skmsg: Extract __tcp_bpf_recvmsg() and tcp_bpf_wait_data()

Although these two functions are only used by TCP, they are not
specific to TCP at all, both operate on skmsg and ingress_msg,
so fit in net/core/skmsg.c very well.

And we will need them for non-TCP, so rename and move them to
skmsg.c and export them to modules.

Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210331023237.41094-13-xiyou.wangcong@gmail.com

include/linux/skmsg.h

@@ -125,6 +125,10 @@ int sk_msg_zerocopy_from_iter(struct sock *sk, struct iov_iter *from,
 			      struct sk_msg *msg, u32 bytes);
 int sk_msg_memcopy_from_iter(struct sock *sk, struct iov_iter *from,
 			     struct sk_msg *msg, u32 bytes);
+int sk_msg_wait_data(struct sock *sk, struct sk_psock *psock, int flags,
+		     long timeo, int *err);
+int sk_msg_recvmsg(struct sock *sk, struct sk_psock *psock, struct msghdr *msg,
+		   int len, int flags);
 
 static inline void sk_msg_check_to_free(struct sk_msg *msg, u32 i, u32 bytes)
 {

include/net/tcp.h

@@ -2209,8 +2209,6 @@ void tcp_bpf_clone(const struct sock *sk, struct sock *newsk);
 
 int tcp_bpf_sendmsg_redir(struct sock *sk, struct sk_msg *msg, u32 bytes,
 			  int flags);
-int __tcp_bpf_recvmsg(struct sock *sk, struct sk_psock *psock,
-		      struct msghdr *msg, int len, int flags);
 #endif /* CONFIG_NET_SOCK_MSG */
 
 #if !defined(CONFIG_BPF_SYSCALL) || !defined(CONFIG_NET_SOCK_MSG)

net/core/skmsg.c

@@ -399,6 +399,104 @@ out:
 }
 EXPORT_SYMBOL_GPL(sk_msg_memcopy_from_iter);
 
+int sk_msg_wait_data(struct sock *sk, struct sk_psock *psock, int flags,
+		     long timeo, int *err)
+{
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
+	int ret = 0;
+
+	if (sk->sk_shutdown & RCV_SHUTDOWN)
+		return 1;
+
+	if (!timeo)
+		return ret;
+
+	add_wait_queue(sk_sleep(sk), &wait);
+	sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+	ret = sk_wait_event(sk, &timeo,
+			    !list_empty(&psock->ingress_msg) ||
+			    !skb_queue_empty(&sk->sk_receive_queue), &wait);
+	sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+	remove_wait_queue(sk_sleep(sk), &wait);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(sk_msg_wait_data);
+
+/* Receive sk_msg from psock->ingress_msg to @msg. */
+int sk_msg_recvmsg(struct sock *sk, struct sk_psock *psock, struct msghdr *msg,
+		   int len, int flags)
+{
+	struct iov_iter *iter = &msg->msg_iter;
+	int peek = flags & MSG_PEEK;
+	struct sk_msg *msg_rx;
+	int i, copied = 0;
+
+	msg_rx = sk_psock_peek_msg(psock);
+	while (copied != len) {
+		struct scatterlist *sge;
+
+		if (unlikely(!msg_rx))
+			break;
+
+		i = msg_rx->sg.start;
+		do {
+			struct page *page;
+			int copy;
+
+			sge = sk_msg_elem(msg_rx, i);
+			copy = sge->length;
+			page = sg_page(sge);
+			if (copied + copy > len)
+				copy = len - copied;
+			copy = copy_page_to_iter(page, sge->offset, copy, iter);
+			if (!copy)
+				return copied ? copied : -EFAULT;
+
+			copied += copy;
+			if (likely(!peek)) {
+				sge->offset += copy;
+				sge->length -= copy;
+				if (!msg_rx->skb)
+					sk_mem_uncharge(sk, copy);
+				msg_rx->sg.size -= copy;
+
+				if (!sge->length) {
+					sk_msg_iter_var_next(i);
+					if (!msg_rx->skb)
+						put_page(page);
+				}
+			} else {
+				/* Lets not optimize peek case if copy_page_to_iter
+				 * didn't copy the entire length lets just break.
+				 */
+				if (copy != sge->length)
+					return copied;
+				sk_msg_iter_var_next(i);
+			}
+
+			if (copied == len)
+				break;
+		} while (i != msg_rx->sg.end);
+
+		if (unlikely(peek)) {
+			msg_rx = sk_psock_next_msg(psock, msg_rx);
+			if (!msg_rx)
+				break;
+			continue;
+		}
+
+		msg_rx->sg.start = i;
+		if (!sge->length && msg_rx->sg.start == msg_rx->sg.end) {
+			msg_rx = sk_psock_dequeue_msg(psock);
+			kfree_sk_msg(msg_rx);
+		}
+		msg_rx = sk_psock_peek_msg(psock);
+	}
+
+	return copied;
+}
+EXPORT_SYMBOL_GPL(sk_msg_recvmsg);
+
 static struct sk_msg *sk_psock_create_ingress_msg(struct sock *sk,
 						  struct sk_buff *skb)
 {

