freebsd-nq/sys/netinet6/in6_pcb.h
Robert Watson fa046d8774 Decompose the current single inpcbinfo lock into two locks:
- The existing ipi_lock continues to protect the global inpcb list and
  inpcb counter.  This lock is now relegated to a small number of
  allocation and free operations, and occasional operations that walk
  all connections (including, awkwardly, certain UDP multicast receive
  operations -- something to revisit).

- A new ipi_hash_lock protects the two inpcbinfo hash tables for
  looking up connections and bound sockets, manipulated using new
  INP_HASH_*() macros.  This lock, combined with inpcb locks, protects
  the 4-tuple address space.

Unlike the current ipi_lock, ipi_hash_lock follows the individual inpcb
connection locks, so may be acquired while manipulating a connection on
which a lock is already held, avoiding the need to acquire the inpcbinfo
lock preemptively when a binding change might later be required.  As a
result, however, lookup operations necessarily go through a reference
acquire while holding the lookup lock, later acquiring an inpcb lock --
if required.

A new function in_pcblookup() looks up connections, and accepts flags
indicating how to return the inpcb.  Due to lock order changes, callers
no longer need acquire locks before performing a lookup: the lookup
routine will acquire the ipi_hash_lock as needed.  In the future, it will
also be able to use alternative lookup and locking strategies
transparently to callers, such as pcbgroup lookup.  New lookup flags are,
supplementing the existing INPLOOKUP_WILDCARD flag:

  INPLOOKUP_RLOCKPCB - Acquire a read lock on the returned inpcb
  INPLOOKUP_WLOCKPCB - Acquire a write lock on the returned inpcb

Callers must pass exactly one of these flags (for the time being).

Some notes:

- All protocols are updated to work within the new regime; especially,
  TCP, UDPv4, and UDPv6.  pcbinfo ipi_lock acquisitions are largely
  eliminated, and global hash lock hold times are dramatically reduced
  compared to previous locking.
- The TCP syncache still relies on the pcbinfo lock, something that we
  may want to revisit.
- Support for reverting to the FreeBSD 7.x locking strategy in TCP input
  is no longer available -- hash lookup locks are now held only very
  briefly during inpcb lookup, rather than for potentially extended
  periods.  However, the pcbinfo ipi_lock will still be acquired if a
  connection state might change such that a connection is added or
  removed.
- Raw IP sockets continue to use the pcbinfo ipi_lock for protection,
  due to maintaining their own hash tables.
- The interface in6_pcblookup_hash_locked() is maintained, which allows
  callers to acquire hash locks and perform one or more lookups atomically
  with 4-tuple allocation: this is required only for TCPv6, as there is no
  in6_pcbconnect_setup(), which there should be.
- UDPv6 locking remains significantly more conservative than UDPv4
  locking, which relates to source address selection.  This needs
  attention, as it likely significantly reduces parallelism in this code
  for multithreaded socket use (such as in BIND).
- In the UDPv4 and UDPv6 multicast cases, we need to revisit locking
  somewhat, as they relied on ipi_lock to stablise 4-tuple matches, which
  is no longer sufficient.  A second check once the inpcb lock is held
  should do the trick, keeping the general case from requiring the inpcb
  lock for every inpcb visited.
- This work reminds us that we need to revisit locking of the v4/v6 flags,
  which may be accessed lock-free both before and after this change.
- Right now, a single lock name is used for the pcbhash lock -- this is
  undesirable, and probably another argument is required to take care of
  this (or a char array name field in the pcbinfo?).

This is not an MFC candidate for 8.x due to its impact on lookup and
locking semantics.  It's possible some of these issues could be worked
around with compatibility wrappers, if necessary.

Reviewed by:    bz
Sponsored by:   Juniper Networks, Inc.
2011-05-30 09:43:55 +00:00

109 lines
5.1 KiB
C

/*-
* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the project nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $KAME: in6_pcb.h,v 1.13 2001/02/06 09:16:53 itojun Exp $
*/
/*-
* Copyright (c) 1982, 1986, 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)in_pcb.h 8.1 (Berkeley) 6/10/93
* $FreeBSD$
*/
#ifndef _NETINET6_IN6_PCB_H_
#define _NETINET6_IN6_PCB_H_
#ifdef _KERNEL
#define satosin6(sa) ((struct sockaddr_in6 *)(sa))
#define sin6tosa(sin6) ((struct sockaddr *)(sin6))
#define ifatoia6(ifa) ((struct in6_ifaddr *)(ifa))
void in6_pcbpurgeif0 __P((struct inpcbinfo *, struct ifnet *));
void in6_losing __P((struct inpcb *));
int in6_pcbbind __P((struct inpcb *, struct sockaddr *, struct ucred *));
int in6_pcbconnect __P((struct inpcb *, struct sockaddr *, struct ucred *));
void in6_pcbdisconnect __P((struct inpcb *));
int in6_pcbladdr(struct inpcb *, struct sockaddr *, struct in6_addr *);
struct inpcb *
in6_pcblookup_local __P((struct inpcbinfo *,
struct in6_addr *, u_short, int,
struct ucred *));
struct inpcb *
in6_pcblookup __P((struct inpcbinfo *, struct in6_addr *,
u_int, struct in6_addr *, u_int, int,
struct ifnet *));
struct inpcb *
in6_pcblookup_hash_locked __P((struct inpcbinfo *, struct in6_addr *,
u_int, struct in6_addr *, u_int, int,
struct ifnet *));
void in6_pcbnotify __P((struct inpcbinfo *, struct sockaddr *,
u_int, const struct sockaddr *, u_int, int, void *,
struct inpcb *(*)(struct inpcb *, int)));
struct inpcb *
in6_rtchange __P((struct inpcb *, int));
struct sockaddr *
in6_sockaddr __P((in_port_t port, struct in6_addr *addr_p));
struct sockaddr *
in6_v4mapsin6_sockaddr __P((in_port_t port, struct in_addr *addr_p));
int in6_getpeeraddr __P((struct socket *so, struct sockaddr **nam));
int in6_getsockaddr __P((struct socket *so, struct sockaddr **nam));
int in6_mapped_sockaddr __P((struct socket *so, struct sockaddr **nam));
int in6_mapped_peeraddr __P((struct socket *so, struct sockaddr **nam));
int in6_selecthlim __P((struct in6pcb *, struct ifnet *));
int in6_pcbsetport __P((struct in6_addr *, struct inpcb *, struct ucred *));
void init_sin6 __P((struct sockaddr_in6 *sin6, struct mbuf *m));
#endif /* _KERNEL */
#endif /* !_NETINET6_IN6_PCB_H_ */