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netlink-socket: Simplify use of transactions and dumps.

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This disentangles "struct nl_dump" from "struct nl_sock", clearing the way
to make the use of either one thread-safe in an obviously correct manner.

Signed-off-by: Ben Pfaff <blp@nicira.com>
This commit is contained in:
Ben Pfaff
2013-04-29 13:57:50 -07:00
parent bb5c146881
commit a88b4e0412
5 changed files with 115 additions and 159 deletions
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20
lib/dpif-linux.c
View File

@@ -162,7 +162,6 @@ static int ovs_flow_family;
static int ovs_packet_family;
/* Generic Netlink socket. */
static struct nl_sock *genl_sock;
static struct nln *nln = NULL;
static int dpif_linux_init(void);
@@ -692,7 +691,7 @@ dpif_linux_port_dump_start(const struct dpif *dpif_, void **statep)
buf = ofpbuf_new(1024);
dpif_linux_vport_to_ofpbuf(&request, buf);
nl_dump_start(&state->dump, genl_sock, buf);
nl_dump_start(&state->dump, NETLINK_GENERIC, buf);
ofpbuf_delete(buf);
return 0;
@@ -898,7 +897,7 @@ dpif_linux_flow_dump_start(const struct dpif *dpif_, void **statep)
buf = ofpbuf_new(1024);
dpif_linux_flow_to_ofpbuf(&request, buf);
nl_dump_start(&state->dump, genl_sock, buf);
nl_dump_start(&state->dump, NETLINK_GENERIC, buf);
ofpbuf_delete(buf);
state->buf = NULL;
@@ -1005,7 +1004,7 @@ dpif_linux_execute__(int dp_ifindex, const struct dpif_execute *execute)
ofpbuf_use_stub(&request, request_stub, sizeof request_stub);
dpif_linux_encode_execute(dp_ifindex, execute, &request);
error = nl_sock_transact(genl_sock, &request, NULL);
error = nl_transact(NETLINK_GENERIC, &request, NULL);
ofpbuf_uninit(&request);
return error;
@@ -1090,7 +1089,7 @@ dpif_linux_operate__(struct dpif *dpif_, struct dpif_op **ops, size_t n_ops)
for (i = 0; i < n_ops; i++) {
txnsp[i] = &auxes[i].txn;
}
nl_sock_transact_multiple(genl_sock, txnsp, n_ops);
nl_transact_multiple(NETLINK_GENERIC, txnsp, n_ops);
for (i = 0; i < n_ops; i++) {
struct op_auxdata *aux = &auxes[i];
@@ -1463,9 +1462,6 @@ dpif_linux_init(void)
error = nl_lookup_genl_family(OVS_PACKET_FAMILY,
&ovs_packet_family);
}
if (!error) {
error = nl_sock_create(NETLINK_GENERIC, &genl_sock);
}
if (!error) {
error = nl_lookup_genl_mcgroup(OVS_VPORT_FAMILY, OVS_VPORT_MCGROUP,
&ovs_vport_mcgroup,
@@ -1659,7 +1655,7 @@ dpif_linux_vport_transact(const struct dpif_linux_vport *request,
request_buf = ofpbuf_new(1024);
dpif_linux_vport_to_ofpbuf(request, request_buf);
error = nl_sock_transact(genl_sock, request_buf, bufp);
error = nl_transact(NETLINK_GENERIC, request_buf, bufp);
ofpbuf_delete(request_buf);
if (reply) {
@@ -1780,7 +1776,7 @@ dpif_linux_dp_dump_start(struct nl_dump *dump)
buf = ofpbuf_new(1024);
dpif_linux_dp_to_ofpbuf(&request, buf);
nl_dump_start(dump, genl_sock, buf);
nl_dump_start(dump, NETLINK_GENERIC, buf);
ofpbuf_delete(buf);
}
@@ -1801,7 +1797,7 @@ dpif_linux_dp_transact(const struct dpif_linux_dp *request,
request_buf = ofpbuf_new(1024);
dpif_linux_dp_to_ofpbuf(request, request_buf);
error = nl_sock_transact(genl_sock, request_buf, bufp);
error = nl_transact(NETLINK_GENERIC, request_buf, bufp);
ofpbuf_delete(request_buf);
if (reply) {
@@ -1965,7 +1961,7 @@ dpif_linux_flow_transact(struct dpif_linux_flow *request,
request_buf = ofpbuf_new(1024);
dpif_linux_flow_to_ofpbuf(request, request_buf);
error = nl_sock_transact(genl_sock, request_buf, bufp);
error = nl_transact(NETLINK_GENERIC, request_buf, bufp);
ofpbuf_delete(request_buf);
if (reply) {

