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Message-Id: <12028a7fa6a29310dc3a74ff398a6784769da852.1515068006.git.sowmini.varadhan@oracle.com>
Date: Thu, 4 Jan 2018 06:53:00 -0800
From: Sowmini Varadhan <sowmini.varadhan@...cle.com>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net, rds-devel@....oracle.com,
sowmini.varadhan@...cle.com, santosh.shilimkar@...cle.com
Subject: [PATCH net-next 2/2] rds: use RCU to synchronize work-enqueue with connection teardown
rds_sendmsg() can enqueue work on cp_send_w from process context, but
it should not enqueue this work if connection teardown has commenced
(else we risk enquing work after rds_conn_path_destroy() has assumed that
all work has been cancelled/flushed).
Similarly some other functions like rds_cong_queue_updates
and rds_tcp_data_ready are called in softirq context, and may end
up enqueuing work on rds_wq after rds_conn_path_destroy() has assumed
that all workqs are quiesced.
Check the RDS_DESTROY_PENDING bit and use rcu synchronization to avoid
all these races.
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@...cle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@...cle.com>
---
net/rds/cong.c | 10 +++++++---
net/rds/connection.c | 21 +++++++++++++++++----
net/rds/send.c | 37 ++++++++++++++++++++++++++++++++-----
net/rds/tcp_recv.c | 8 ++++++--
net/rds/tcp_send.c | 5 ++++-
net/rds/threads.c | 20 +++++++++++++++-----
6 files changed, 81 insertions(+), 20 deletions(-)
diff --git a/net/rds/cong.c b/net/rds/cong.c
index 8398fee..8d19fd2 100644
--- a/net/rds/cong.c
+++ b/net/rds/cong.c
@@ -219,7 +219,11 @@ void rds_cong_queue_updates(struct rds_cong_map *map)
spin_lock_irqsave(&rds_cong_lock, flags);
list_for_each_entry(conn, &map->m_conn_list, c_map_item) {
- if (!test_and_set_bit(0, &conn->c_map_queued)) {
+ struct rds_conn_path *cp = &conn->c_path[0];
+
+ rcu_read_lock();
+ if (!test_and_set_bit(0, &conn->c_map_queued) &&
+ !test_bit(RDS_DESTROY_PENDING, &cp->cp_flags)) {
rds_stats_inc(s_cong_update_queued);
/* We cannot inline the call to rds_send_xmit() here
* for two reasons (both pertaining to a TCP transport):
@@ -235,9 +239,9 @@ void rds_cong_queue_updates(struct rds_cong_map *map)
* therefore trigger warnings.
* Defer the xmit to rds_send_worker() instead.
*/
- queue_delayed_work(rds_wq,
- &conn->c_path[0].cp_send_w, 0);
+ queue_delayed_work(rds_wq, &cp->cp_send_w, 0);
}
+ rcu_read_unlock();
}
spin_unlock_irqrestore(&rds_cong_lock, flags);
diff --git a/net/rds/connection.c b/net/rds/connection.c
index 1eed197..b10c0ef 100644
--- a/net/rds/connection.c
+++ b/net/rds/connection.c
@@ -366,8 +366,6 @@ void rds_conn_shutdown(struct rds_conn_path *cp)
* to the conn hash, so we never trigger a reconnect on this
* conn - the reconnect is always triggered by the active peer. */
cancel_delayed_work_sync(&cp->cp_conn_w);
- if (test_bit(RDS_DESTROY_PENDING, &cp->cp_flags))
- return;
rcu_read_lock();
if (!hlist_unhashed(&conn->c_hash_node)) {
rcu_read_unlock();
@@ -390,6 +388,7 @@ static void rds_conn_path_destroy(struct rds_conn_path *cp)
return;
/* make sure lingering queued work won't try to ref the conn */
+ synchronize_rcu();
cancel_delayed_work_sync(&cp->cp_send_w);
