socket: Add assertions around naked refcount decrements
Sockets in a listen queue hold a reference to the parent listening socket. Several code paths release this reference manually when moving a child socket out of the queue. Replace comments about the expected post-decrement refcount value with assertions. Use refcount_load() instead of a plain load. No functional change intended. MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D31974
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@ -1120,11 +1120,12 @@ void
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sofree(struct socket *so)
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{
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struct protosw *pr = so->so_proto;
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bool last __diagused;
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SOCK_LOCK_ASSERT(so);
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if ((so->so_state & SS_NOFDREF) == 0 || so->so_count != 0 ||
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(so->so_state & SS_PROTOREF) || (so->so_qstate == SQ_COMP)) {
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if ((so->so_state & (SS_NOFDREF | SS_PROTOREF)) != SS_NOFDREF ||
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refcount_load(&so->so_count) != 0 || so->so_qstate == SQ_COMP) {
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SOCK_UNLOCK(so);
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return;
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}
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@ -1160,8 +1161,9 @@ sofree(struct socket *so)
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__func__, so, sol));
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TAILQ_REMOVE(&sol->sol_incomp, so, so_list);
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sol->sol_incqlen--;
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/* This is guarenteed not to be the last. */
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refcount_release(&sol->so_count);
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last = refcount_release(&sol->so_count);
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KASSERT(!last, ("%s: released last reference for %p",
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__func__, sol));
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so->so_qstate = SQ_NONE;
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so->so_listen = NULL;
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} else
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@ -1169,7 +1171,7 @@ sofree(struct socket *so)
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("%s: so %p not on (in)comp with so_listen",
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__func__, so));
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sorele(sol);
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KASSERT(so->so_count == 1,
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KASSERT(refcount_load(&so->so_count) == 1,
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("%s: so %p count %u", __func__, so, so->so_count));
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so->so_count = 0;
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}
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@ -1225,6 +1227,7 @@ soclose(struct socket *so)
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struct accept_queue lqueue;
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struct socket *sp, *tsp;
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int error = 0;
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bool last __diagused;
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KASSERT(!(so->so_state & SS_NOFDREF), ("soclose: SS_NOFDREF on enter"));
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@ -1271,8 +1274,9 @@ soclose(struct socket *so)
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sp->so_qstate = SQ_NONE;
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sp->so_listen = NULL;
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SOCK_UNLOCK(sp);
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/* Guaranteed not to be the last. */
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refcount_release(&so->so_count);
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last = refcount_release(&so->so_count);
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KASSERT(!last, ("%s: released last reference for %p",
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__func__, so));
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}
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}
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KASSERT((so->so_state & SS_NOFDREF) == 0, ("soclose: NOFDREF"));
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@ -1284,7 +1288,7 @@ soclose(struct socket *so)
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SOCK_UNLOCK(sp);
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soabort(sp);
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} else {
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/* sp is now in sofree() */
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/* See the handling of queued sockets in sofree(). */
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SOCK_UNLOCK(sp);
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}
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}
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@ -4010,6 +4014,7 @@ soisconnecting(struct socket *so)
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void
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soisconnected(struct socket *so)
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{
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bool last __diagused;
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SOCK_LOCK(so);
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so->so_state &= ~(SS_ISCONNECTING|SS_ISDISCONNECTING|SS_ISCONFIRMING);
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@ -4042,8 +4047,9 @@ soisconnected(struct socket *so)
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sorele(head);
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return;
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}
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/* Not the last one, as so holds a ref. */
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refcount_release(&head->so_count);
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last = refcount_release(&head->so_count);
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KASSERT(!last, ("%s: released last reference for %p",
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__func__, head));
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}
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again:
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if ((so->so_options & SO_ACCEPTFILTER) == 0) {
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