Subject: [PATCH bpf-next v2 2/3] tcp: Add the data length in skmsg to SIOCINQ ioctl

From: Pengcheng Yang <[email-masked]>
Date: Tue, 21 Nov 2023 19:22:04 +0800

SIOCINQ ioctl returns the number unread bytes of the receive
queue but does not include the ingress_msg queue. With the
sk_msg redirect, an application may get a value 0 if it calls
SIOCINQ ioctl before recv() to determine the readable size.

Signed-off-by: Pengcheng Yang <[email-masked]>
---
 net/ipv4/tcp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 3d3a24f79573..04da0684c397 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -267,6 +267,7 @@
 #include <linux/errqueue.h>
 #include <linux/static_key.h>
 #include <linux/btf.h>
+#include <linux/skmsg.h>
 
 #include <net/icmp.h>
 #include <net/inet_common.h>
@@ -613,7 +614,7 @@ int tcp_ioctl(struct sock *sk, int cmd, int *karg)
 			return -EINVAL;
 
 		slow = lock_sock_fast(sk);
-		answ = tcp_inq(sk);
+		answ = tcp_inq(sk) + sk_msg_queue_len(sk);
 		unlock_sock_fast(sk, slow);
 		break;
 	case SIOCATMARK:
-- 
2.38.1