[PATCH v5 7/11] drm/amdkfd: Asynchronously free smi_client

[Philip Yang]

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.y...@amd.com>
---
 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;
 }
 
-- 
2.35.1