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net/smc: no socket state changes in tasklet context 

Several state changes occur during SMC socket closing. Currently
state changes triggered locally occur in process context with
lock_sock() taken while state changes triggered by peer occur in
tasklet context with bh_lock_sock() taken. bh_lock_sock() does not
wait till a lock_sock(() task in process context is finished. This
may lead to races in socket state transitions resulting in dangling
SMC-sockets, or it may lead to duplicate SMC socket freeing.
This patch introduces a closing worker to run all state changes under
lock_sock().

Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Reviewed-by: Thomas Richter <tmricht@linux.vnet.ibm.com>
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ursula Braun 2017-04-10 14:58:01 +02:00 committed by David S. Miller
parent 90e9517ed9
commit 46c28dbd4c
6 changed files with 41 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
net/smc/af_smc.c
View File

@ -451,6 +451,9 @@ static int smc_connect_rdma(struct smc_sock *smc)
goto decline_rdma_unlock;
}
smc_close_init(smc);
smc_rx_init(smc);
if (local_contact == SMC_FIRST_CONTACT) {
rc = smc_ib_ready_link(link);
if (rc) {
@ -477,7 +480,6 @@ static int smc_connect_rdma(struct smc_sock *smc)
mutex_unlock(&smc_create_lgr_pending);
smc_tx_init(smc);
smc_rx_init(smc);
out_connected:
smc_copy_sock_settings_to_clc(smc);
@ -800,6 +802,9 @@ static void smc_listen_work(struct work_struct *work)
goto decline_rdma;
}
smc_close_init(new_smc);
smc_rx_init(new_smc);
rc = smc_clc_send_accept(new_smc, local_contact);
if (rc)
goto out_err;
@ -839,7 +844,6 @@ static void smc_listen_work(struct work_struct *work)
}
smc_tx_init(new_smc);
smc_rx_init(new_smc);
out_connected:
sk_refcnt_debug_inc(newsmcsk);

1
net/smc/smc.h
View File

@ -164,6 +164,7 @@ struct smc_connection {
#ifndef KERNEL_HAS_ATOMIC64
spinlock_t acurs_lock; /* protect cursors */
#endif
struct work_struct close_work; /* peer sent some closing */
};
struct smc_sock { /* smc sock container */

9
net/smc/smc_cdc.c
View File

@ -217,8 +217,13 @@ static void smc_cdc_msg_recv_action(struct smc_sock *smc,
smc->sk.sk_err = ECONNRESET;
conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
}
if (smc_cdc_rxed_any_close_or_senddone(conn))
smc_close_passive_received(smc);
if (smc_cdc_rxed_any_close_or_senddone(conn)) {
smc->sk.sk_shutdown |= RCV_SHUTDOWN;
if (smc->clcsock && smc->clcsock->sk)
smc->clcsock->sk->sk_shutdown |= RCV_SHUTDOWN;
sock_set_flag(&smc->sk, SOCK_DONE);
schedule_work(&conn->close_work);
}
/* piggy backed tx info */
/* trigger sndbuf consumer: RDMA write into peer RMBE and CDC */

