Use sorflush() instead of direct unp_scan(..., unp_discard) to discard

dead unix(4) sockets.

The difference in direct unp_scan() and sorflush() is the mbuf(9) chain.
For the first case it is still linked to the `so_rcv', for the second it
is not. This is required to make `sb_mtx' mutex(9) the only `so_rcv'
sockbuf protection and remove socket re-locking from the most of
uipc_*send() paths. The unlinked mbuf(9) chain doesn't require any
protection, so this allows to perform sleeping unp_discard() lockless.

Also, the mbuf(9) chain of the discarded socket still contains addresses
of file descriptors and it is much safer to unlink it before FRELE()
them. This is the reason to commit this diff standalone.

ok bluhm

diff --git a/sys/kern/uipc_socket.c b/sys/kern/uipc_socket.c
index 85032af..7b04935 100644 (file)
--- a/sys/kern/uipc_socket.c
+++ b/sys/kern/uipc_socket.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: uipc_socket.c,v 1.320 2024/02/12 22:48:27 mvs Exp $   */
+/*     $OpenBSD: uipc_socket.c,v 1.321 2024/03/22 17:34:11 mvs Exp $   */
 /*     $NetBSD: uipc_socket.c,v 1.21 1996/02/04 02:17:52 christos Exp $        */
 
 /*
@@ -65,7 +65,6 @@ void  sotask(void *);
 void   soreaper(void *);
 void   soput(void *);
 int    somove(struct socket *, int);
-void   sorflush(struct socket *);
 
 void   filt_sordetach(struct knote *kn);
 int    filt_soread(struct knote *kn, long hint);

diff --git a/sys/kern/uipc_usrreq.c b/sys/kern/uipc_usrreq.c
index b01cad4..7dc83db 100644 (file)
--- a/sys/kern/uipc_usrreq.c
+++ b/sys/kern/uipc_usrreq.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: uipc_usrreq.c,v 1.201 2024/03/17 19:47:08 mvs Exp $   */
+/*     $OpenBSD: uipc_usrreq.c,v 1.202 2024/03/22 17:34:11 mvs Exp $   */
 /*     $NetBSD: uipc_usrreq.c,v 1.18 1996/02/09 19:00:50 christos Exp $        */
 
 /*
@@ -1438,7 +1438,7 @@ unp_gc(void *arg __unused)
                                 */
                                so = unp->unp_socket;
                                solock(so);
-                               unp_scan(so->so_rcv.sb_mb, unp_discard);
+                               sorflush(so);
                                sounlock(so);
                        }
                }

diff --git a/sys/sys/socketvar.h b/sys/sys/socketvar.h
index 9ef1caf..dc34b1c 100644 (file)
--- a/sys/sys/socketvar.h
+++ b/sys/sys/socketvar.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: socketvar.h,v 1.124 2024/02/12 22:48:27 mvs Exp $     */
+/*     $OpenBSD: socketvar.h,v 1.125 2024/03/22 17:34:11 mvs Exp $     */
 /*     $NetBSD: socketvar.h,v 1.18 1996/02/09 18:25:38 christos Exp $  */
 
 /*-
@@ -394,6 +394,7 @@ int sosend(struct socket *, struct mbuf *, struct uio *,
            struct mbuf *, struct mbuf *, int);
 int    sosetopt(struct socket *, int, int, struct mbuf *);
 int    soshutdown(struct socket *, int);
+void   sorflush(struct socket *);
 void   sowakeup(struct socket *, struct sockbuf *);
 void   sorwakeup(struct socket *);
 void   sowwakeup(struct socket *);