From 18ce18bbe96c3071d774f91fa339a9a5cf356f65 Mon Sep 17 00:00:00 2001
From: Philip Yang <Philip.Yang@amd.com>
Date: Fri, 8 Apr 2022 10:25:11 -0400
Subject: drm/amdkfd: Asynchronously free smi_client
Git-commit: 414e9f520e897818302a6b1729aa2dad8cc928ca
Patch-mainline: v6.0-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 jsc#PED-2849

The synchronize_rcu may take several ms, which noticeably slows down
applications close SMI event handle. Use call_rcu to free client->fifo
and client asynchronously and eliminate the synchronize_rcu call in the
user thread.

Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c b/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
index e5896b7a16dd..0472b56de245 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
@@ -38,6 +38,7 @@ struct kfd_smi_client {
 	uint64_t events;
 	struct kfd_dev *dev;
 	spinlock_t lock;
+	struct rcu_head rcu;
 	pid_t pid;
 	bool suser;
 };
@@ -137,6 +138,14 @@ static ssize_t kfd_smi_ev_write(struct file *filep, const char __user *user,
 	return sizeof(events);
 }
 
+static void kfd_smi_ev_client_free(struct rcu_head *p)
+{
+	struct kfd_smi_client *ev = container_of(p, struct kfd_smi_client, rcu);
+
+	kfifo_free(&ev->fifo);
+	kfree(ev);
+}
+
 static int kfd_smi_ev_release(struct inode *inode, struct file *filep)
 {
 	struct kfd_smi_client *client = filep->private_data;
@@ -146,10 +155,7 @@ static int kfd_smi_ev_release(struct inode *inode, struct file *filep)
 	list_del_rcu(&client->list);
 	spin_unlock(&dev->smi_lock);
 
-	synchronize_rcu();
-	kfifo_free(&client->fifo);
-	kfree(client);
-
+	call_rcu(&client->rcu, kfd_smi_ev_client_free);
 	return 0;
 }
 
-- 
2.38.1