Author: rwatson
Date: Mon May 23 13:51:57 2011
New Revision: 222213
URL: http://svn.freebsd.org/changeset/base/222213
Log:
A number of quite incremental refinements to struct inpcbinfo's definition:
(1) Add a locking guide for inpcbinfo.
(2) Annotate inpcbinfo fields with synchronisation information; not all
annotations are 100% satisfactory.
(3) Reorder inpcbinfo fields so that the lock is at the head of the
structure, and close to fields it protects.
(4) Sort fields that will eventually be hashlock/pcbgroup-related together
even though they remain locked by ipi_lock for now.
Reviewed by: bz
Sponsored by: Juniper Networks
X-MFC after: KBI analysis required
Modified:
head/sys/netinet/in_pcb.h
Modified: head/sys/netinet/in_pcb.h
==============================================================================
--- head/sys/netinet/in_pcb.h Mon May 23 13:02:04 2011 (r222212)
+++ head/sys/netinet/in_pcb.h Mon May 23 13:51:57 2011 (r222213)
@@ -1,8 +1,12 @@
/*-
* Copyright (c) 1982, 1986, 1990, 1993
* The Regents of the University of California.
+ * Copyright (c) 2010-2011 Juniper Networks, Inc.
* All rights reserved.
*
+ * Portions of this software were developed by Robert N. M. Watson under
+ * contract to Juniper Networks, Inc.
+ *
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
@@ -260,53 +264,70 @@ struct inpcbport {
u_short phd_port;
};
-/*
+/*-
* Global data structure for each high-level protocol (UDP, TCP, ...) in both
* IPv4 and IPv6. Holds inpcb lists and information for managing them.
+ *
+ * Each pcbinfo is protected by ipi_lock, covering mutable global fields (such
+ * as the global pcb list) and hashed lookup tables. The lock order is:
+ *
+ * ipi_lock (before) inpcb locks
+ *
+ * Locking key:
+ *
+ * (c) Constant or nearly constant after initialisation
+ * (g) Locked by ipi_lock
+ * (h) Read using either ipi_lock or inpcb lock; write requires both.
+ * (x) Synchronisation properties poorly defined
*/
struct inpcbinfo {
/*
- * Global list of inpcbs on the protocol.
+ * Global lock protecting global inpcb list, inpcb count, hash tables,
+ * etc.
*/
- struct inpcbhead *ipi_listhead;
- u_int ipi_count;
+ struct rwlock ipi_lock;
/*
- * Global hash of inpcbs, hashed by local and foreign addresses and
- * port numbers.
+ * Global list of inpcbs on the protocol.
*/
- struct inpcbhead *ipi_hashbase;
- u_long ipi_hashmask;
+ struct inpcbhead *ipi_listhead; /* (g) */
+ u_int ipi_count; /* (g) */
/*
- * Global hash of inpcbs, hashed by only local port number.
+ * Generation count -- incremented each time a connection is allocated
+ * or freed.
*/
- struct inpcbporthead *ipi_porthashbase;
- u_long ipi_porthashmask;
+ u_quad_t ipi_gencnt; /* (g) */
/*
* Fields associated with port lookup and allocation.
*/
- u_short ipi_lastport;
- u_short ipi_lastlow;
- u_short ipi_lasthi;
+ u_short ipi_lastport; /* (x) */
+ u_short ipi_lastlow; /* (x) */
+ u_short ipi_lasthi; /* (x) */
/*
* UMA zone from which inpcbs are allocated for this protocol.
*/
- struct uma_zone *ipi_zone;
+ struct uma_zone *ipi_zone; /* (c) */
/*
- * Generation count--incremented each time a connection is allocated
- * or freed.
+ * Global hash of inpcbs, hashed by local and foreign addresses and
+ * port numbers.
*/
- u_quad_t ipi_gencnt;
- struct rwlock ipi_lock;
+ struct inpcbhead *ipi_hashbase; /* (g) */
+ u_long ipi_hashmask; /* (g) */
+
+ /*
+ * Global hash of inpcbs, hashed by only local port number.
+ */
+ struct inpcbporthead *ipi_porthashbase; /* (g) */
+ u_long ipi_porthashmask; /* (g) */
/*
* Pointer to network stack instance
*/
- struct vnet *ipi_vnet;
+ struct vnet *ipi_vnet; /* (c) */
/*
* general use 2
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