net/ipv4/tcp_bpf.c

@@ -10,80 +10,6 @@
 #include <net/inet_common.h>
 #include <net/tls.h>
 
-int __tcp_bpf_recvmsg(struct sock *sk, struct sk_psock *psock,
-		      struct msghdr *msg, int len, int flags)
-{
-	struct iov_iter *iter = &msg->msg_iter;
-	int peek = flags & MSG_PEEK;
-	struct sk_msg *msg_rx;
-	int i, copied = 0;
-
-	msg_rx = sk_psock_peek_msg(psock);
-	while (copied != len) {
-		struct scatterlist *sge;
-
-		if (unlikely(!msg_rx))
-			break;
-
-		i = msg_rx->sg.start;
-		do {
-			struct page *page;
-			int copy;
-
-			sge = sk_msg_elem(msg_rx, i);
-			copy = sge->length;
-			page = sg_page(sge);
-			if (copied + copy > len)
-				copy = len - copied;
-			copy = copy_page_to_iter(page, sge->offset, copy, iter);
-			if (!copy)
-				return copied ? copied : -EFAULT;
-
-			copied += copy;
-			if (likely(!peek)) {
-				sge->offset += copy;
-				sge->length -= copy;
-				if (!msg_rx->skb)
-					sk_mem_uncharge(sk, copy);
-				msg_rx->sg.size -= copy;
-
-				if (!sge->length) {
-					sk_msg_iter_var_next(i);
-					if (!msg_rx->skb)
-						put_page(page);
-				}
-			} else {
-				/* Lets not optimize peek case if copy_page_to_iter
-				 * didn't copy the entire length lets just break.
-				 */
-				if (copy != sge->length)
-					return copied;
-				sk_msg_iter_var_next(i);
-			}
-
-			if (copied == len)
-				break;
-		} while (i != msg_rx->sg.end);
-
-		if (unlikely(peek)) {
-			msg_rx = sk_psock_next_msg(psock, msg_rx);
-			if (!msg_rx)
-				break;
-			continue;
-		}
-
-		msg_rx->sg.start = i;
-		if (!sge->length && msg_rx->sg.start == msg_rx->sg.end) {
-			msg_rx = sk_psock_dequeue_msg(psock);
-			kfree_sk_msg(msg_rx);
-		}
-		msg_rx = sk_psock_peek_msg(psock);
-	}
-
-	return copied;
-}
-EXPORT_SYMBOL_GPL(__tcp_bpf_recvmsg);
-
 static int bpf_tcp_ingress(struct sock *sk, struct sk_psock *psock,
 			   struct sk_msg *msg, u32 apply_bytes, int flags)
 {
@@ -237,28 +163,6 @@ static bool tcp_bpf_stream_read(const struct sock *sk)
 	return !empty;
 }
 
-static int tcp_bpf_wait_data(struct sock *sk, struct sk_psock *psock,
-			     int flags, long timeo, int *err)
-{
-	DEFINE_WAIT_FUNC(wait, woken_wake_function);
-	int ret = 0;
-
-	if (sk->sk_shutdown & RCV_SHUTDOWN)
-		return 1;
-
-	if (!timeo)
-		return ret;
-
-	add_wait_queue(sk_sleep(sk), &wait);
-	sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
-	ret = sk_wait_event(sk, &timeo,
-			    !list_empty(&psock->ingress_msg) ||
-			    !skb_queue_empty(&sk->sk_receive_queue), &wait);
-	sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
-	remove_wait_queue(sk_sleep(sk), &wait);
-	return ret;
-}
-
 static int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 		    int nonblock, int flags, int *addr_len)
 {
@@ -278,13 +182,13 @@ static int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 	}
 	lock_sock(sk);
 msg_bytes_ready:
-	copied = __tcp_bpf_recvmsg(sk, psock, msg, len, flags);
+	copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
 	if (!copied) {
 		int data, err = 0;
 		long timeo;
 
 		timeo = sock_rcvtimeo(sk, nonblock);
-		data = tcp_bpf_wait_data(sk, psock, flags, timeo, &err);
+		data = sk_msg_wait_data(sk, psock, flags, timeo, &err);
 		if (data) {
 			if (!sk_psock_queue_empty(psock))
 				goto msg_bytes_ready;

net/tls/tls_sw.c

@@ -1789,8 +1789,8 @@ int tls_sw_recvmsg(struct sock *sk,
 		skb = tls_wait_data(sk, psock, flags, timeo, &err);
 		if (!skb) {
 			if (psock) {
-				int ret = __tcp_bpf_recvmsg(sk, psock,
+				int ret = sk_msg_recvmsg(sk, psock, msg, len,
-							    msg, len, flags);
+							 flags);
 
 				if (ret > 0) {
 					decrypted += ret;