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Index: head/sys/netinet/udp_usrreq.c
===================================================================
--- head/sys/netinet/udp_usrreq.c
+++ head/sys/netinet/udp_usrreq.c
@@ -1258,20 +1258,22 @@
}
/*
- * Depending on whether or not the application has bound or connected
- * the socket, we may have to do varying levels of work. The optimal
- * case is for a connected UDP socket, as a global lock isn't
- * required at all.
- *
- * In order to decide which we need, we require stability of the
- * inpcb binding, which we ensure by acquiring a read lock on the
- * inpcb. This doesn't strictly follow the lock order, so we play
- * the trylock and retry game; note that we may end up with more
- * conservative locks than required the second time around, so later
- * assertions have to accept that. Further analysis of the number of
- * misses under contention is required.
- *
- * XXXRW: Check that hash locking update here is correct.
+ * In the old days, depending on whether or not the application had
+ * bound or connected the socket, we had to do varying levels of work.
+ * The optimal case was for a connected UDP socket, as a global lock
+ * wasn't required at all.
+ * In order to decide which we need, we required stability of the
+ * inpcb binding, which we ensured by acquiring a read lock on the
+ * inpcb. This didn't strictly follow the lock order, so we played
+ * the trylock and retry game.
+ * With the re-introduction of the route-cache in some cases, we started
+ * to acquire an early inp wlock and a possible race during re-lock
+ * went away. With the introduction of epoch(9) some read locking
+ * became epoch(9) and the lock-order issues also went away.
+ * Due to route-cache we may now hold more conservative locks than
+ * otherwise required and have split up the 2nd case in case 2 and 3
+ * in order to keep the udpinfo lock level in sync with the inp one
+ * for the IP_SENDSRCADDR case below.
*/
pr = inp->inp_socket->so_proto->pr_protocol;
pcbinfo = udp_get_inpcbinfo(pr);
@@ -1279,14 +1281,21 @@
(inp->inp_laddr.s_addr == INADDR_ANY && inp->inp_lport == 0)) {
INP_HASH_WLOCK(pcbinfo);
unlock_udbinfo = UH_WLOCKED;
- } else if ((sin != NULL &&
- (sin->sin_addr.s_addr == INADDR_ANY ||
- sin->sin_addr.s_addr == INADDR_BROADCAST ||
- inp->inp_laddr.s_addr == INADDR_ANY ||
- inp->inp_lport == 0)) ||
- src.sin_family == AF_INET) {
+ } else if (sin != NULL &&
+ (sin->sin_addr.s_addr == INADDR_ANY ||
+ sin->sin_addr.s_addr == INADDR_BROADCAST ||
+ inp->inp_laddr.s_addr == INADDR_ANY ||
+ inp->inp_lport == 0)) {
INP_HASH_RLOCK_ET(pcbinfo, et);
unlock_udbinfo = UH_RLOCKED;
+ } else if (src.sin_family == AF_INET) {
+ if (unlock_inp == UH_WLOCKED) {
+ INP_HASH_WLOCK(pcbinfo);
+ unlock_udbinfo = UH_WLOCKED;
+ } else {
+ INP_HASH_RLOCK_ET(pcbinfo, et);
+ unlock_udbinfo = UH_RLOCKED;
+ }
} else
unlock_udbinfo = UH_UNLOCKED;

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