Re: [PATCH net 1/2] vsock: Make accept()ed sockets use custom setsockopt()

[Stefano Garzarella]

On Tue, Dec 23, 2025 at 12:09:51PM +0100, Michal Luczaj wrote:

On 12/23/25 11:26, Stefano Garzarella wrote:

On Tue, Dec 23, 2025 at 10:15:28AM +0100, Michal Luczaj wrote:

...

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index adcba1b7bf74..c093db8fec2d 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1787,6 +1787,7 @@ static int vsock_accept(struct socket *sock, struct 
socket *newsock,
                } else {
                        newsock->state = SS_CONNECTED;
                        sock_graft(connected, newsock);
+                       set_bit(SOCK_CUSTOM_SOCKOPT, &newsock->flags);

I was a bit confused about next lines calling set_bit on
`connected->sk_socket->flags`, but after `sock_graft(connected,
newsock)` they are equivalent.

So, maybe I would move the new line before the sock_graft() call or use
`connected->sk_socket->flags` if you want to keep it after it.

...

                        if (vsock_msgzerocopy_allow(vconnected->transport))
                                set_bit(SOCK_SUPPORT_ZC,
                                        &connected->sk_socket->flags);

Hmm, isn't using both `connected->sk_socket->flags` and `newsock->flags` a
bit confusing?

Yep, for that reason I suggested to use `connected->sk_socket->flags`.

`connected->sk_socket->flags` feels unnecessary long to me.
So how about a not-so-minimal-patch to have

        newsock->state = SS_CONNECTED;
        set_bit(SOCK_CUSTOM_SOCKOPT, &newsock->flags);
        if (vsock_msgzerocopy_allow(vconnected->transport))
                set_bit(SOCK_SUPPORT_ZC, &newsock->flags);
        sock_graft(connected, newsock);

No, please, this is a fix, so let's touch less as possible.

As I mentioned before, we have 2 options IMO:
1. use `set_bit(SOCK_CUSTOM_SOCKOPT, &newsock->flags);` but move it
   before `sock_graft()`
2. use `connected->sk_socket->flags` and set it after `sock_graft()` if
   we want to be a bit more consistent

I'd go with option 2, because I like to be consistent and it's less
confusing IMHO, but I'm fine also with option 1.

Thanks,
Stefano