From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlad Yasevich Date: Wed, 03 Feb 2010 17:14:23 +0000 Subject: Re: [PATCH] sctp: avoid irq lock inversion while call sk->sk_data_ready() Message-Id: <4B69AEEF.3090103@hp.com> List-Id: References: <4B6903D6.8070106@cn.fujitsu.com> In-Reply-To: <4B6903D6.8070106@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-sctp@vger.kernel.org Wei Yongjun wrote: > sk->sk_data_ready() of sctp socket can be called from both BH and non-BH > contexts, but the default sk->sk_data_ready(), sock_def_readable(), can > not be used in this case. Therefore, we have to make a new function > sctp_data_ready() to grab sk->sk_data_ready() with BH disabling. > Wouldn't the same inversion happen in TCP as well? TCP can call that function in _bh and user contexts as well. -vlad > ============================> [ INFO: possible irq lock inversion dependency detected ] > 2.6.33-rc6 #129 > --------------------------------------------------------- > sctp_darn/1517 just changed the state of lock: > (clock-AF_INET){++.?..}, at: [] sock_def_readable+0x20/0x80 > but this lock took another, SOFTIRQ-unsafe lock in the past: > (slock-AF_INET){+.-...} > > and interrupts could create inverse lock ordering between them. > > other info that might help us debug this: > 1 lock held by sctp_darn/1517: > #0: (sk_lock-AF_INET){+.+.+.}, at: [] sctp_sendmsg+0x23d/0xc00 [sctp] > > Signed-off-by: Wei Yongjun > --- > include/net/sctp/sctp.h | 1 + > net/sctp/endpointola.c | 1 + > net/sctp/socket.c | 10 ++++++++++ > 3 files changed, 12 insertions(+), 0 deletions(-) > > diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h > index 78740ec..fa6cde5 100644 > --- a/include/net/sctp/sctp.h > +++ b/include/net/sctp/sctp.h > @@ -128,6 +128,7 @@ extern int sctp_register_pf(struct sctp_pf *, sa_family_t); > int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb); > int sctp_inet_listen(struct socket *sock, int backlog); > void sctp_write_space(struct sock *sk); > +void sctp_data_ready(struct sock *sk, int len); > unsigned int sctp_poll(struct file *file, struct socket *sock, > poll_table *wait); > void sctp_sock_rfree(struct sk_buff *skb); > diff --git a/net/sctp/endpointola.c b/net/sctp/endpointola.c > index 905fda5..7ec09ba 100644 > --- a/net/sctp/endpointola.c > +++ b/net/sctp/endpointola.c > @@ -144,6 +144,7 @@ static struct sctp_endpoint *sctp_endpoint_init(struct sctp_endpoint *ep, > /* Use SCTP specific send buffer space queues. */ > ep->sndbuf_policy = sctp_sndbuf_policy; > > + sk->sk_data_ready = sctp_data_ready; > sk->sk_write_space = sctp_write_space; > sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); > > diff --git a/net/sctp/socket.c b/net/sctp/socket.c > index 67fdac9..b437e2a 100644 > --- a/net/sctp/socket.c > +++ b/net/sctp/socket.c > @@ -6185,6 +6185,16 @@ do_nonblock: > goto out; > } > > +void sctp_data_ready(struct sock *sk, int len) > +{ > + read_lock_bh(&sk->sk_callback_lock); > + if (sk_has_sleeper(sk)) > + wake_up_interruptible_sync_poll(sk->sk_sleep, POLLIN | > + POLLRDNORM | POLLRDBAND); > + sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN); > + read_unlock_bh(&sk->sk_callback_lock); > +} > + > /* If socket sndbuf has changed, wake up all per association waiters. */ > void sctp_write_space(struct sock *sk) > {