Add per-net sysctl tunables to set the size of sndbuf and
rcvbuf on the kernel tcp socket.
The tunables are added at /proc/sys/net/rds/tcp/rds_tcp_sndbuf
and /proc/sys/net/rds/tcp/rds_tcp_rcvbuf.
Since these values must be set before accept() or connect(),
and there may be an arbitrary number of existing rds-tcp
sockets when the tunable is modified. To make sure that all
connections in the netns pick up the same value for the tunable,
we reset existing rds-tcp connections in the netns, so that
they can reconnect with the new parameters.
Signed-off-by: Sowmini Varadhan <sowmini.varad...@oracle.com>
---
v2; use sysctl instead of module param. Tunabes are now per netns,
and can be dynamically modified without restarting all namespaces.
v3: review comments from Santosh Shilimkar, Eric Dumazet
net/rds/tcp.c | 143 +++++++++++++++++++++++++++++++++++++++++++++++++++++----
1 files changed, 134 insertions(+), 9 deletions(-)
diff --git a/net/rds/tcp.c b/net/rds/tcp.c
index ad60299..b720b25 100644
--- a/net/rds/tcp.c
+++ b/net/rds/tcp.c
@@ -54,6 +54,28 @@ static struct kmem_cache *rds_tcp_conn_slab;
#define RDS_TCP_DEFAULT_BUFSIZE (128 * 1024)
+static int sndbuf_handler(struct ctl_table *ctl, int write,
+ void __user *buffer, size_t *lenp, loff_t *fpos);
+static int rcvbuf_handler(struct ctl_table *ctl, int write,
+ void __user *buffer, size_t *lenp, loff_t *fpos);
+static struct ctl_table rds_tcp_sysctl_table[] = {
+ {
+ .procname = "rds_tcp_sndbuf",
+ /* data is per-net pointer */
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = sndbuf_handler,
+ },
+ {
+ .procname = "rds_tcp_rcvbuf",
+ /* data is per-net pointer */
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = rcvbuf_handler,
+ },
+ { }
+};
+
/* doing it this way avoids calling tcp_sk() */
void rds_tcp_nonagle(struct socket *sock)
{
@@ -66,15 +88,6 @@ void rds_tcp_nonagle(struct socket *sock)
set_fs(oldfs);
}
-/* All module specific customizations to the RDS-TCP socket should be done in
- * rds_tcp_tune() and applied after socket creation. In general these
- * customizations should be tunable via module_param()
- */
-void rds_tcp_tune(struct socket *sock)
-{
- rds_tcp_nonagle(sock);
-}
-
u32 rds_tcp_snd_nxt(struct rds_tcp_connection *tc)
{
return tcp_sk(tc->t_sock->sk)->snd_nxt;
@@ -272,8 +285,33 @@ static int rds_tcp_netid;
struct rds_tcp_net {
struct socket *rds_tcp_listen_sock;
struct work_struct rds_tcp_accept_w;
+ struct ctl_table_header *rds_tcp_sysctl;
+ int sndbuf_size;
+ int rcvbuf_size;
};
+/* All module specific customizations to the RDS-TCP socket should be done in
+ * rds_tcp_tune() and applied after socket creation.
+ */
+void rds_tcp_tune(struct socket *sock)
+{
+ struct sock *sk = sock->sk;
+ struct net *net = sock_net(sk);
+ struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
+
+ rds_tcp_nonagle(sock);
+ lock_sock(sk);
+ if (rtn->sndbuf_size > 0) {
+ sk->sk_sndbuf = rtn->sndbuf_size;
+ sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
+ }
+ if (rtn->rcvbuf_size > 0) {
+ sk->sk_sndbuf = rtn->rcvbuf_size;
+ sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
+ }
+ release_sock(sk);
+}
+
static void rds_tcp_accept_worker(struct work_struct *work)
{
struct rds_tcp_net *rtn = container_of(work,
@@ -296,9 +334,17 @@ static __net_init int rds_tcp_init_net(struct net *net)
{
struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
+ /* 0 value for {snd, rcv}buf_size implies we let the stack
+ * pick the default, and permit auto-tuning of buffer size.