39
net/smc/smc_close.c
View File

@ -117,7 +117,6 @@ void smc_close_active_abort(struct smc_sock *smc)
struct smc_cdc_conn_state_flags *txflags =
&smc->conn.local_tx_ctrl.conn_state_flags;
bh_lock_sock(&smc->sk);
smc->sk.sk_err = ECONNABORTED;
if (smc->clcsock && smc->clcsock->sk) {
smc->clcsock->sk->sk_err = ECONNABORTED;
@ -125,6 +124,7 @@ void smc_close_active_abort(struct smc_sock *smc)
}
switch (smc->sk.sk_state) {
case SMC_INIT:
case SMC_ACTIVE:
smc->sk.sk_state = SMC_PEERABORTWAIT;
break;
case SMC_APPCLOSEWAIT1:
@ -161,7 +161,6 @@ void smc_close_active_abort(struct smc_sock *smc)
}
sock_set_flag(&smc->sk, SOCK_DEAD);
bh_unlock_sock(&smc->sk);
smc->sk.sk_state_change(&smc->sk);
}
@ -185,7 +184,7 @@ again:
case SMC_INIT:
sk->sk_state = SMC_CLOSED;
if (smc->smc_listen_work.func)
flush_work(&smc->smc_listen_work);
cancel_work_sync(&smc->smc_listen_work);
sock_put(sk);
break;
case SMC_LISTEN:
@ -198,7 +197,7 @@ again:
}
release_sock(sk);
smc_close_cleanup_listen(sk);
flush_work(&smc->tcp_listen_work);
cancel_work_sync(&smc->smc_listen_work);
lock_sock(sk);
break;
case SMC_ACTIVE:
@ -306,22 +305,27 @@ static void smc_close_passive_abort_received(struct smc_sock *smc)
/* Some kind of closing has been received: peer_conn_closed, peer_conn_abort,
* or peer_done_writing.
* Called under tasklet context.
*/
void smc_close_passive_received(struct smc_sock *smc)
static void smc_close_passive_work(struct work_struct *work)
{
struct smc_cdc_conn_state_flags *rxflags =
&smc->conn.local_rx_ctrl.conn_state_flags;
struct smc_connection *conn = container_of(work,
struct smc_connection,
close_work);
struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
struct smc_cdc_conn_state_flags *rxflags;
struct sock *sk = &smc->sk;
int old_state;
sk->sk_shutdown |= RCV_SHUTDOWN;
if (smc->clcsock && smc->clcsock->sk)
smc->clcsock->sk->sk_shutdown |= RCV_SHUTDOWN;
sock_set_flag(&smc->sk, SOCK_DONE);
lock_sock(&smc->sk);
old_state = sk->sk_state;
if (!conn->alert_token_local) {
/* abnormal termination */
smc_close_active_abort(smc);
goto wakeup;
}
rxflags = &smc->conn.local_rx_ctrl.conn_state_flags;
if (rxflags->peer_conn_abort) {
smc_close_passive_abort_received(smc);
goto wakeup;
@ -373,11 +377,12 @@ wakeup:
sk->sk_write_space(sk); /* wakeup blocked sndbuf producers */
if ((sk->sk_state == SMC_CLOSED) &&
(sock_flag(sk, SOCK_DEAD) || (old_state == SMC_INIT))) {
(sock_flag(sk, SOCK_DEAD) || !sk->sk_socket)) {
smc_conn_free(&smc->conn);
schedule_delayed_work(&smc->sock_put_work,
SMC_CLOSE_SOCK_PUT_DELAY);
}
release_sock(&smc->sk);
}
void smc_close_sock_put_work(struct work_struct *work)
@ -442,3 +447,9 @@ again:
sk->sk_state_change(&smc->sk);
return rc;
}
/* Initialize close properties on connection establishment. */
void smc_close_init(struct smc_sock *smc)
{
INIT_WORK(&smc->conn.close_work, smc_close_passive_work);
}

2
net/smc/smc_close.h
View File

@ -21,8 +21,8 @@
void smc_close_wake_tx_prepared(struct smc_sock *smc);
void smc_close_active_abort(struct smc_sock *smc);
int smc_close_active(struct smc_sock *smc);
void smc_close_passive_received(struct smc_sock *smc);
void smc_close_sock_put_work(struct work_struct *work);
int smc_close_shutdown_write(struct smc_sock *smc);
void smc_close_init(struct smc_sock *smc);
#endif /* SMC_CLOSE_H */

2
net/smc/smc_core.c
View File

@ -316,7 +316,7 @@ void smc_lgr_terminate(struct smc_link_group *lgr)
smc = container_of(conn, struct smc_sock, conn);
sock_hold(&smc->sk);
__smc_lgr_unregister_conn(conn);
smc_close_active_abort(smc);
schedule_work(&conn->close_work);
sock_put(&smc->sk);
node = rb_first(&lgr->conns_all);
}