i915_request *rq, struct list_head * const pl)
{
LIST_HEAD(list);
@@ -2378,7 +2383,7 @@ static void __execlists_hold(struct i915_request *rq)
list_move_tail(&rq->sched.link, &rq->engine->active.hold);
i915_request_set_hold(rq);
- list_for_each_entry(p, &rq->sched.waiters_list, wait_link) {
+ for_each_waiter(p, rq) {
struct i915_request *w =
container_of(p->waiter, typeof(*w), sched);
@@ -2464,7 +2469,7 @@ static bool hold_request(const struct i915_request *rq)
* If one of our ancestors is on hold, we must also be on hold,
* otherwise we will bypass it and execute before it.
*/
- list_for_each_entry(p, &rq->sched.signalers_list, signal_link) {
+ for_each_signaler(p, rq) {
const struct i915_request *s =
container_of(p->signaler, typeof(*s), sched);
@@ -2496,7 +2501,7 @@ static void __execlists_unhold(struct i915_request *rq)
RQ_TRACE(rq, "hold release\n");
/* Also release any children on this engine that are ready */
- list_for_each_entry(p, &rq->sched.waiters_list, wait_link) {
+ for_each_waiter(p, rq) {
struct i915_request *w =
container_of(p->waiter, typeof(*w), sched);
diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
index 34b654b4e58a..e19a37a83397 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -433,7 +433,7 @@ bool __i915_sched_node_add_dependency(struct i915_sched_node *node,
node->flags |= I915_SCHED_HAS_SEMAPHORE_CHAIN;
/* All set, now publish. Beware the lockless walkers. */
- list_add(&dep->signal_link, &node->signalers_list);
+ list_add_rcu(&dep->signal_link, &node->signalers_list);
list_add_rcu(&dep->wait_link, &signal->waiters_list);
/*
--
2.25.0
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