From: Alexander Bluhm <bluhm@openbsd.org>
Subject: merge sosplice_solock_pair() into solock_pair()
To: tech@openbsd.org
Date: Fri, 31 Jan 2025 13:38:31 +0100

Hi,

sosplice_solock_pair() is basically shared netlock plus solock_pair().
By making solock_pair() generic for inet and unix sockets, the
socket code needs less special locking paths.

ok?

bluhm

Index: kern/uipc_socket.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/kern/uipc_socket.c,v
diff -u -p -r1.367 uipc_socket.c
--- kern/uipc_socket.c	30 Jan 2025 14:40:50 -0000	1.367
+++ kern/uipc_socket.c	31 Jan 2025 12:12:17 -0000
@@ -537,18 +537,12 @@ soconnect(struct socket *so, struct mbuf
 int
 soconnect2(struct socket *so1, struct socket *so2)
 {
-	int persocket, error;
-
-	if ((persocket = solock_persocket(so1)))
-		solock_pair(so1, so2);
-	else
-		solock(so1);
+	int error;
 
+	solock_pair(so1, so2);
 	error = pru_connect2(so1, so2);
+	sounlock_pair(so1, so2);
 
-	if (persocket)
-		sounlock(so2);
-	sounlock(so1);
 	return (error);
 }
 
@@ -1300,38 +1294,6 @@ sorflush(struct socket *so)
 #define so_idleto	so_sp->ssp_idleto
 #define so_splicetask	so_sp->ssp_task
 
-void
-sosplice_solock_pair(struct socket *so1, struct socket *so2)
-{
-	NET_LOCK_SHARED();
-
-	if (so1 == so2)
-		rw_enter_write(&so1->so_lock);
-	else if (so1 < so2) {
-		rw_enter_write(&so1->so_lock);
-		rw_enter_write(&so2->so_lock);
-	} else {
-		rw_enter_write(&so2->so_lock);
-		rw_enter_write(&so1->so_lock);
-	}
-}
-
-void
-sosplice_sounlock_pair(struct socket *so1, struct socket *so2)
-{
-	if (so1 == so2)
-		rw_exit_write(&so1->so_lock);
-	else if (so1 < so2) {
-		rw_exit_write(&so2->so_lock);
-		rw_exit_write(&so1->so_lock);
-	} else {
-		rw_exit_write(&so1->so_lock);
-		rw_exit_write(&so2->so_lock);
-	}
-
-	NET_UNLOCK_SHARED();
-}
-
 int
 sosplice(struct socket *so, int fd, off_t max, struct timeval *tv)
 {
@@ -1397,7 +1359,7 @@ sosplice(struct socket *so, int fd, off_
 		sbunlock(&so->so_rcv);
 		goto frele;
 	}
-	sosplice_solock_pair(so, sosp);
+	solock_pair(so, sosp);
 
 	if ((so->so_options & SO_ACCEPTCONN) ||
 	    (sosp->so_options & SO_ACCEPTCONN)) {
@@ -1458,7 +1420,7 @@ sosplice(struct socket *so, int fd, off_
 	mtx_leave(&sosp->so_snd.sb_mtx);
 	mtx_leave(&so->so_rcv.sb_mtx);
 
-	sosplice_sounlock_pair(so, sosp);
+	sounlock_pair(so, sosp);
 	sbunlock(&sosp->so_snd);
 
 	if (somove(so, M_WAIT)) {
@@ -1475,7 +1437,7 @@ sosplice(struct socket *so, int fd, off_
 	return (0);
 
  release:
-	sosplice_sounlock_pair(so, sosp);
+	sounlock_pair(so, sosp);
 	sbunlock(&sosp->so_snd);
 	sbunlock(&so->so_rcv);
  frele:
Index: kern/uipc_socket2.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/kern/uipc_socket2.c,v
diff -u -p -r1.173 uipc_socket2.c
--- kern/uipc_socket2.c	31 Jan 2025 07:53:10 -0000	1.173
+++ kern/uipc_socket2.c	31 Jan 2025 12:12:17 -0000
@@ -373,16 +373,22 @@ solock_persocket(struct socket *so)
 void
 solock_pair(struct socket *so1, struct socket *so2)
 {
-	KASSERT(so1 != so2);
 	KASSERT(so1->so_type == so2->so_type);
-	KASSERT(solock_persocket(so1));
 
-	if (so1 < so2) {
-		solock(so1);
-		solock(so2);
+	switch (so1->so_proto->pr_domain->dom_family) {
+	case PF_INET:
+	case PF_INET6:
+		NET_LOCK_SHARED();
+		break;
+	}
+	if (so1 == so2) {
+		rw_enter_write(&so1->so_lock);
+	} else if (so1 < so2) {
+		rw_enter_write(&so1->so_lock);
+		rw_enter_write(&so2->so_lock);
 	} else {
-		solock(so2);
-		solock(so1);
+		rw_enter_write(&so2->so_lock);
+		rw_enter_write(&so1->so_lock);
 	}
 }
 
@@ -416,6 +422,26 @@ void
 sounlock_nonet(struct socket *so)
 {
 	rw_exit_write(&so->so_lock);
+}
+
+void
+sounlock_pair(struct socket *so1, struct socket *so2)
+{
+	if (so1 == so2)
+		rw_exit_write(&so1->so_lock);
+	else if (so1 < so2) {
+		rw_exit_write(&so2->so_lock);
+		rw_exit_write(&so1->so_lock);
+	} else {
+		rw_exit_write(&so1->so_lock);
+		rw_exit_write(&so2->so_lock);
+	}
+	switch (so1->so_proto->pr_domain->dom_family) {
+	case PF_INET:
+	case PF_INET6:
+		NET_UNLOCK_SHARED();
+		break;
+	}
 }
 
 void
Index: kern/uipc_usrreq.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/kern/uipc_usrreq.c,v
diff -u -p -r1.214 uipc_usrreq.c
--- kern/uipc_usrreq.c	25 Jan 2025 22:06:41 -0000	1.214
+++ kern/uipc_usrreq.c	31 Jan 2025 12:12:17 -0000
@@ -924,22 +924,15 @@ unp_connect(struct socket *so, struct mb
 		}
 
 		so2 = so3;
-	} else {
-		if (so2 != so)
-			solock_pair(so, so2);
-		else
-			solock(so);
-	}
+	} else
+		solock_pair(so, so2);
 
 	error = unp_connect2(so, so2);
 
-	sounlock(so);
-
 	/*
 	 * `so2' can't be PRU_ABORT'ed concurrently
 	 */
-	if (so2 != so)
-		sounlock(so2);
+	sounlock_pair(so, so2);
 put:
 	vput(vp);
 unlock:
Index: sys/socketvar.h
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/sys/socketvar.h,v
diff -u -p -r1.145 socketvar.h
--- sys/socketvar.h	31 Jan 2025 07:53:10 -0000	1.145
+++ sys/socketvar.h	31 Jan 2025 12:12:17 -0000
@@ -436,6 +436,7 @@ void	solock_pair(struct socket *, struct
 void	sounlock(struct socket *);
 void	sounlock_shared(struct socket *);
 void	sounlock_nonet(struct socket *);
+void	sounlock_pair(struct socket *, struct socket *);
 
 int	sendit(struct proc *, int, struct msghdr *, int, register_t *);
 int	recvit(struct proc *, int, struct msghdr *, caddr_t, register_t *);