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RDS: TCP: Refactor connection destruction to handle multiple paths 

A single rds_connection may have multiple rds_conn_paths that have
to be carefully and correctly destroyed, for both rmmod and
netns-delete cases.

For both cases, we extract a single rds_tcp_connection for
each conn into a temporary list, and then invoke rds_conn_destroy()
which iteratively dismantles every path in the rds_connection.

For the netns deletion case, we additionally have to make sure
that we do not leave a socket in TIME_WAIT state, as this will
hold up the netns deletion. Thus we call rds_tcp_conn_paths_destroy()
to reset state quickly.

Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Sowmini Varadhan 2016-06-30 16:11:13 -07:00 committed by David S. Miller
parent 02105b2ccd
commit afb4164d91
1 changed files with 39 additions and 7 deletions
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46
net/rds/tcp.c
View File

@ -323,6 +323,17 @@ static void rds_tcp_conn_free(void *arg)
kmem_cache_free(rds_tcp_conn_slab, tc);
}
static bool list_has_conn(struct list_head *list, struct rds_connection *conn)
{
struct rds_tcp_connection *tc, *_tc;
list_for_each_entry_safe(tc, _tc, list, t_tcp_node) {
if (tc->t_cpath->cp_conn == conn)
return true;
}
return false;
}
static void rds_tcp_destroy_conns(void)
{
struct rds_tcp_connection *tc, *_tc;
@ -330,8 +341,10 @@ static void rds_tcp_destroy_conns(void)
/* avoid calling conn_destroy with irqs off */
spin_lock_irq(&rds_tcp_conn_lock);
list_splice(&rds_tcp_conn_list, &tmp_list);
INIT_LIST_HEAD(&rds_tcp_conn_list);
list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn))
list_move_tail(&tc->t_tcp_node, &tmp_list);
}
spin_unlock_irq(&rds_tcp_conn_lock);
list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node)
@ -491,10 +504,30 @@ static struct pernet_operations rds_tcp_net_ops = {
.size = sizeof(struct rds_tcp_net),
};
/* explicitly send a RST on each socket, thereby releasing any socket refcnts
* that may otherwise hold up netns deletion.
*/
static void rds_tcp_conn_paths_destroy(struct rds_connection *conn)
{
struct rds_conn_path *cp;
struct rds_tcp_connection *tc;
int i;
struct sock *sk;
for (i = 0; i < RDS_MPATH_WORKERS; i++) {
cp = &conn->c_path[i];
tc = cp->cp_transport_data;
if (!tc->t_sock)
continue;
sk = tc->t_sock->sk;
sk->sk_prot->disconnect(sk, 0);
tcp_done(sk);
}
}
static void rds_tcp_kill_sock(struct net *net)
{
struct rds_tcp_connection *tc, *_tc;
struct sock *sk;
LIST_HEAD(tmp_list);
struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
@ -507,13 +540,12 @@ static void rds_tcp_kill_sock(struct net *net)
if (net != c_net || !tc->t_sock)
continue;
list_move_tail(&tc->t_tcp_node, &tmp_list);
if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn))
list_move_tail(&tc->t_tcp_node, &tmp_list);
}
spin_unlock_irq(&rds_tcp_conn_lock);
list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node) {
sk = tc->t_sock->sk;
sk->sk_prot->disconnect(sk, 0);
tcp_done(sk);
rds_tcp_conn_paths_destroy(tc->t_cpath->cp_conn);
rds_conn_destroy(tc->t_cpath->cp_conn);
}
}