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authorSowmini Varadhan <sowmini.varadhan@oracle.com>2018-02-03 04:26:51 -0800
committerDavid S. Miller <davem@davemloft.net>2018-02-08 15:23:52 -0500
commitebeeb1ad9b8adcc37c2ec21a96f39e9d35199b46 (patch)
tree25c1f3a044ab1c8f8e15031f606b00ae35db2ed0 /net/rds/ib.c
parent79a8a642bf05cd0dced20621f6fef9d884124abd (diff)
rds: tcp: use rds_destroy_pending() to synchronize netns/module teardown and rds connection/workq management
An rds_connection can get added during netns deletion between lines 528 and 529 of 506 static void rds_tcp_kill_sock(struct net *net) : /* code to pull out all the rds_connections that should be destroyed */ : 528 spin_unlock_irq(&rds_tcp_conn_lock); 529 list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node) 530 rds_conn_destroy(tc->t_cpath->cp_conn); Such an rds_connection would miss out the rds_conn_destroy() loop (that cancels all pending work) and (if it was scheduled after netns deletion) could trigger the use-after-free. A similar race-window exists for the module unload path in rds_tcp_exit -> rds_tcp_destroy_conns Concurrency with netns deletion (rds_tcp_kill_sock()) must be handled by checking check_net() before enqueuing new work or adding new connections. Concurrency with module-unload is handled by maintaining a module specific flag that is set at the start of the module exit function, and must be checked before enqueuing new work or adding new connections. This commit refactors existing RDS_DESTROY_PENDING checks added by commit 3db6e0d172c9 ("rds: use RCU to synchronize work-enqueue with connection teardown") and consolidates all the concurrency checks listed above into the function rds_destroy_pending(). Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com> Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/rds/ib.c')
-rw-r--r--net/rds/ib.c17
1 files changed, 17 insertions, 0 deletions
diff --git a/net/rds/ib.c b/net/rds/ib.c
index ff0c98096af1..50a88f3e7e39 100644
--- a/net/rds/ib.c
+++ b/net/rds/ib.c
@@ -48,6 +48,7 @@
static unsigned int rds_ib_mr_1m_pool_size = RDS_MR_1M_POOL_SIZE;
static unsigned int rds_ib_mr_8k_pool_size = RDS_MR_8K_POOL_SIZE;
unsigned int rds_ib_retry_count = RDS_IB_DEFAULT_RETRY_COUNT;
+static atomic_t rds_ib_unloading;
module_param(rds_ib_mr_1m_pool_size, int, 0444);
MODULE_PARM_DESC(rds_ib_mr_1m_pool_size, " Max number of 1M mr per HCA");
@@ -378,8 +379,23 @@ static void rds_ib_unregister_client(void)
flush_workqueue(rds_wq);
}
+static void rds_ib_set_unloading(void)
+{
+ atomic_set(&rds_ib_unloading, 1);
+}
+
+static bool rds_ib_is_unloading(struct rds_connection *conn)
+{
+ struct rds_conn_path *cp = &conn->c_path[0];
+
+ return (test_bit(RDS_DESTROY_PENDING, &cp->cp_flags) ||
+ atomic_read(&rds_ib_unloading) != 0);
+}
+
void rds_ib_exit(void)
{
+ rds_ib_set_unloading();
+ synchronize_rcu();
rds_info_deregister_func(RDS_INFO_IB_CONNECTIONS, rds_ib_ic_info);
rds_ib_unregister_client();
rds_ib_destroy_nodev_conns();
@@ -413,6 +429,7 @@ struct rds_transport rds_ib_transport = {
.flush_mrs = rds_ib_flush_mrs,
.t_owner = THIS_MODULE,
.t_name = "infiniband",
+ .t_unloading = rds_ib_is_unloading,
.t_type = RDS_TRANS_IB
};