cancel_delayed_work_sync(&cp->cp_recv_w);
@@ -407,6 +406,11 @@ static void rds_conn_path_destroy(struct rds_conn_path *cp)
if (cp->cp_xmit_rm)
rds_message_put(cp->cp_xmit_rm);
+ WARN_ON(delayed_work_pending(&cp->cp_send_w));
+ WARN_ON(delayed_work_pending(&cp->cp_recv_w));
+ WARN_ON(delayed_work_pending(&cp->cp_conn_w));
+ WARN_ON(work_pending(&cp->cp_down_w));
+
cp->cp_conn->c_trans->conn_free(cp->cp_transport_data);
}
@@ -686,10 +690,13 @@ void rds_conn_path_drop(struct rds_conn_path *cp, bool destroy)
{
atomic_set(&cp->cp_state, RDS_CONN_ERROR);
- if (!destroy && test_bit(RDS_DESTROY_PENDING, &cp->cp_flags))
+ rcu_read_lock();
+ if (!destroy && test_bit(RDS_DESTROY_PENDING, &cp->cp_flags)) {
+ rcu_read_unlock();
return;
-
+ }
queue_work(rds_wq, &cp->cp_down_w);
+ rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(rds_conn_path_drop);
@@ -706,9 +713,15 @@ void rds_conn_drop(struct rds_connection *conn)
*/
void rds_conn_path_connect_if_down(struct rds_conn_path *cp)
{
+ rcu_read_lock();
+ if (test_bit(RDS_DESTROY_PENDING, &cp->cp_flags)) {
+ rcu_read_unlock();
+ return;
+ }
if (rds_conn_path_state(cp) == RDS_CONN_DOWN &&
!test_and_set_bit(RDS_RECONNECT_PENDING, &cp->cp_flags))
queue_delayed_work(rds_wq, &cp->cp_conn_w, 0);
+ rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(rds_conn_path_connect_if_down);
diff --git a/net/rds/send.c b/net/rds/send.c
index f72466c..d3e32d1 100644
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -162,6 +162,12 @@ int rds_send_xmit(struct rds_conn_path *cp)
goto out;
}
+ if (test_bit(RDS_DESTROY_PENDING, &cp->cp_flags)) {
+ release_in_xmit(cp);
+ ret = -ENETUNREACH; /* dont requeue send work */
+ goto out;
+ }
+
/*
* we record the send generation after doing the xmit acquire.
* if someone else manages to jump in and do some work, we'll use
@@ -437,7 +443,12 @@ int rds_send_xmit(struct rds_conn_path *cp)
!list_empty(&cp->cp_send_queue)) && !raced) {
if (batch_count < send_batch_count)
goto restart;
- queue_delayed_work(rds_wq, &cp->cp_send_w, 1);
+ rcu_read_lock();
+ if (test_bit(RDS_DESTROY_PENDING, &cp->cp_flags))
+ ret = -ENETUNREACH;
+ else
+ queue_delayed_work(rds_wq, &cp->cp_send_w, 1);
+ rcu_read_unlock();
} else if (raced) {
rds_stats_inc(s_send_lock_queue_raced);
}
@@ -1151,6 +1162,11 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
else
cpath = &conn->c_path[0];
+ if (test_bit(RDS_DESTROY_PENDING, &cpath->cp_flags)) {
+ ret = -EAGAIN;
+ goto out;
+ }
+
rds_conn_path_connect_if_down(cpath);
ret = rds_cong_wait(conn->c_fcong, dport, nonblock, rs);
@@ -1190,9 +1206,17 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
rds_stats_inc(s_send_queued);
ret = rds_send_xmit(cpath);
- if (ret == -ENOMEM || ret == -EAGAIN)
- queue_delayed_work(rds_wq, &cpath->cp_send_w, 1);
-
+ if (ret == -ENOMEM || ret == -EAGAIN) {
+ ret = 0;
+ rcu_read_lock();
+ if (test_bit(RDS_DESTROY_PENDING, &cpath->cp_flags))
+ ret = -ENETUNREACH;
+ else
+ queue_delayed_work(rds_wq, &cpath->cp_send_w, 1);
+ rcu_read_unlock();
+ }
+ if (ret)
+ goto out;
rds_message_put(rm);
return payload_len;
@@ -1270,7 +1294,10 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
rds_stats_inc(s_send_pong);
