[ovs-dev] [threads 03/28] netlink-socket: Simplify use of transactions and dumps.
Ben Pfaff
blp at nicira.com
Wed Jul 10 23:03:45 UTC 2013
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 at nicira.com>
---
lib/dpif-linux.c | 20 ++---
lib/netdev-linux.c | 18 +----
lib/netlink-socket.c | 201 +++++++++++++++++++++++--------------------------
lib/netlink-socket.h | 9 ++-
lib/route-table.c | 26 +------
5 files changed, 115 insertions(+), 159 deletions(-)
diff --git a/lib/dpif-linux.c b/lib/dpif-linux.c
index 804a90f..958873c 100644
--- a/lib/dpif-linux.c
+++ b/lib/dpif-linux.c
@@ -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];
@@ -1464,9 +1463,6 @@ dpif_linux_init(void)
&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,
OVS_VPORT_MCGROUP_FALLBACK_ID);
@@ -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) {
diff --git a/lib/netdev-linux.c b/lib/netdev-linux.c
index 8790f14..197e51d 100644
--- a/lib/netdev-linux.c
+++ b/lib/netdev-linux.c
@@ -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;
}
@@ -2027,7 +2015,7 @@ 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;
}
@@ -3646,7 +3634,7 @@ 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;
}
@@ -4322,7 +4310,7 @@ 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;
diff --git a/lib/netlink-socket.c b/lib/netlink-socket.c
index aa7fca2..8e08841 100644
--- a/lib/netlink-socket.c
+++ b/lib/netlink-socket.c
@@ -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, ©);
- 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.
- *
- * 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:
+ * 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.
*
- * - 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;
}
@@ -1090,6 +1004,79 @@ 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)
{
diff --git a/lib/netlink-socket.h b/lib/netlink-socket.h
index 78dd7b2..c77050e 100644
--- a/lib/netlink-socket.h
+++ b/lib/netlink-socket.h
@@ -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 *);
diff --git a/lib/route-table.c b/lib/route-table.c
index 5891ae8..d572e8c 100644
--- a/lib/route-table.c
+++ b/lib/route-table.c
@@ -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);
}
--
1.7.2.5
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