diff options
| author | Tung Nguyen <tung.q.nguyen@dektech.com.au> | 2019-02-25 06:57:20 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-03-10 09:17:18 +0300 |
| commit | ab04570d82b164daca4917c459c152dfb3839448 (patch) | |
| tree | c1ae0a752660708136d7272c221440859080da29 /net/tipc | |
| parent | 5fdb551fd6a6bda0010458fd34aa73d17e56c572 (diff) | |
| download | linux-ab04570d82b164daca4917c459c152dfb3839448.tar.xz | |
tipc: fix race condition causing hung sendto
[ Upstream commit bfd07f3dd4f111b884d7922b37eb239280f83d8c ]
When sending multicast messages via blocking socket,
if sending link is congested (tsk->cong_link_cnt is set to 1),
the sending thread will be put into sleeping state. However,
tipc_sk_filter_rcv() is called under socket spin lock but
tipc_wait_for_cond() is not. So, there is no guarantee that
the setting of tsk->cong_link_cnt to 0 in tipc_sk_proto_rcv() in
CPU-1 will be perceived by CPU-0. If that is the case, the sending
thread in CPU-0 after being waken up, will continue to see
tsk->cong_link_cnt as 1 and put the sending thread into sleeping
state again. The sending thread will sleep forever.
CPU-0 | CPU-1
tipc_wait_for_cond() |
{ |
// condition_ = !tsk->cong_link_cnt |
while ((rc_ = !(condition_))) { |
... |
release_sock(sk_); |
wait_woken(); |
| if (!sock_owned_by_user(sk))
| tipc_sk_filter_rcv()
| {
| ...
| tipc_sk_proto_rcv()
| {
| ...
| tsk->cong_link_cnt--;
| ...
| sk->sk_write_space(sk);
| ...
| }
| ...
| }
sched_annotate_sleep(); |
lock_sock(sk_); |
remove_wait_queue(); |
} |
} |
This commit fixes it by adding memory barrier to tipc_sk_proto_rcv()
and tipc_wait_for_cond().
Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: Tung Nguyen <tung.q.nguyen@dektech.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/tipc')
| -rw-r--r-- | net/tipc/socket.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/net/tipc/socket.c b/net/tipc/socket.c index c5614d8e74fa..88c307ef1318 100644 --- a/net/tipc/socket.c +++ b/net/tipc/socket.c @@ -377,11 +377,13 @@ static int tipc_sk_sock_err(struct socket *sock, long *timeout) #define tipc_wait_for_cond(sock_, timeo_, condition_) \ ({ \ + DEFINE_WAIT_FUNC(wait_, woken_wake_function); \ struct sock *sk_; \ int rc_; \ \ while ((rc_ = !(condition_))) { \ - DEFINE_WAIT_FUNC(wait_, woken_wake_function); \ + /* coupled with smp_wmb() in tipc_sk_proto_rcv() */ \ + smp_rmb(); \ sk_ = (sock_)->sk; \ rc_ = tipc_sk_sock_err((sock_), timeo_); \ if (rc_) \ @@ -1961,6 +1963,8 @@ static void tipc_sk_proto_rcv(struct sock *sk, return; case SOCK_WAKEUP: tipc_dest_del(&tsk->cong_links, msg_orignode(hdr), 0); + /* coupled with smp_rmb() in tipc_wait_for_cond() */ + smp_wmb(); tsk->cong_link_cnt--; wakeup = true; break; |