Use `sb_mtx' instead of `inp_mtx' in receive path for inet sockets.

In soreceve(), we only touch `so_rcv' socket buffer, which has it's own
`sb_mtx' mutex(9) for protection. So, we can avoid solock() in this
path - it's enough to hold `sb_mtx' in soreceive() and around
corresponding sbappend*(). But not right now :)

This time we use shared netlock for some inet sockets in the soreceive()
path. To protect `so_rcv' buffer we use `inp_mtx' mutex(9) and the
pru_lock() to acquire this mutex(9) in socket layer. But the `inp_mtx'
mutex belongs to the PCB. We initialize socket before PCB, tcp(4)
sockets could exist without PCB, so use `sb_mtx' mutex(9) to protect
sockbuf stuff.

This diff mechanically replaces `inp_mtx' by `sb_mtx' in the receive
path. Only for sockets which already use `inp_mtx'. All other sockets
left as is. They will be converted later.

Since the `sb_mtx' is optional, the new SB_MTXLOCK flag introduced. If
this flag is set on `sb_flags', the `sb_mtx' mutex(9) should be taken.
New sb_mtx_lock() and sb_mtx_unlock() was introduced to hide this check.
They are temporary and will be replaced by mtx_enter() when all this
area will be converted to `sb_mtx' mutex(9).

Also, the new sbmtxassertlocked() function introduced to throw
corresponding assertion for SB_MTXLOCK marked buffers. This time only
sbappendaddr() calls it. This function is also temporary and will be
replaced by MTX_ASSERT_LOCKED() later.

ok bluhm

1 files changed, 3 insertions, 4 deletions

diff --git a/sys/netinet/ip_mroute.c b/sys/netinet/ip_mroute.c
index e318493fcd0..3e9b00ec265 100644
--- a/sys/netinet/ip_mroute.c
+++ b/sys/netinet/ip_mroute.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip_mroute.c,v 1.140 2023/12/06 09:27:17 bluhm Exp $	*/
+/*	$OpenBSD: ip_mroute.c,v 1.141 2024/02/11 18:14:26 mvs Exp $	*/
 /*	$NetBSD: ip_mroute.c,v 1.85 2004/04/26 01:31:57 matt Exp $	*/
 
 /*
@@ -1051,12 +1051,11 @@ int
 socket_send(struct socket *so, struct mbuf *mm, struct sockaddr_in *src)
 {
 	if (so != NULL) {
-		struct inpcb *inp = sotoinpcb(so);
 		int ret;
 
-		mtx_enter(&inp->inp_mtx);
+		mtx_enter(&so->so_rcv.sb_mtx);
 		ret = sbappendaddr(so, &so->so_rcv, sintosa(src), mm, NULL);
-		mtx_leave(&inp->inp_mtx);
+		mtx_leave(&so->so_rcv.sb_mtx);
 
 		if (ret != 0) {
 			sorwakeup(so);