[RFC PATCH v5 07/17] vsock: read from socket's error queue

[Arseniy Krasnov <AVKrasnov@sberdevices.ru>]

This adds handling of MSG_ERRQUEUE input flag in receive call. This flag
is used to read socket's error queue instead of data queue. Possible
scenario of error queue usage is receiving completions for transmission
with MSG_ZEROCOPY flag. This patch also adds 'SOL_VSOCK' define.

Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
---
 Changelog:
 v4 -> v5:
  * Update commit message by adding sentence that 'SOL_VSOCK' is also
    added.

 include/linux/socket.h   | 1 +
 net/vmw_vsock/af_vsock.c | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/include/linux/socket.h b/include/linux/socket.h
index bd1cc3238851..d79efd026880 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -382,6 +382,7 @@ struct ucred {
 #define SOL_MPTCP	284
 #define SOL_MCTP	285
 #define SOL_SMC		286
+#define SOL_VSOCK	287
 
 /* IPX options */
 #define IPX_TYPE	1
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 45fd20c4ed50..07803d9fbf6d 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -110,6 +110,7 @@
 #include <linux/workqueue.h>
 #include <net/sock.h>
 #include <net/af_vsock.h>
+#include <linux/errqueue.h>
 
 static int __vsock_bind(struct sock *sk, struct sockaddr_vm *addr);
 static void vsock_sk_destruct(struct sock *sk);
@@ -2135,6 +2136,10 @@ vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 	int err;
 
 	sk = sock->sk;
+
+	if (unlikely(flags & MSG_ERRQUEUE))
+		return sock_recv_errqueue(sk, msg, len, SOL_VSOCK, 0);
+
 	vsk = vsock_sk(sk);
 	err = 0;
 
-- 
2.25.1