/* schedule the send work on rds_wq */
- queue_delayed_work(rds_wq, &cp->cp_send_w, 1);
+ rcu_read_lock();
+ if (!test_bit(RDS_DESTROY_PENDING, &cp->cp_flags))
+ queue_delayed_work(rds_wq, &cp->cp_send_w, 1);
+ rcu_read_unlock();
rds_message_put(rm);
return 0;
diff --git a/net/rds/tcp_recv.c b/net/rds/tcp_recv.c
index e006ef8..dd707b9 100644
--- a/net/rds/tcp_recv.c
+++ b/net/rds/tcp_recv.c
@@ -321,8 +321,12 @@ void rds_tcp_data_ready(struct sock *sk)
ready = tc->t_orig_data_ready;
rds_tcp_stats_inc(s_tcp_data_ready_calls);
- if (rds_tcp_read_sock(cp, GFP_ATOMIC) == -ENOMEM)
- queue_delayed_work(rds_wq, &cp->cp_recv_w, 0);
+ if (rds_tcp_read_sock(cp, GFP_ATOMIC) == -ENOMEM) {
+ rcu_read_lock();
+ if (!test_bit(RDS_DESTROY_PENDING, &cp->cp_flags))
+ queue_delayed_work(rds_wq, &cp->cp_recv_w, 0);
+ rcu_read_unlock();
+ }
out:
read_unlock_bh(&sk->sk_callback_lock);
ready(sk);
diff --git a/net/rds/tcp_send.c b/net/rds/tcp_send.c
index dc860d1..73c7476 100644
--- a/net/rds/tcp_send.c
+++ b/net/rds/tcp_send.c
@@ -202,8 +202,11 @@ void rds_tcp_write_space(struct sock *sk)
tc->t_last_seen_una = rds_tcp_snd_una(tc);
rds_send_path_drop_acked(cp, rds_tcp_snd_una(tc), rds_tcp_is_acked);
- if ((refcount_read(&sk->sk_wmem_alloc) << 1) <= sk->sk_sndbuf)
+ rcu_read_lock();
+ if ((refcount_read(&sk->sk_wmem_alloc) << 1) <= sk->sk_sndbuf &&
+ !test_bit(RDS_DESTROY_PENDING, &cp->cp_flags))
queue_delayed_work(rds_wq, &cp->cp_send_w, 0);
+ rcu_read_unlock();
out:
read_unlock_bh(&sk->sk_callback_lock);
diff --git a/net/rds/threads.c b/net/rds/threads.c
index f121daa..eb76db1 100644
--- a/net/rds/threads.c
+++ b/net/rds/threads.c
@@ -87,8 +87,12 @@ void rds_connect_path_complete(struct rds_conn_path *cp, int curr)
cp->cp_reconnect_jiffies = 0;
set_bit(0, &cp->cp_conn->c_map_queued);
- queue_delayed_work(rds_wq, &cp->cp_send_w, 0);
- queue_delayed_work(rds_wq, &cp->cp_recv_w, 0);
+ rcu_read_lock();
+ if (!test_bit(RDS_DESTROY_PENDING, &cp->cp_flags)) {
+ queue_delayed_work(rds_wq, &cp->cp_send_w, 0);
+ queue_delayed_work(rds_wq, &cp->cp_recv_w, 0);
+ }
+ rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(rds_connect_path_complete);
@@ -133,7 +137,10 @@ void rds_queue_reconnect(struct rds_conn_path *cp)
set_bit(RDS_RECONNECT_PENDING, &cp->cp_flags);
if (cp->cp_reconnect_jiffies == 0) {
cp->cp_reconnect_jiffies = rds_sysctl_reconnect_min_jiffies;
- queue_delayed_work(rds_wq, &cp->cp_conn_w, 0);
+ rcu_read_lock();
+ if (!test_bit(RDS_DESTROY_PENDING, &cp->cp_flags))
+ queue_delayed_work(rds_wq, &cp->cp_conn_w, 0);
+ rcu_read_unlock();
return;
}
@@ -141,8 +148,11 @@ void rds_queue_reconnect(struct rds_conn_path *cp)
rdsdebug("%lu delay %lu ceil conn %p for %pI4 -> %pI4\n",
rand % cp->cp_reconnect_jiffies, cp->cp_reconnect_jiffies,
conn, &conn->c_laddr, &conn->c_faddr);
- queue_delayed_work(rds_wq, &cp->cp_conn_w,
- rand % cp->cp_reconnect_jiffies);
+ rcu_read_lock();
+ if (!test_bit(RDS_DESTROY_PENDING, &cp->cp_flags))
+ queue_delayed_work(rds_wq, &cp->cp_conn_w,
+ rand % cp->cp_reconnect_jiffies);
+ rcu_read_unlock();
cp->cp_reconnect_jiffies = min(cp->cp_reconnect_jiffies * 2,
rds_sysctl_reconnect_max_jiffies);
--
1.7.1
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