From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751936AbdKVW0H (ORCPT ); Wed, 22 Nov 2017 17:26:07 -0500 Received: from omzsmtpe02.verizonbusiness.com ([199.249.25.209]:38672 "EHLO omzsmtpe02.verizonbusiness.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752617AbdKVW0D (ORCPT ); Wed, 22 Nov 2017 17:26:03 -0500 From: alexander.levin@verizon.com Cc: Parthasarathy Bhuvaragan , "David S . Miller" , alexander.levin@verizon.com X-Host: pioneer.tdc.vzwcorp.com To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: [PATCH AUTOSEL for 4.9 38/54] tipc: fix nametbl_lock soft lockup at module exit Thread-Topic: [PATCH AUTOSEL for 4.9 38/54] tipc: fix nametbl_lock soft lockup at module exit Thread-Index: AQHTY+CYlE67AcbAUU2hiQXl1qSHoA== Date: Wed, 22 Nov 2017 22:24:00 +0000 Message-ID: <20171122222344.19782-38-alexander.levin@verizon.com> References: <20171122222344.19782-1-alexander.levin@verizon.com> In-Reply-To: <20171122222344.19782-1-alexander.levin@verizon.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.144.60.250] Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id vAMN8xtM000976 From: Parthasarathy Bhuvaragan [ Upstream commit 9dc3abdd1f7ea524e8552e0a3ef01219892ed1f4 ] Commit 333f796235a527 ("tipc: fix a race condition leading to subscriber refcnt bug") reveals a soft lockup while acquiring nametbl_lock. Before commit 333f796235a527, we call tipc_conn_shutdown() from tipc_close_conn() in the context of tipc_topsrv_stop(). In that context, we are allowed to grab the nametbl_lock. Commit 333f796235a527, moved tipc_conn_release (renamed from tipc_conn_shutdown) to the connection refcount cleanup. This allows either tipc_nametbl_withdraw() or tipc_topsrv_stop() to the cleanup. Since tipc_exit_net() first calls tipc_topsrv_stop() and then tipc_nametble_withdraw() increases the chances for the later to perform the connection cleanup. The soft lockup occurs in the call chain of tipc_nametbl_withdraw(), when it performs the tipc_conn_kref_release() as it tries to grab nametbl_lock again while holding it already. tipc_nametbl_withdraw() grabs nametbl_lock tipc_nametbl_remove_publ() tipc_subscrp_report_overlap() tipc_subscrp_send_event() tipc_conn_sendmsg() << if (con->flags != CF_CONNECTED) we do conn_put(), triggering the cleanup as refcount=0. >> tipc_conn_kref_release tipc_sock_release tipc_conn_release tipc_subscrb_delete tipc_subscrp_delete tipc_nametbl_unsubscribe << Soft Lockup >> The previous changes in this series fixes the race conditions fixed by commit 333f796235a527. Hence we can now revert the commit. Fixes: 333f796235a52727 ("tipc: fix a race condition leading to subscriber refcnt bug") Reported-and-Tested-by: John Thompson Acked-by: Ying Xue Acked-by: Jon Maloy Signed-off-by: Parthasarathy Bhuvaragan Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/tipc/server.c | 16 +++++----------- 1 file changed, 5 insertions(+), 11 deletions(-) diff --git a/net/tipc/server.c b/net/tipc/server.c index f89c0c2e8c16..04ff441b8065 100644 --- a/net/tipc/server.c +++ b/net/tipc/server.c @@ -86,7 +86,6 @@ struct outqueue_entry { static void tipc_recv_work(struct work_struct *work); static void tipc_send_work(struct work_struct *work); static void tipc_clean_outqueues(struct tipc_conn *con); -static void tipc_sock_release(struct tipc_conn *con); static void tipc_conn_kref_release(struct kref *kref) { @@ -104,7 +103,6 @@ static void tipc_conn_kref_release(struct kref *kref) } saddr->scope = -TIPC_NODE_SCOPE; kernel_bind(sock, (struct sockaddr *)saddr, sizeof(*saddr)); - tipc_sock_release(con); sock_release(sock); con->sock = NULL; @@ -194,19 +192,15 @@ static void tipc_unregister_callbacks(struct tipc_conn *con) write_unlock_bh(&sk->sk_callback_lock); } -static void tipc_sock_release(struct tipc_conn *con) +static void tipc_close_conn(struct tipc_conn *con) { struct tipc_server *s = con->server; - if (con->conid) - s->tipc_conn_release(con->conid, con->usr_data); - - tipc_unregister_callbacks(con); -} - -static void tipc_close_conn(struct tipc_conn *con) -{ if (test_and_clear_bit(CF_CONNECTED, &con->flags)) { + tipc_unregister_callbacks(con); + + if (con->conid) + s->tipc_conn_release(con->conid, con->usr_data); /* We shouldn't flush pending works as we may be in the * thread. In fact the races with pending rx/tx work structs -- 2.11.0