From f41dd6dca9808ff82d32c59f65bf64128bcc2f9a Mon Sep 17 00:00:00 2001 From: Robert Watson Date: Thu, 8 Oct 2009 11:07:15 +0000 Subject: [PATCH] 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 Reviewed by: bz Approved by: re (kib) --- sys/netinet/tcp_input.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c index 470d782ee5e..586a60ccbfc 100644 --- a/sys/netinet/tcp_input.c +++ b/sys/netinet/tcp_input.c @@ -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++;