From f21ed3407112c7236b4eaab980ca51c13b2f65dc Mon Sep 17 00:00:00 2001
From: Felix Kuehling <Felix.Kuehling@amd.com>
Date: Thu, 7 Apr 2022 22:08:03 -0400
Subject: drm/amdkfd: Asynchronously free events
Git-commit: 34d292d57973dd432e93425de33f8f120cfbdab3
Patch-mainline: v5.19-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

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.Kuehling@amd.com>
Reviewed-by: Philip Yang <Philip.Yang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 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
-- 
2.38.1