18
lib/netdev-linux.c
View File

@@ -409,9 +409,6 @@ static const struct netdev_rx_class netdev_rx_linux_class;
/* Sockets used for ioctl operations. */
static int af_inet_sock = -1; /* AF_INET, SOCK_DGRAM. */
/* A Netlink routing socket that is not subscribed to any multicast groups. */
static struct nl_sock *rtnl_sock;
/* This is set pretty low because we probably won't learn anything from the
* additional log messages. */
static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 20);
@@ -477,15 +474,6 @@ netdev_linux_init(void)
if (status) {
VLOG_ERR("failed to create inet socket: %s", ovs_strerror(status));
}
/* Create rtnetlink socket. */
if (!status) {
status = nl_sock_create(NETLINK_ROUTE, &rtnl_sock);
if (status) {
VLOG_ERR_RL(&rl, "failed to create rtnetlink socket: %s",
ovs_strerror(status));
}
}
}
return status;
}
@@ -2025,7 +2013,7 @@ start_queue_dump(const struct netdev *netdev, struct nl_dump *dump)
return false;
}
tcmsg->tcm_parent = 0;
nl_dump_start(dump, rtnl_sock, &request);
nl_dump_start(dump, NETLINK_ROUTE, &request);
ofpbuf_uninit(&request);
return true;
}
@@ -3644,7 +3632,7 @@ tc_make_request(const struct netdev *netdev, int type, unsigned int flags,
static int
tc_transact(struct ofpbuf *request, struct ofpbuf **replyp)
{
int error = nl_sock_transact(rtnl_sock, request, replyp);
int error = nl_transact(NETLINK_ROUTE, request, replyp);
ofpbuf_uninit(request);
return error;
}
@@ -4320,7 +4308,7 @@ get_stats_via_netlink(int ifindex, struct netdev_stats *stats)
ifi = ofpbuf_put_zeros(&request, sizeof *ifi);
ifi->ifi_family = PF_UNSPEC;
ifi->ifi_index = ifindex;
error = nl_sock_transact(rtnl_sock, &request, &reply);
error = nl_transact(NETLINK_ROUTE, &request, &reply);
ofpbuf_uninit(&request);
if (error) {
return error;

