MFC r262867

Fix PR kern/185813 "SOCK_SEQPACKET AF_UNIX sockets with asymmetrical buffers
drop packets".  It was caused by a check for the space available in a
sockbuf, but it was checking the wrong sockbuf.

sys/sys/sockbuf.h
sys/kern/uipc_sockbuf.c
	Add sbappendaddr_nospacecheck_locked(), which is just like
	sbappendaddr_locked but doesn't validate the receiving socket's space.
	Factor out common code into sbappendaddr_locked_internal().  We
	shouldn't simply make sbappendaddr_locked check the space and then call
	sbappendaddr_nospacecheck_locked, because that would cause the O(n)
	function m_length to be called twice.

sys/kern/uipc_usrreq.c
	Use sbappendaddr_nospacecheck_locked for SOCK_SEQPACKET sockets,
	because the receiving sockbuf's size limit is irrelevant.

tests/sys/kern/unix_seqpacket_test.c
	Now that 185813 is fixed, pipe_128k_8k fails intermittently due to
	185812.  Make it fail every time by adding a usleep after starting the
	writer thread and before starting the reader thread in test_pipe.  That
	gives the writer time to fill up its send buffer.  Also, clear the
	expected failure message due to 185813.  It actually said "185812", but
	that was a typo.

PR:		kern/185813

1 files changed, 10 insertions, 3 deletions

diff --git a/sys/kern/uipc_usrreq.c b/sys/kern/uipc_usrreq.c
index e1eee36..676029a 100644
--- a/sys/kern/uipc_usrreq.c
+++ b/sys/kern/uipc_usrreq.c
@@ -892,7 +892,8 @@ uipc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
 			from = &sun_noname;
 		so2 = unp2->unp_socket;
 		SOCKBUF_LOCK(&so2->so_rcv);
-		if (sbappendaddr_locked(&so2->so_rcv, from, m, control)) {
+		if (sbappendaddr_nospacecheck_locked(&so2->so_rcv, from, m,
+		    control)) {
 			sorwakeup_locked(so2);
 			m = NULL;
 			control = NULL;
@@ -977,8 +978,14 @@ uipc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
 			const struct sockaddr *from;
 
 			from = &sun_noname;
-			if (sbappendaddr_locked(&so2->so_rcv, from, m,
-			    control))
+			/*
+			 * Don't check for space available in so2->so_rcv.
+			 * Unix domain sockets only check for space in the
+			 * sending sockbuf, and that check is performed one
+			 * level up the stack.
+			 */
+			if (sbappendaddr_nospacecheck_locked(&so2->so_rcv,
+				from, m, control))
 				control = NULL;
 			break;
 			}