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Provide some initial chicken-scratching annotations of locking for

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struct inpcb.

Prodded by:	bz
MFC after:	3 days
This commit is contained in:
rwatson 2008-07-08 17:22:59 +00:00
parent 0abee8ada4
commit e31c8aa8e5
1 changed files with 59 additions and 27 deletions
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86
sys/netinet/in_pcb.h
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@ -115,17 +115,49 @@ struct in_conninfo {
struct icmp6_filter;
/*-
* struct inpcb captures the network layer state for TCP, UDP, and raw IPv4
* and IPv6 sockets. In the case of TCP, further per-connection state is
* hung off of inp_ppcb most of the time. Almost all fields of struct inpcb
* are static after creation or protected by a per-inpcb rwlock, inp_lock. A
* few fields also require the global pcbinfo lock for the inpcb to be held,
* when modified, such as the global connection lists and hashes, as well as
* binding information (which affects which hash a connection is on). This
* model means that connections can be looked up without holding the
* per-connection lock, which is important for performance when attempting to
* find the connection for a packet given its IP and port tuple. Writing to
* these fields that write locks be held on both the inpcb and global locks.
*
* Key:
* (c) - Constant after initialization
* (i) - Protected by the inpcb lock
* (p) - Protected by the pcbinfo lock for the inpcb
* (s) - Protected by another subsystem's locks
* (x) - Undefined locking
*
* A few other notes:
*
* When a read lock is held, stability of the field is guaranteed; to write
* to a field, a write lock must generally be held.
*
* netinet/netinet6-layer code should not assume that the inp_socket pointer
* is safe to dereference without inp_lock being held, even for protocols
* other than TCP (where the inpcb persists during TIMEWAIT even after the
* socket has been freed), or there may be close(2)-related races.
*
* The inp_vflag field is overloaded, and would otherwise ideally be (c).
*/
struct inpcb {
LIST_ENTRY(inpcb) inp_hash; /* hash list */
LIST_ENTRY(inpcb) inp_list; /* list for all PCBs of this proto */
void *inp_ppcb; /* pointer to per-protocol pcb */
struct inpcbinfo *inp_pcbinfo; /* PCB list info */
struct socket *inp_socket; /* back pointer to socket */
LIST_ENTRY(inpcb) inp_hash; /* (i/p) hash list */
LIST_ENTRY(inpcb) inp_list; /* (i/p) list for all PCBs for proto */
void *inp_ppcb; /* (i) pointer to per-protocol pcb */
struct inpcbinfo *inp_pcbinfo; /* (c) PCB list info */
struct socket *inp_socket; /* (i) back pointer to socket */
u_int32_t inp_flow;
int inp_flags; /* generic IP/datagram flags */
u_int32_t inp_flow; /* (i) IPv6 flow information */
int inp_flags; /* (i) generic IP/datagram flags */
u_char inp_vflag; /* IP version flag (v4/v6) */
u_char inp_vflag; /* (i) IP version flag (v4/v6) */
#define INP_IPV4 0x1
#define INP_IPV6 0x2
#define INP_IPV6PROTO 0x4 /* opened under IPv6 protocol */
@ -133,24 +165,24 @@ struct inpcb {
#define INP_ONESBCAST 0x10 /* send all-ones broadcast */
#define INP_DROPPED 0x20 /* protocol drop flag */
#define INP_SOCKREF 0x40 /* strong socket reference */
u_char inp_ip_ttl; /* time to live proto */
u_char inp_ip_p; /* protocol proto */
u_char inp_ip_minttl; /* minimum TTL or drop */
uint32_t inp_ispare1; /* connection id / queue id */
void *inp_pspare[2]; /* rtentry / general use */
u_char inp_ip_ttl; /* (i) time to live proto */
u_char inp_ip_p; /* (c) protocol proto */
u_char inp_ip_minttl; /* (i) minimum TTL or drop */
uint32_t inp_ispare1; /* (x) connection id / queue id */
void *inp_pspare[2]; /* (x) rtentry / general use */
/* Local and foreign ports, local and foreign addr. */
struct in_conninfo inp_inc;
/* list for this PCB's local port */
struct label *inp_label; /* MAC label */
struct inpcbpolicy *inp_sp; /* for IPSEC */
/* (i/p) list for PCB's local port */
struct label *inp_label; /* (i) MAC label */
struct inpcbpolicy *inp_sp; /* (s) for IPSEC */
/* Protocol-dependent part; options. */
struct {
u_char inp4_ip_tos; /* type of service proto */
struct mbuf *inp4_options; /* IP options */
struct ip_moptions *inp4_moptions; /* IP multicast options */
u_char inp4_ip_tos; /* (i) type of service proto */
struct mbuf *inp4_options; /* (i) IP options */
struct ip_moptions *inp4_moptions; /* (i) IP multicast options */
} inp_depend4;
#define inp_fport inp_inc.inc_fport
#define inp_lport inp_inc.inc_lport
@ -160,22 +192,22 @@ struct inpcb {
#define inp_options inp_depend4.inp4_options
#define inp_moptions inp_depend4.inp4_moptions
struct {
/* IP options */
/* (i) IP options */
struct mbuf *inp6_options;
/* IP6 options for outgoing packets */
/* (i) IP6 options for outgoing packets */
struct ip6_pktopts *inp6_outputopts;
/* IP multicast options */
/* (i) IP multicast options */
struct ip6_moptions *inp6_moptions;
/* ICMPv6 code type filter */
/* (i) ICMPv6 code type filter */
struct icmp6_filter *inp6_icmp6filt;
/* IPV6_CHECKSUM setsockopt */
/* (i) IPV6_CHECKSUM setsockopt */
int inp6_cksum;
short inp6_hops;
} inp_depend6;
LIST_ENTRY(inpcb) inp_portlist;
struct inpcbport *inp_phd; /* head of this list */
LIST_ENTRY(inpcb) inp_portlist; /* (i/p) */
struct inpcbport *inp_phd; /* (i/p) head of this list */
#define inp_zero_size offsetof(struct inpcb, inp_gencnt)
inp_gen_t inp_gencnt; /* generation count of this instance */
inp_gen_t inp_gencnt; /* (c) generation count of this instance */
struct rwlock inp_lock;
#define in6p_faddr inp_inc.inc6_faddr