201
lib/netlink-socket.c
View File

@@ -63,7 +63,6 @@ struct nl_sock {
uint32_t next_seq;
uint32_t pid;
int protocol;
struct nl_dump *dump;
unsigned int rcvbuf; /* Receive buffer size (SO_RCVBUF). */
};
@@ -77,11 +76,12 @@ struct nl_sock {
* Initialized by nl_sock_create(). */
static int max_iovs;
static int nl_sock_cow__(struct nl_sock *);
static int nl_pool_alloc(int protocol, struct nl_sock **sockp);
static void nl_pool_release(struct nl_sock *);
/* Creates a new netlink socket for the given netlink 'protocol'
* (NETLINK_ROUTE, NETLINK_GENERIC, ...). Returns 0 and sets '*sockp' to the
* new socket if successful, otherwise returns a positive errno value. */
* new socket if successful, otherwise returns a positive errno value. */
int
nl_sock_create(int protocol, struct nl_sock **sockp)
{
@@ -117,7 +117,6 @@ nl_sock_create(int protocol, struct nl_sock **sockp)
goto error;
}
sock->protocol = protocol;
sock->dump = NULL;
sock->next_seq = 1;
rcvbuf = 1024 * 1024;
@@ -191,12 +190,8 @@ void
nl_sock_destroy(struct nl_sock *sock)
{
if (sock) {
if (sock->dump) {
sock->dump = NULL;
} else {
close(sock->fd);
free(sock);
}
close(sock->fd);
free(sock);
}
}
@@ -214,10 +209,6 @@ nl_sock_destroy(struct nl_sock *sock)
int
nl_sock_join_mcgroup(struct nl_sock *sock, unsigned int multicast_group)
{
int error = nl_sock_cow__(sock);
if (error) {
return error;
}
if (setsockopt(sock->fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP,
&multicast_group, sizeof multicast_group) < 0) {
VLOG_WARN("could not join multicast group %u (%s)",
@@ -240,7 +231,6 @@ nl_sock_join_mcgroup(struct nl_sock *sock, unsigned int multicast_group)
int
nl_sock_leave_mcgroup(struct nl_sock *sock, unsigned int multicast_group)
{
ovs_assert(!sock->dump);
if (setsockopt(sock->fd, SOL_NETLINK, NETLINK_DROP_MEMBERSHIP,
&multicast_group, sizeof multicast_group) < 0) {
VLOG_WARN("could not leave multicast group %u (%s)",
@@ -301,10 +291,6 @@ int
nl_sock_send_seq(struct nl_sock *sock, const struct ofpbuf *msg,
uint32_t nlmsg_seq, bool wait)
{
int error = nl_sock_cow__(sock);
if (error) {
return error;
}
return nl_sock_send__(sock, msg, nlmsg_seq, wait);
}
@@ -395,10 +381,6 @@ nl_sock_recv__(struct nl_sock *sock, struct ofpbuf *buf, bool wait)
int
nl_sock_recv(struct nl_sock *sock, struct ofpbuf *buf, bool wait)
{
int error = nl_sock_cow__(sock);
if (error) {
return error;
}
return nl_sock_recv__(sock, buf, wait);
}
@@ -571,12 +553,6 @@ nl_sock_transact_multiple(struct nl_sock *sock,
return;
}
error = nl_sock_cow__(sock);
if (error) {
nl_sock_record_errors__(transactions, n, error);
return;
}
/* In theory, every request could have a 64 kB reply. But the default and
* maximum socket rcvbuf size with typical Dom0 memory sizes both tend to
* be a bit below 128 kB, so that would only allow a single message in a
@@ -690,93 +666,36 @@ nl_sock_transact(struct nl_sock *sock, const struct ofpbuf *request,
int
nl_sock_drain(struct nl_sock *sock)
{
int error = nl_sock_cow__(sock);
if (error) {
return error;
}
return drain_rcvbuf(sock->fd);
}
/* The client is attempting some operation on 'sock'. If 'sock' has an ongoing
* dump operation, then replace 'sock''s fd with a new socket and hand 'sock''s
* old fd over to the dump. */
static int
nl_sock_cow__(struct nl_sock *sock)
{
struct nl_sock *copy;
uint32_t tmp_pid;
int tmp_fd;
int error;
if (!sock->dump) {
return 0;
}
error = nl_sock_clone(sock, &copy);
if (error) {
return error;
}
tmp_fd = sock->fd;
sock->fd = copy->fd;
copy->fd = tmp_fd;
tmp_pid = sock->pid;
sock->pid = copy->pid;
copy->pid = tmp_pid;
sock->dump->sock = copy;
sock->dump = NULL;
return 0;
}
/* Starts a Netlink "dump" operation, by sending 'request' to the kernel via
* 'sock', and initializes 'dump' to reflect the state of the operation.
/* Starts a Netlink "dump" operation, by sending 'request' to the kernel on a
* Netlink socket created with the given 'protocol', and initializes 'dump' to
* reflect the state of the operation.
*
* nlmsg_len in 'msg' will be finalized to match msg->size, and nlmsg_pid will
