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| author | Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com> | 2017-01-24 13:00:46 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-01-24 16:14:58 -0500 |
| commit | 9dc3abdd1f7ea524e8552e0a3ef01219892ed1f4 (patch) | |
| tree | 5e8606b5a3c31d69a77e798c59d7f13bba6452fa /net/tipc | |
| parent | fc0adfc8fd18b61b6f7a3f28b429e134d6f3a008 (diff) | |
| download | linux-9dc3abdd1f7ea524e8552e0a3ef01219892ed1f4.tar.bz2 | |
tipc: fix nametbl_lock soft lockup at module exit
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 <thompa.atl@gmail.com>
Acked-by: Ying Xue <ying.xue@windriver.com>
Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tipc')
| -rw-r--r-- | net/tipc/server.c | 16 |
1 files changed, 5 insertions, 11 deletions
diff --git a/net/tipc/server.c b/net/tipc/server.c index 2e803601aa99..826cde2c401e 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 |