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Simplify unp_disconnect() callers.

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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
This commit is contained in:
Mark Johnston 2020-09-15 19:22:37 +00:00
parent 4820bf6ac2
commit f0317f868b
1 changed files with 45 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

82
sys/kern/uipc_usrreq.c
View File

@ -334,6 +334,15 @@ unp_pcb_rele(struct unpcb *unp)
return (ret);
}
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)
{
@ -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, struct sockaddr *nam,
}
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;
KASSERT(unp2 != NULL, ("unp_disconnect: unp2 == NULL"));
#ifdef INVARIANTS
struct unpcb *unptmp;
#endif
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