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diff --git a/sys/kern/uipc_usrreq.c b/sys/kern/uipc_usrreq.c
--- a/sys/kern/uipc_usrreq.c
+++ b/sys/kern/uipc_usrreq.c
@@ -2960,6 +2960,7 @@
bcopy(path, buf, len);
buf[len] = 0;
+ so2 = NULL;
error = 0;
unp = sotounpcb(so);
@@ -2999,23 +3000,31 @@
UNP_PCB_UNLOCK(unp);
error = unp_resolve_peer(td, fd, buf, &so2);
+ if (error == 0)
+ error = unp_connect_peer(so, sotounpcb(so2), td,
+ referenced_peerp != NULL);
+
+ /*
+ * We are the ones wanting the lock, so we take it whenever a failure
+ * left us without one. A success hands ours back already held.
+ */
if (error != 0)
- goto out;
- error = unp_connect_peer(so, sotounpcb(so2), td,
- referenced_peerp != NULL);
- /* Transfer the reference; the caller releases it after unlocking. */
- if (error == 0 && referenced_peerp != NULL)
- *referenced_peerp = so2;
- else
- sorele(so2);
-out:
- if (__predict_false(error)) {
UNP_PCB_LOCK(unp);
- KASSERT((unp->unp_flags & UNP_CONNECTING) != 0,
- ("%s: unp %p has UNP_CONNECTING clear", __func__, unp));
- unp->unp_flags &= ~UNP_CONNECTING;
- UNP_PCB_UNLOCK(unp);
+ UNP_PCB_LOCK_ASSERT(unp);
+ KASSERT((unp->unp_flags & UNP_CONNECTING) != 0,
+ ("%s: unp %p has UNP_CONNECTING clear", __func__, unp));
+ unp->unp_flags &= ~UNP_CONNECTING;
+
+ if (error == 0 && referenced_peerp != NULL) {
+ /* Both PCBs stay locked, and the reference goes with them. */
+ *referenced_peerp = so2;
+ return (0);
}
+ UNP_PCB_UNLOCK(unp);
+
+ /* Only once unlocked: the last release can re-enter uipc_close(). */
+ if (so2 != NULL)
+ sorele(so2);
return (error);
}
@@ -3124,7 +3133,7 @@
/*
* Dispatch on the resolved vnode, then drop it: for the socket cases the
* returned reference keeps the peer stable, so the caller holds no vnode
- * lock across unp_connect_peer() (which matters for the return_locked
+ * lock across unp_connect_peer() (which matters for the return_peer_locked
* datagram fast path).
*
* A synthetic descriptor node -- as fdescfs fabricates for a /dev/fd/N
@@ -3194,11 +3203,14 @@
* peer socket, or the vnode lock plus unp_vp_mtxpool lock for a peer found
* via VOP_UNP_CONNECT()).
*
- * On success UNP_CONNECTING is cleared; on error the caller must clear it.
+ * On success returns with 'so's PCB lock held, so that the caller may clear
+ * UNP_CONNECTING without reacquiring it; the peer's is held as well if
+ * 'return_peer_locked', and dropped otherwise. On failure no lock is held,
+ * none having been taken.
*/
static int
unp_connect_peer(struct socket *so, struct unpcb *unp2, struct thread *td,
- bool return_locked)
+ bool return_peer_locked)
{
struct socket *so2;
struct sockaddr *sa;
@@ -3262,11 +3274,8 @@
unp_connect2(so, so2, connreq);
if (connreq)
(void)solisten_enqueue(so2, SS_ISCONNECTED);
- KASSERT((unp->unp_flags & UNP_CONNECTING) != 0,
- ("%s: unp %p has UNP_CONNECTING clear", __func__, unp));
- unp->unp_flags &= ~UNP_CONNECTING;
- if (!return_locked)
- unp_pcb_unlock_pair(unp, unp2);
+ if (!return_peer_locked && unp != unp2)
+ UNP_PCB_UNLOCK(unp2);
free(sa, M_SONAME);
return (0);
}

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