Author: rwatson
Date: Thu Oct 8 11:07:15 2009
New Revision: 197854
URL: http://svn.freebsd.org/changeset/base/197854
Log:
Merge r197795 from head to stable/8:
In tcp_input(), we acquire a global write lock at first only if a
segment is likely to trigger a TCP state change (i.e., FIN/RST/SYN).
If we later have to upgrade the lock, we acquire an inpcb reference
and drop both global/inpcb locks before reacquiring in-order. In
that gap, the connection may transition into TIMEWAIT, so we need
to loop back and reevaluate the inpcb after relocking.
Reported by: Kamigishi Rei <spambox at haruhiism.net>
Reviewed by: bz
Approved by: re (kib)
Modified:
stable/8/sys/ (props changed)
stable/8/sys/amd64/include/xen/ (props changed)
stable/8/sys/cddl/contrib/opensolaris/ (props changed)
stable/8/sys/contrib/dev/acpica/ (props changed)
stable/8/sys/contrib/pf/ (props changed)
stable/8/sys/dev/xen/xenpci/ (props changed)
stable/8/sys/netinet/tcp_input.c
Modified: stable/8/sys/netinet/tcp_input.c
==============================================================================
--- stable/8/sys/netinet/tcp_input.c Thu Oct 8 10:26:49 2009
(r197853)
+++ stable/8/sys/netinet/tcp_input.c Thu Oct 8 11:07:15 2009
(r197854)
@@ -648,6 +648,7 @@ findpcb:
* tried to free the inpcb, in which case we need to loop back and
* try to find a new inpcb to deliver to.
*/
+relocked:
if (inp->inp_flags & INP_TIMEWAIT) {
KASSERT(ti_locked == TI_RLOCKED || ti_locked == TI_WLOCKED,
("%s: INP_TIMEWAIT ti_locked %d", __func__, ti_locked));
@@ -698,7 +699,8 @@ findpcb:
* We've identified a valid inpcb, but it could be that we need an
* inpcbinfo write lock and have only a read lock. In this case,
* attempt to upgrade/relock using the same strategy as the TIMEWAIT
- * case above.
+ * case above. If we relock, we have to jump back to 'relocked' as
+ * the connection might now be in TIMEWAIT.
*/
if (tp->t_state != TCPS_ESTABLISHED ||
(thflags & (TH_SYN | TH_FIN | TH_RST)) != 0 ||
@@ -720,6 +722,7 @@ findpcb:
goto findpcb;
}
tcp_wlock_relocked++;
+ goto relocked;
} else {
ti_locked = TI_WLOCKED;
tcp_wlock_upgraded++;
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