* be set to 'sock''s pid, before the message is sent. NLM_F_DUMP and
* NLM_F_ACK will be set in nlmsg_flags.
* be set to the Netlink socket's pid, before the message is sent. NLM_F_DUMP
* and NLM_F_ACK will be set in nlmsg_flags.
*
* This Netlink socket library is designed to ensure that the dump is reliable
* and that it will not interfere with other operations on 'sock', including
* destroying or sending and receiving messages on 'sock'. One corner case is
* not handled:
*
* - If 'sock' has been used to send a request (e.g. with nl_sock_send())
* whose response has not yet been received (e.g. with nl_sock_recv()).
* This is unusual: usually nl_sock_transact() is used to send a message
* and receive its reply all in one go.
* The design of this Netlink socket library ensures that the dump is reliable.
*
* This function provides no status indication. An error status for the entire
* dump operation is provided when it is completed by calling nl_dump_done().
*
* The caller is responsible for destroying 'request'.
*
* The new 'dump' is independent of 'sock'. 'sock' and 'dump' may be destroyed
* in either order.
*/
void
nl_dump_start(struct nl_dump *dump,
struct nl_sock *sock, const struct ofpbuf *request)
nl_dump_start(struct nl_dump *dump, int protocol, const struct ofpbuf *request)
{
ofpbuf_init(&dump->buffer, 4096);
if (sock->dump) {
/* 'sock' already has an ongoing dump. Clone the socket because
* Netlink only allows one dump at a time. */
dump->status = nl_sock_clone(sock, &dump->sock);
if (dump->status) {
return;
}
} else {
sock->dump = dump;
dump->sock = sock;
dump->status = 0;
dump->status = nl_pool_alloc(protocol, &dump->sock);
if (dump->status) {
return;
}
nl_msg_nlmsghdr(request)->nlmsg_flags |= NLM_F_DUMP | NLM_F_ACK;
dump->status = nl_sock_send__(sock, request, nl_sock_allocate_seq(sock, 1),
true);
dump->status = nl_sock_send__(dump->sock, request,
nl_sock_allocate_seq(dump->sock, 1), true);
dump->seq = nl_msg_nlmsghdr(request)->nlmsg_seq;
}
@@ -862,21 +781,16 @@ int
nl_dump_done(struct nl_dump *dump)
{
/* Drain any remaining messages that the client didn't read. Otherwise the
* kernel will continue to queue them up and waste buffer space. */
* kernel will continue to queue them up and waste buffer space.
*
* XXX We could just destroy and discard the socket in this case. */
while (!dump->status) {
struct ofpbuf reply;
if (!nl_dump_next(dump, &reply)) {
ovs_assert(dump->status);
}
}
if (dump->sock) {
if (dump->sock->dump) {
dump->sock->dump = NULL;
} else {
nl_sock_destroy(dump->sock);
}
}
nl_pool_release(dump->sock);
ofpbuf_uninit(&dump->buffer);
return dump->status == EOF ? 0 : dump->status;
}
@@ -1089,6 +1003,79 @@ nl_lookup_genl_family(const char *name, int *number)
}
return *number > 0 ? 0 : -*number;
}
struct nl_pool {
struct nl_sock *socks[16];
int n;
};
static struct nl_pool pools[MAX_LINKS];
static int
nl_pool_alloc(int protocol, struct nl_sock **sockp)
{
struct nl_pool *pool;
ovs_assert(protocol >= 0 && protocol < ARRAY_SIZE(pools));
pool = &pools[protocol];
if (pool->n > 0) {
*sockp = pool->socks[--pool->n];
return 0;
} else {
return nl_sock_create(protocol, sockp);
}
}
static void
nl_pool_release(struct nl_sock *sock)
{
if (sock) {
struct nl_pool *pool = &pools[sock->protocol];
if (pool->n < ARRAY_SIZE(pool->socks)) {
pool->socks[pool->n++] = sock;
} else {
nl_sock_destroy(sock);
}
}
}
int
nl_transact(int protocol, const struct ofpbuf *request,
struct ofpbuf **replyp)
{
struct nl_sock *sock;
int error;
error = nl_pool_alloc(protocol, &sock);
if (error) {
*replyp = NULL;
return error;
}
error = nl_sock_transact(sock, request, replyp);
nl_pool_release(sock);
return error;
}
void
nl_transact_multiple(int protocol,
struct nl_transaction **transactions, size_t n)
{
struct nl_sock *sock;
int error;
error = nl_pool_alloc(protocol, &sock);
if (!error) {
nl_sock_transact_multiple(sock, transactions, n);
nl_pool_release(sock);
} else {
nl_sock_record_errors__(transactions, n, error);
}
}
static uint32_t
nl_sock_allocate_seq(struct nl_sock *sock, unsigned int n)

