Author: markj Date: Tue Sep 15 19:22:37 2020 New Revision: 365762 URL: https://svnweb.freebsd.org/changeset/base/365762
Log: Simplify unp_disconnect() callers. In all cases, PCBs are unlocked after unp_disconnect() returns. Since unp_disconnect() may release the last PCB reference, callers may have to bump the refcount before the call just so that they can release them again. Change unp_disconnect() to release PCB locks as well as connection references; this lets us remove several refcount manipulations. Tighten assertions. Tested by: pho Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D26297 Modified: head/sys/kern/uipc_usrreq.c Modified: head/sys/kern/uipc_usrreq.c ============================================================================== --- head/sys/kern/uipc_usrreq.c Tue Sep 15 19:22:16 2020 (r365761) +++ head/sys/kern/uipc_usrreq.c Tue Sep 15 19:22:37 2020 (r365762) @@ -335,6 +335,15 @@ unp_pcb_rele(struct unpcb *unp) } static void +unp_pcb_rele_notlast(struct unpcb *unp) +{ + bool ret __unused; + + ret = refcount_release(&unp->unp_refcount); + KASSERT(!ret, ("%s: unpcb %p has no references", __func__, unp)); +} + +static void unp_pcb_lock_pair(struct unpcb *unp, struct unpcb *unp2) { UNP_PCB_UNLOCK_ASSERT(unp); @@ -720,18 +729,14 @@ uipc_close(struct socket *so) unp->unp_vnode = NULL; } unp2 = unp->unp_conn; - unp_pcb_hold(unp); if (__predict_false(unp == unp2)) { unp_disconnect(unp, unp2); } else if (unp2 != NULL) { - unp_pcb_hold(unp2); unp_pcb_owned_lock2(unp, unp2, freed); unp_disconnect(unp, unp2); - if (unp_pcb_rele(unp2) == 0) - UNP_PCB_UNLOCK(unp2); - } - if (unp_pcb_rele(unp) == 0) + } else { UNP_PCB_UNLOCK(unp); + } if (vp) { mtx_unlock(vplock); vrele(vp); @@ -816,14 +821,11 @@ uipc_detach(struct socket *so) unp2 = NULL; } unp_pcb_hold(unp); - if (unp2 != NULL) { - unp_pcb_hold(unp2); + if (unp2 != NULL) unp_disconnect(unp, unp2); - if (unp_pcb_rele(unp2) == 0) - UNP_PCB_UNLOCK(unp2); - } + else + UNP_PCB_UNLOCK(unp); } - UNP_PCB_UNLOCK(unp); UNP_REF_LIST_LOCK(); while (!LIST_EMPTY(&unp->unp_refs)) { struct unpcb *ref = LIST_FIRST(&unp->unp_refs); @@ -876,14 +878,8 @@ uipc_disconnect(struct socket *so) UNP_PCB_UNLOCK(unp); return (0); } - unp_pcb_hold(unp2); } - unp_pcb_hold(unp); unp_disconnect(unp, unp2); - if (unp_pcb_rele(unp) == 0) - UNP_PCB_UNLOCK(unp); - if ((unp != unp2) && unp_pcb_rele(unp2) == 0) - UNP_PCB_UNLOCK(unp2); return (0); } @@ -1122,9 +1118,8 @@ uipc_send(struct socket *so, int flags, struct mbuf *m } if (nam != NULL) unp_disconnect(unp, unp2); - if (__predict_true(unp != unp2)) - UNP_PCB_UNLOCK(unp2); - UNP_PCB_UNLOCK(unp); + else + unp_pcb_unlock_pair(unp, unp2); break; } @@ -1756,23 +1751,29 @@ static void unp_disconnect(struct unpcb *unp, struct unpcb *unp2) { struct socket *so, *so2; - int freed __unused; +#ifdef INVARIANTS + struct unpcb *unptmp; +#endif - KASSERT(unp2 != NULL, ("unp_disconnect: unp2 == NULL")); - UNP_PCB_LOCK_ASSERT(unp); UNP_PCB_LOCK_ASSERT(unp2); + KASSERT(unp->unp_conn == unp2, + ("%s: unpcb %p is not connected to %p", __func__, unp, unp2)); - if (unp->unp_conn == NULL && unp2->unp_conn == NULL) - return; - - MPASS(unp->unp_conn == unp2); unp->unp_conn = NULL; so = unp->unp_socket; so2 = unp2->unp_socket; switch (unp->unp_socket->so_type) { case SOCK_DGRAM: UNP_REF_LIST_LOCK(); +#ifdef INVARIANTS + LIST_FOREACH(unptmp, &unp2->unp_refs, unp_reflink) { + if (unptmp == unp) + break; + } + KASSERT(unptmp != NULL, + ("%s: %p not found in reflist of %p", __func__, unp, unp2)); +#endif LIST_REMOVE(unp, unp_reflink); UNP_REF_LIST_UNLOCK(); if (so) { @@ -1792,10 +1793,17 @@ unp_disconnect(struct unpcb *unp, struct unpcb *unp2) soisdisconnected(so2); break; } - freed = unp_pcb_rele(unp); - MPASS(freed == 0); - freed = unp_pcb_rele(unp2); - MPASS(freed == 0); + + if (unp == unp2) { + unp_pcb_rele_notlast(unp); + if (!unp_pcb_rele(unp)) + UNP_PCB_UNLOCK(unp); + } else { + if (!unp_pcb_rele(unp)) + UNP_PCB_UNLOCK(unp); + if (!unp_pcb_rele(unp2)) + UNP_PCB_UNLOCK(unp2); + } } /* @@ -1991,17 +1999,17 @@ unp_drop(struct unpcb *unp) if (so) so->so_error = ECONNRESET; unp2 = unp->unp_conn; + /* Last reference dropped in unp_disconnect(). */ if (unp2 == unp) { + unp_pcb_rele_notlast(unp); unp_disconnect(unp, unp2); } else if (unp2 != NULL) { - unp_pcb_hold(unp2); unp_pcb_owned_lock2(unp, unp2, freed); + unp_pcb_rele_notlast(unp); unp_disconnect(unp, unp2); - if (unp_pcb_rele(unp2) == 0) - UNP_PCB_UNLOCK(unp2); - } - if (unp_pcb_rele(unp) == 0) + } else if (!unp_pcb_rele(unp)) { UNP_PCB_UNLOCK(unp); + } } static void _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
