diff mbox series

[v3,1/2] mptcp: add MSG_PEEK support

Message ID 1618565378-148180-1-git-send-email-liyonglong@chinatelecom.cn
State Superseded, archived
Delegated to: Paolo Abeni
Headers show
Series [v3,1/2] mptcp: add MSG_PEEK support | expand

Commit Message

Yonglong Li April 16, 2021, 9:29 a.m. UTC
This patch adds support for MSG_PEEK flag. Packets are not removed
from the receive_queue if MSG_PEEK set in recv() system call.

Signed-off-by: Yonglong Li <liyonglong@chinatelecom.cn>
---
 net/mptcp/protocol.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)
diff mbox series

Patch

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 16d73ec..75f4420 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1739,12 +1739,12 @@  static void mptcp_wait_data(struct sock *sk, long *timeo)
 
 static int __mptcp_recvmsg_mskq(struct mptcp_sock *msk,
 				struct msghdr *msg,
-				size_t len)
+				size_t len, int flags)
 {
-	struct sk_buff *skb;
+	struct sk_buff *skb, *tmp;
 	int copied = 0;
 
-	while ((skb = skb_peek(&msk->receive_queue)) != NULL) {
+	skb_queue_walk_safe(&msk->receive_queue, skb, tmp) {
 		u32 offset = MPTCP_SKB_CB(skb)->offset;
 		u32 data_len = skb->len - offset;
 		u32 count = min_t(size_t, len - copied, data_len);
@@ -1760,15 +1760,18 @@  static int __mptcp_recvmsg_mskq(struct mptcp_sock *msk,
 		copied += count;
 
 		if (count < data_len) {
-			MPTCP_SKB_CB(skb)->offset += count;
+			if (!(flags & MSG_PEEK))
+				MPTCP_SKB_CB(skb)->offset += count;
 			break;
 		}
 
-		/* we will bulk release the skb memory later */
-		skb->destructor = NULL;
-		msk->rmem_released += skb->truesize;
-		__skb_unlink(skb, &msk->receive_queue);
-		__kfree_skb(skb);
+		if (!(flags & MSG_PEEK)) {
+			/* we will bulk release the skb memory later */
+			skb->destructor = NULL;
+			msk->rmem_released += skb->truesize;
+			__skb_unlink(skb, &msk->receive_queue);
+			__kfree_skb(skb);
+		}
 
 		if (copied >= len)
 			break;
@@ -1945,7 +1948,7 @@  static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 	int target;
 	long timeo;
 
-	if (msg->msg_flags & ~(MSG_WAITALL | MSG_DONTWAIT))
+	if (flags & ~(MSG_PEEK | MSG_WAITALL | MSG_DONTWAIT))
 		return -EOPNOTSUPP;
 
 	mptcp_lock_sock(sk, __mptcp_splice_receive_queue(sk));
@@ -1962,7 +1965,7 @@  static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 	while (copied < len) {
 		int bytes_read;
 
-		bytes_read = __mptcp_recvmsg_mskq(msk, msg, len - copied);
+		bytes_read = __mptcp_recvmsg_mskq(msk, msg, len - copied, flags);
 		if (unlikely(bytes_read < 0)) {
 			if (!copied)
 				copied = bytes_read;
@@ -2046,7 +2049,8 @@  static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 	pr_debug("msk=%p data_ready=%d rx queue empty=%d copied=%d",
 		 msk, test_bit(MPTCP_DATA_READY, &msk->flags),
 		 skb_queue_empty_lockless(&sk->sk_receive_queue), copied);
-	mptcp_rcv_space_adjust(msk, copied);
+	if (!(flags & MSG_PEEK))
+		mptcp_rcv_space_adjust(msk, copied);
 
 	release_sock(sk);
 	return copied;