netdev - [Patch bpf-next v8 05/16] skmsg: use rcu work for destroying psock

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Date:   Tue, 30 Mar 2021 19:32:26 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     netdev@...r.kernel.org
Cc:     bpf@...r.kernel.org, duanxiongchun@...edance.com,
        wangdongdong.6@...edance.com, jiang.wang@...edance.com,
        Cong Wang <cong.wang@...edance.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jakub Sitnicki <jakub@...udflare.com>,
        Lorenz Bauer <lmb@...udflare.com>,
        John Fastabend <john.fastabend@...il.com>
Subject: [Patch bpf-next v8 05/16] skmsg: use rcu work for destroying psock

From: Cong Wang <cong.wang@...edance.com>

The RCU callback sk_psock_destroy() only queues work psock->gc,
so we can just switch to rcu work to simplify the code.

Cc: Daniel Borkmann <daniel@...earbox.net>
Cc: Jakub Sitnicki <jakub@...udflare.com>
Cc: Lorenz Bauer <lmb@...udflare.com>
Acked-by: John Fastabend <john.fastabend@...il.com>
Signed-off-by: Cong Wang <cong.wang@...edance.com>
---
 include/linux/skmsg.h |  5 +----
 net/core/skmsg.c      | 17 +++++------------
 2 files changed, 6 insertions(+), 16 deletions(-)

diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h
index 7382c4b518d7..e7aba150539d 100644
--- a/include/linux/skmsg.h
+++ b/include/linux/skmsg.h
@@ -102,10 +102,7 @@ struct sk_psock {
 	struct mutex			work_mutex;
 	struct sk_psock_work_state	work_state;
 	struct work_struct		work;
-	union {
-		struct rcu_head		rcu;
-		struct work_struct	gc;
-	};
+	struct rcu_work			rwork;
 };
 
 int sk_msg_alloc(struct sock *sk, struct sk_msg *msg, int len,
diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index 9c25020086a9..d43d43905d2c 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -666,10 +666,10 @@ void sk_psock_stop(struct sk_psock *psock, bool wait)
 
 static void sk_psock_done_strp(struct sk_psock *psock);
 
-static void sk_psock_destroy_deferred(struct work_struct *gc)
+static void sk_psock_destroy(struct work_struct *work)
 {
-	struct sk_psock *psock = container_of(gc, struct sk_psock, gc);
-
+	struct sk_psock *psock = container_of(to_rcu_work(work),
+					      struct sk_psock, rwork);
 	/* No sk_callback_lock since already detached. */
 
 	sk_psock_done_strp(psock);
@@ -688,14 +688,6 @@ static void sk_psock_destroy_deferred(struct work_struct *gc)
 	kfree(psock);
 }
 
-static void sk_psock_destroy(struct rcu_head *rcu)
-{
-	struct sk_psock *psock = container_of(rcu, struct sk_psock, rcu);
-
-	INIT_WORK(&psock->gc, sk_psock_destroy_deferred);
-	schedule_work(&psock->gc);
-}
-
 void sk_psock_drop(struct sock *sk, struct sk_psock *psock)
 {
 	sk_psock_stop(psock, false);
@@ -709,7 +701,8 @@ void sk_psock_drop(struct sock *sk, struct sk_psock *psock)
 		sk_psock_stop_verdict(sk, psock);
 	write_unlock_bh(&sk->sk_callback_lock);
 
-	call_rcu(&psock->rcu, sk_psock_destroy);
+	INIT_RCU_WORK(&psock->rwork, sk_psock_destroy);
+	queue_rcu_work(system_wq, &psock->rwork);
 }
 EXPORT_SYMBOL_GPL(sk_psock_drop);
 
-- 
2.25.1