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From:   Peilin Ye <yepeilin.cs@gmail.com>
To:     Eric Dumazet <edumazet@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        David Ahern <dsahern@kernel.org>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>
Cc:     Peilin Ye <peilin.ye@bytedance.com>,
        Cong Wang <cong.wang@bytedance.com>,
        Kuniyuki Iwashima <kuniyu@amazon.com>,
        Alexei Starovoitov <ast@kernel.org>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, Peilin Ye <yepeilin.cs@gmail.com>
Subject: [PATCH net-next 2/2] af_unix: Refactor unix_read_skb()
Date:   Wed, 14 Sep 2022 01:15:41 -0700
Message-Id: <6fd03b42db6b44142e517f85902e99c720277586.1663143016.git.peilin.ye@bytedance.com>
In-Reply-To: <03db9765fe1ef0f61bfc87fc68b5a95b4126aa4e.1663143016.git.peilin.ye@bytedance.com>
References: <03db9765fe1ef0f61bfc87fc68b5a95b4126aa4e.1663143016.git.peilin.ye@bytedance.com>
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From: Peilin Ye <peilin.ye@bytedance.com>

Similar to udp_read_skb(), delete the unnecessary while loop in
unix_read_skb() for readability.  Since recv_actor() cannot return a
value greater than skb->len (see sk_psock_verdict_recv()), remove the
redundant check.

Suggested-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
---
 net/unix/af_unix.c | 34 ++++++++++------------------------
 1 file changed, 10 insertions(+), 24 deletions(-)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index dea2972c8178..c955c7253d4b 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2536,32 +2536,18 @@ static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg, size_t si
 
 static int unix_read_skb(struct sock *sk, skb_read_actor_t recv_actor)
 {
-	int copied = 0;
-
-	while (1) {
-		struct unix_sock *u = unix_sk(sk);
-		struct sk_buff *skb;
-		int used, err;
-
-		mutex_lock(&u->iolock);
-		skb = skb_recv_datagram(sk, MSG_DONTWAIT, &err);
-		mutex_unlock(&u->iolock);
-		if (!skb)
-			return err;
+	struct unix_sock *u = unix_sk(sk);
+	struct sk_buff *skb;
+	int err, copied;
 
-		used = recv_actor(sk, skb);
-		if (used <= 0) {
-			if (!copied)
-				copied = used;
-			kfree_skb(skb);
-			break;
-		} else if (used <= skb->len) {
-			copied += used;
-		}
+	mutex_lock(&u->iolock);
+	skb = skb_recv_datagram(sk, MSG_DONTWAIT, &err);
+	mutex_unlock(&u->iolock);
+	if (!skb)
+		return err;
 
-		kfree_skb(skb);
-		break;
-	}
+	copied = recv_actor(sk, skb);
+	kfree_skb(skb);
 
 	return copied;
 }
-- 
2.20.1