+ */
+ rtn->sndbuf_size = 0;
+ rtn->rcvbuf_size = 0;
+ rtn->rds_tcp_sysctl = register_net_sysctl(net, "net/rds/tcp",
+ rds_tcp_sysctl_table);
rtn->rds_tcp_listen_sock = rds_tcp_listen_init(net);
if (!rtn->rds_tcp_listen_sock) {
pr_warn("could not set up listen sock\n");
+ unregister_net_sysctl_table(rtn->rds_tcp_sysctl);
return -EAFNOSUPPORT;
}
INIT_WORK(&rtn->rds_tcp_accept_w, rds_tcp_accept_worker);
@@ -309,6 +355,7 @@ static void __net_exit rds_tcp_exit_net(struct net *net)
{
struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
+ unregister_net_sysctl_table(rtn->rds_tcp_sysctl);
/* If rds_tcp_exit_net() is called as a result of netns deletion,
* the rds_tcp_kill_sock() device notifier would already have cleaned
* up the listen socket, thus there is no work to do in this function.
@@ -383,6 +430,84 @@ static struct notifier_block rds_tcp_dev_notifier = {
.priority = -10, /* must be called after other network notifiers */
};
+static int user_atoi(char __user *ubuf, size_t len)
+{
+ char buf[16];
+ unsigned long ret;
+ int err;
+
+ if (len > 15)
+ return -EINVAL;
+
+ if (copy_from_user(buf, ubuf, len))
+ return -EFAULT;
+
+ buf[len] = 0;
+ err = kstrtoul(buf, 0, &ret);
+ if (err != 0)
+ return -ERANGE;
+ return ret;
+}
+
+/* when sysctl is used to modify some kernel socket parameters,this
+ * function resets the RDS connections in that netns so that we can
+ * restart with new parameters. The assumption is that such reset
+ * events are few and far-between.
+ */
+static void rds_tcp_sysctl_reset(struct net *net)
+{
+ struct rds_tcp_connection *tc, *_tc;
+
+ spin_lock_irq(&rds_tcp_conn_lock);
+ list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
+ struct net *c_net = read_pnet(&tc->conn->c_net);
+
+ if (net != c_net || !tc->t_sock)
+ continue;
+
+ rds_conn_drop(tc->conn); /* reconnect with new parameters */
+ }
+ spin_unlock_irq(&rds_tcp_conn_lock);
+}
+
+static int sndbuf_handler(struct ctl_table *ctl, int write,
+ void __user *buffer, size_t *lenp, loff_t *fpos)
+{
+ struct net *net = current->nsproxy->net_ns;
+ struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
+ struct ctl_table tmp;
+
+ tmp = *ctl;
+ tmp.data = &rtn->sndbuf_size;
+ if (!write)
+ return proc_dointvec(&tmp, write, buffer, lenp, fpos);
+
+ rtn->sndbuf_size = max_t(u32, user_atoi(buffer, *lenp) * 2,
+ SOCK_MIN_SNDBUF);
+ rds_tcp_sysctl_reset(net);
+
+ return 0;
+}
+
+static int rcvbuf_handler(struct ctl_table *ctl, int write,
+ void __user *buffer, size_t *lenp, loff_t *fpos)
+{
+ struct net *net = current->nsproxy->net_ns;
+ struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
+ struct ctl_table tmp;
+
+ tmp = *ctl;
+ tmp.data = &rtn->rcvbuf_size;
+ if (!write)
+ return proc_dointvec(&tmp, write, buffer, lenp, fpos);
+
+ rtn->rcvbuf_size = max_t(u32, user_atoi(buffer, *lenp) * 2,
+ SOCK_MIN_RCVBUF);
+ rds_tcp_sysctl_reset(net);
+
+ return 0;
+}
+
static void rds_tcp_exit(void)
{
rds_info_deregister_func(RDS_INFO_TCP_SOCKETS, rds_tcp_tc_info);
--
1.7.1
