On 26.09.2023 15:55, Stefano Garzarella wrote:

On Fri, Sep 22, 2023 at 08:24:18AM +0300, Arseniy Krasnov wrote:

quoted

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 new defines: 'SOL_VSOCK'
and 'VSOCK_RECVERR'.

Signed-off-by: Arseniy Krasnov <redacted>
---
Changelog:
v5(big patchset) -> v1:
 * R-b tag removed, due to added defines to 'include/uapi/linux/vsock.h'.
   Both 'SOL_VSOCK' and 'VSOCK_RECVERR' are needed by userspace, so
   they were placed to 'include/uapi/linux/vsock.h'. At the same time,
   the same define for 'SOL_VSOCK' was placed to 'include/linux/socket.h'.
   This is needed because this file contains SOL_XXX defines for different
   types of socket, so it prevents situation when another new SOL_XXX
   will use constant 287.

include/linux/socket.h     | 1 +
include/uapi/linux/vsock.h | 9 +++++++++
net/vmw_vsock/af_vsock.c   | 6 ++++++
3 files changed, 16 insertions(+)
create mode 100644 include/uapi/linux/vsock.h

diff --git a/include/linux/socket.h b/include/linux/socket.h
index 39b74d83c7c4..cfcb7e2c3813 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h

@@ -383,6 +383,7 @@ 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/include/uapi/linux/vsock.h b/include/uapi/linux/vsock.h
new file mode 100644
index 000000000000..b25c1347a3b8
--- /dev/null
+++ b/include/uapi/linux/vsock.h

We already have include/uapi/linux/vm_sockets.h

Should we include these changes there instead of creating a new header?

quoted

@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_LINUX_VSOCK_H
+#define _UAPI_LINUX_VSOCK_H
+
+#define SOL_VSOCK    287

Why we need to re-define this also here?

Reason of this re-define is that SOL_VSOCK must be exported to userspace, so
i place it to include/uapi/XXX. At the same time include/linux/socket.h contains
constants for SOL_XXX and they goes sequentially in this file (e.g. one by one,
each new value is +1 to the previous). So if I add SOL_VSOCK to include/uapi/XXX
only, it is possible that someone will add new SOL_VERY_NEW_SOCKET == 287 to
include/linux/socket.h in future. I think it is not good that two SOL_XXX will
have same value.

For example SOL_RDS and SOL_TIPS uses the same approach - there are two same defines:
one in include/uapi/ and another is in include/linux/socket.h

In that case, should we protect with some guards to avoid double
defines?

May be:

in include/linux/socket.h

#ifndef SOL_VSOCK
#define SOL_VSOCK 287
#endif

But not sure...

quoted

+
+#define VSOCK_RECVERR    1
+
+#endif /* _UAPI_LINUX_VSOCK_H */

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index d841f4de33b0..4fd11bf34bc7 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c

@@ -110,6 +110,8 @@

#include <linux/workqueue.h>
#include <net/sock.h>
#include <net/af_vsock.h>
+#include <linux/errqueue.h>
+#include <uapi/linux/vsock.h>

static int __vsock_bind(struct sock *sk, struct sockaddr_vm *addr);
static void vsock_sk_destruct(struct sock *sk);

@@ -2137,6 +2139,10 @@ 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, VSOCK_RECVERR);
+
    vsk = vsock_sk(sk);
    err = 0;

-- 
2.25.1