| Message ID | 1ff9487ec87d1ca5cbd32ea40b079099bfeedc06.1622569473.git.pabeni@redhat.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Commit | 9f1527adae818bba442adcc3301e1469e616d6ee |
| Delegated to: | Paolo Abeni |
| Headers | show |
| Series | [v2,mptcp-net] mptcp: fix soft lookup in subflow_error_report(). | expand |
On Tue, 1 Jun 2021, Paolo Abeni wrote: > Maxim reported a soft lookup in subflow_error_report(): > > watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:0] > RIP: 0010:native_queued_spin_lock_slowpath > RSP: 0018:ffffa859c0003bc0 EFLAGS: 00000202 > RAX: 0000000000000101 RBX: 0000000000000001 RCX: 0000000000000000 > RDX: ffff9195c2772d88 RSI: 0000000000000000 RDI: ffff9195c2772d88 > RBP: ffff9195c2772d00 R08: 00000000000067b0 R09: c6e31da9eb1e44f4 > R10: ffff9195ef379700 R11: ffff9195edb50710 R12: ffff9195c2772d88 > R13: ffff9195f500e3d0 R14: ffff9195ef379700 R15: ffff9195ef379700 > FS: 0000000000000000(0000) GS:ffff91961f400000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 000000c000407000 CR3: 0000000002988000 CR4: 00000000000006f0 > Call Trace: > <IRQ> > _raw_spin_lock_bh > subflow_error_report > mptcp_subflow_data_available > __mptcp_move_skbs_from_subflow > mptcp_data_ready > tcp_data_queue > tcp_rcv_established > tcp_v4_do_rcv > tcp_v4_rcv > ip_protocol_deliver_rcu > ip_local_deliver_finish > __netif_receive_skb_one_core > netif_receive_skb > rtl8139_poll 8139too > __napi_poll > net_rx_action > __do_softirq > __irq_exit_rcu > common_interrupt > </IRQ> > > The calling function - mptcp_subflow_data_available() - can be invoked > from different contexts: > - plain ssk socket lock > - ssk socket lock + mptcp_data_lock > - ssk socket lock + mptcp_data_lock + msk socket lock. > > Since subflow_error_report() tries to acquire the mptcp_data_lock, the > latter two call chains will cause soft lookup. > > This change addresses the issue moving the error reporting call to > outer functions, where the held locks list is known and the we can > acquire only the needed one. > > Reported-by: Maxim Galaganov <max@internet.ru> > Fixes: 15cc10453398 ("mptcp: deliver ssk errors to msk") > Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/199 > Signed-off-by: Paolo Abeni <pabeni@redhat.com> > --- > v1 -> v2: > - added missing unlikely() annotation > > Note: the diffstat is lager than expected because I had to move > some functions upwards. Could be reduced [ab-]using forward declaration. > --- > net/mptcp/protocol.c | 9 ++++++ > net/mptcp/subflow.c | 75 +++++++++++++++++++++++--------------------- > 2 files changed, 48 insertions(+), 36 deletions(-) > ... > diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c > index 6b1cd4257edf..c4ca37dd4be2 100644 > --- a/net/mptcp/subflow.c > +++ b/net/mptcp/subflow.c ... > @@ -1293,6 +1257,43 @@ static void subflow_error_report(struct sock *ssk) > mptcp_data_unlock(sk); > } > > +static void subflow_data_ready(struct sock *sk) > +{ > + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); > + u16 state = 1 << inet_sk_state_load(sk); > + struct sock *parent = subflow->conn; > + struct mptcp_sock *msk; > + > + msk = mptcp_sk(parent); > + if (state & TCPF_LISTEN) { > + /* MPJ subflow are removed from accept queue before reaching here, > + * avoid stray wakeups > + */ > + if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue)) > + return; > + > + set_bit(MPTCP_DATA_READY, &msk->flags); > + parent->sk_data_ready(parent); > + return; > + } > + > + WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable && > + !subflow->mp_join && !(state & TCPF_CLOSE)); > + > + if (mptcp_subflow_data_available(sk)) > + mptcp_data_ready(parent, sk); > + else if (unlikely(sk->sk_err)) > + subflow_error_report(sk); I was wondering if the 'else if' was the way to go here, but then I saw that if there are errors encountered down the mptcp_data_ready() execution path, those will get reported before mptcp_data_ready() returns. So the patch looks good to me. Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com> > +} > + > +static void subflow_write_space(struct sock *ssk) > +{ > + struct sock *sk = mptcp_subflow_ctx(ssk)->conn; > + > + mptcp_propagate_sndbuf(sk, ssk); > + mptcp_write_space(sk); > +} > + > static struct inet_connection_sock_af_ops * > subflow_default_af_ops(struct sock *sk) > { -- Mat Martineau Intel
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 44fd8c8c759b..4c0232067bf3 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -689,6 +689,12 @@ static void move_skbs_to_msk(struct mptcp_sock *msk, struct sock *ssk) __mptcp_move_skbs_from_subflow(msk, ssk, &moved); __mptcp_ofo_queue(msk); + if (unlikely(ssk->sk_err)) { + if (!sock_owned_by_user(sk)) + __mptcp_error_report(sk); + else + set_bit(MPTCP_ERROR_REPORT, &msk->flags); + } /* If the moves have caught up with the DATA_FIN sequence number * it's time to ack the DATA_FIN and change socket state, but @@ -1987,6 +1993,9 @@ static bool __mptcp_move_skbs(struct mptcp_sock *msk) done = __mptcp_move_skbs_from_subflow(msk, ssk, &moved); mptcp_data_unlock(sk); tcp_cleanup_rbuf(ssk, moved); + + if (unlikely(ssk->sk_err)) + __mptcp_error_report(sk); unlock_sock_fast(ssk, slowpath); } while (!done); diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 6b1cd4257edf..c4ca37dd4be2 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -1163,7 +1163,6 @@ static bool subflow_check_data_avail(struct sock *ssk) * subflow_error_report() will introduce the appropriate barriers */ ssk->sk_err = EBADMSG; - ssk->sk_error_report(ssk); tcp_set_state(ssk, TCP_CLOSE); subflow->reset_transient = 0; subflow->reset_reason = MPTCP_RST_EMPTCP; @@ -1218,41 +1217,6 @@ void mptcp_space(const struct sock *ssk, int *space, int *full_space) *full_space = tcp_full_space(sk); } -static void subflow_data_ready(struct sock *sk) -{ - struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); - u16 state = 1 << inet_sk_state_load(sk); - struct sock *parent = subflow->conn; - struct mptcp_sock *msk; - - msk = mptcp_sk(parent); - if (state & TCPF_LISTEN) { - /* MPJ subflow are removed from accept queue before reaching here, - * avoid stray wakeups - */ - if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue)) - return; - - set_bit(MPTCP_DATA_READY, &msk->flags); - parent->sk_data_ready(parent); - return; - } - - WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable && - !subflow->mp_join && !(state & TCPF_CLOSE)); - - if (mptcp_subflow_data_available(sk)) - mptcp_data_ready(parent, sk); -} - -static void subflow_write_space(struct sock *ssk) -{ - struct sock *sk = mptcp_subflow_ctx(ssk)->conn; - - mptcp_propagate_sndbuf(sk, ssk); - mptcp_write_space(sk); -} - void __mptcp_error_report(struct sock *sk) { struct mptcp_subflow_context *subflow; @@ -1293,6 +1257,43 @@ static void subflow_error_report(struct sock *ssk) mptcp_data_unlock(sk); } +static void subflow_data_ready(struct sock *sk) +{ + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); + u16 state = 1 << inet_sk_state_load(sk); + struct sock *parent = subflow->conn; + struct mptcp_sock *msk; + + msk = mptcp_sk(parent); + if (state & TCPF_LISTEN) { + /* MPJ subflow are removed from accept queue before reaching here, + * avoid stray wakeups + */ + if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue)) + return; + + set_bit(MPTCP_DATA_READY, &msk->flags); + parent->sk_data_ready(parent); + return; + } + + WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable && + !subflow->mp_join && !(state & TCPF_CLOSE)); + + if (mptcp_subflow_data_available(sk)) + mptcp_data_ready(parent, sk); + else if (unlikely(sk->sk_err)) + subflow_error_report(sk); +} + +static void subflow_write_space(struct sock *ssk) +{ + struct sock *sk = mptcp_subflow_ctx(ssk)->conn; + + mptcp_propagate_sndbuf(sk, ssk); + mptcp_write_space(sk); +} + static struct inet_connection_sock_af_ops * subflow_default_af_ops(struct sock *sk) { @@ -1603,6 +1604,8 @@ static void subflow_state_change(struct sock *sk) */ if (mptcp_subflow_data_available(sk)) mptcp_data_ready(parent, sk); + else if (sk->sk_err) + subflow_error_report(sk); subflow_sched_work_if_closed(mptcp_sk(parent), sk);
Maxim reported a soft lookup in subflow_error_report(): watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:0] RIP: 0010:native_queued_spin_lock_slowpath RSP: 0018:ffffa859c0003bc0 EFLAGS: 00000202 RAX: 0000000000000101 RBX: 0000000000000001 RCX: 0000000000000000 RDX: ffff9195c2772d88 RSI: 0000000000000000 RDI: ffff9195c2772d88 RBP: ffff9195c2772d00 R08: 00000000000067b0 R09: c6e31da9eb1e44f4 R10: ffff9195ef379700 R11: ffff9195edb50710 R12: ffff9195c2772d88 R13: ffff9195f500e3d0 R14: ffff9195ef379700 R15: ffff9195ef379700 FS: 0000000000000000(0000) GS:ffff91961f400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c000407000 CR3: 0000000002988000 CR4: 00000000000006f0 Call Trace: <IRQ> _raw_spin_lock_bh subflow_error_report mptcp_subflow_data_available __mptcp_move_skbs_from_subflow mptcp_data_ready tcp_data_queue tcp_rcv_established tcp_v4_do_rcv tcp_v4_rcv ip_protocol_deliver_rcu ip_local_deliver_finish __netif_receive_skb_one_core netif_receive_skb rtl8139_poll 8139too __napi_poll net_rx_action __do_softirq __irq_exit_rcu common_interrupt </IRQ> The calling function - mptcp_subflow_data_available() - can be invoked from different contexts: - plain ssk socket lock - ssk socket lock + mptcp_data_lock - ssk socket lock + mptcp_data_lock + msk socket lock. Since subflow_error_report() tries to acquire the mptcp_data_lock, the latter two call chains will cause soft lookup. This change addresses the issue moving the error reporting call to outer functions, where the held locks list is known and the we can acquire only the needed one. Reported-by: Maxim Galaganov <max@internet.ru> Fixes: 15cc10453398 ("mptcp: deliver ssk errors to msk") Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/199 Signed-off-by: Paolo Abeni <pabeni@redhat.com> --- v1 -> v2: - added missing unlikely() annotation Note: the diffstat is lager than expected because I had to move some functions upwards. Could be reduced [ab-]using forward declaration. --- net/mptcp/protocol.c | 9 ++++++ net/mptcp/subflow.c | 75 +++++++++++++++++++++++--------------------- 2 files changed, 48 insertions(+), 36 deletions(-)