From: Vitaliy Makkoveev <mvs@openbsd.org>
Subject: sosplice(): remove socket state and options checks in unsplice path
To: Alexander Bluhm <bluhm@openbsd.org>, tech@openbsd.org
Date: Thu, 2 Jan 2025 12:18:25 +0300

In ancient times the unsplicing path was the part of splicing, so it
follows these checks too. While doing sosplice() reorder, I left them to
keep API as is, but now I want to remove these checks. Socket splicing
is about socket buffers which have their own locks, so socket locks
are not required for splicing and unsplicing, moreover socket splicing
relays on sblock() on so_rcv, not the solock(). I want to move solock()
down to sonsplice() and keep it only around optional sor{r,w}akeup(),
so these useless checks before sounsplice() brings nothing, but requires
to take solock() and stop packet processing.

I performed kern/sosplice tests without any issues, so I suspect this
API change will be transparent.

Index: sys/kern/uipc_socket.c
===================================================================
RCS file: /cvs/src/sys/kern/uipc_socket.c,v
diff -u -p -r1.352 uipc_socket.c
--- sys/kern/uipc_socket.c	31 Dec 2024 12:19:46 -0000	1.352
+++ sys/kern/uipc_socket.c	2 Jan 2025 09:04:18 -0000
@@ -1338,22 +1338,11 @@ sosplice(struct socket *so, int fd, off_
 		if ((error = sblock(&so->so_rcv, SBL_WAIT)) != 0)
 			return (error);
 		solock(so);
-		if (so->so_options & SO_ACCEPTCONN) {
-			error = EOPNOTSUPP;
-			goto out;
-		}
-		if ((so->so_state & (SS_ISCONNECTED|SS_ISCONNECTING)) == 0 &&
-		    (so->so_proto->pr_flags & PR_CONNREQUIRED)) {
-			error = ENOTCONN;
-			goto out;
-		}
-
 		if (so->so_sp && so->so_sp->ssp_socket)
 			sounsplice(so, so->so_sp->ssp_socket, 0);
- out:
 		sounlock(so);
 		sbunlock(&so->so_rcv);
-		return (error);
+		return (0);
 	}
 
 	if (sosplice_taskq == NULL) {