[PATCH] drm/amdkfd: Asynchronously free events

[Felix Kuehling]

The synchronize_rcu call in destroy_events can take several ms, which
noticeably slows down applications destroying many events. Use kfree_rcu
to free the event structure asynchronously and eliminate the
synchronize_rcu call in the user thread.

Signed-off-by: Felix Kuehling <felix.kuehl...@amd.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_events.c | 3 +--
 drivers/gpu/drm/amd/amdkfd/kfd_events.h | 2 ++
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_events.c 
b/drivers/gpu/drm/amd/amdkfd/kfd_events.c
index 0fef24b0b915..75847c5d5957 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_events.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_events.c
@@ -262,8 +262,7 @@ static void destroy_event(struct kfd_process *p, struct 
kfd_event *ev)
                p->signal_event_count--;
 
        idr_remove(&p->event_idr, ev->event_id);
-       synchronize_rcu();
-       kfree(ev);
+       kfree_rcu(ev, rcu);
 }
 
 static void destroy_events(struct kfd_process *p)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_events.h 
b/drivers/gpu/drm/amd/amdkfd/kfd_events.h
index 55d376f56021..1c62c8dd6460 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_events.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_events.h
@@ -70,6 +70,8 @@ struct kfd_event {
                struct kfd_hsa_memory_exception_data memory_exception_data;
                struct kfd_hsa_hw_exception_data hw_exception_data;
        };
+
+       struct rcu_head rcu; /* for asynchronous kfree_rcu */
 };
 
 #define KFD_EVENT_TIMEOUT_IMMEDIATE 0
-- 
2.32.0