9
lib/netlink-socket.h
View File

@@ -1,5 +1,5 @@
/*
* Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira, Inc.
* Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -84,6 +84,11 @@ struct nl_transaction {
void nl_sock_transact_multiple(struct nl_sock *,
struct nl_transaction **, size_t n);
/* Transactions without an allocated socket. */
int nl_transact(int protocol, const struct ofpbuf *request,
struct ofpbuf **replyp);
void nl_transact_multiple(int protocol, struct nl_transaction **, size_t n);
/* Table dumping. */
struct nl_dump {
struct nl_sock *sock; /* Socket being dumped. */
@@ -92,7 +97,7 @@ struct nl_dump {
int status; /* 0=OK, EOF=done, or positive errno value. */
};
void nl_dump_start(struct nl_dump *, struct nl_sock *,
void nl_dump_start(struct nl_dump *, int protocol,
const struct ofpbuf *request);
bool nl_dump_next(struct nl_dump *, struct ofpbuf *reply);
int nl_dump_done(struct nl_dump *);

26
lib/route-table.c
View File

@@ -221,22 +221,13 @@ route_table_wait(void)
static int
route_table_reset(void)
{
int error;
struct nl_dump dump;
struct rtgenmsg *rtmsg;
struct ofpbuf request, reply;
struct nl_sock *rtnl_sock;
route_map_clear();
route_table_valid = true;
error = nl_sock_create(NETLINK_ROUTE, &rtnl_sock);
if (error) {
VLOG_WARN_RL(&rl, "failed to reset routing table, "
"cannot create RTNETLINK_ROUTE socket");
return error;
}
ofpbuf_init(&request, 0);
nl_msg_put_nlmsghdr(&request, sizeof *rtmsg, RTM_GETROUTE, NLM_F_REQUEST);
@@ -244,7 +235,7 @@ route_table_reset(void)
rtmsg = ofpbuf_put_zeros(&request, sizeof *rtmsg);
rtmsg->rtgen_family = AF_INET;
nl_dump_start(&dump, rtnl_sock, &request);
nl_dump_start(&dump, NETLINK_ROUTE, &request);
ofpbuf_uninit(&request);
while (nl_dump_next(&dump, &reply)) {
@@ -255,10 +246,7 @@ route_table_reset(void)
}
}
error = nl_dump_done(&dump);
nl_sock_destroy(rtnl_sock);
return error;
return nl_dump_done(&dump);
}
@@ -417,26 +405,19 @@ name_table_uninit(void)
static int
name_table_reset(void)
{
int error;
struct nl_dump dump;
struct rtgenmsg *rtmsg;
struct ofpbuf request, reply;
struct nl_sock *rtnl_sock;
name_table_valid = true;
name_map_clear();
error = nl_sock_create(NETLINK_ROUTE, &rtnl_sock);
if (error) {
VLOG_WARN_RL(&rl, "failed to create NETLINK_ROUTE socket");
return error;
}
ofpbuf_init(&request, 0);
nl_msg_put_nlmsghdr(&request, sizeof *rtmsg, RTM_GETLINK, NLM_F_REQUEST);
rtmsg = ofpbuf_put_zeros(&request, sizeof *rtmsg);
rtmsg->rtgen_family = AF_INET;
nl_dump_start(&dump, rtnl_sock, &request);
nl_dump_start(&dump, NETLINK_ROUTE, &request);
ofpbuf_uninit(&request);
while (nl_dump_next(&dump, &reply)) {
@@ -453,7 +434,6 @@ name_table_reset(void)
hmap_insert(&name_map, &nn->node, hash_int(nn->ifi_index, 0));
}
}
nl_sock_destroy(rtnl_sock);
return nl_dump_done(&dump);
}