Wei Yongjun wrote:
>
> Vlad Yasevich wrote:
>> 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.
>>
>
> Not sure, but TCP does not call that function in user context at all.
It might as part of release_sock(). It call out to sk_backlog_rcv, which
calls tcp_v4_do_rcv() (the backlog handler). That handler will eventually
call tcp_data_queue() which will call sk_data_ready(). I don't see the code
paths that disable BH there.
-vlad
>
>> -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: [<c06aab60>] 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: [<cdfe363d>] sctp_sendmsg+0x23d/0xc00 [sctp]
>>>
>>> Signed-off-by: Wei Yongjun <yjwei@xxxxxxxxxxxxxx>
>>> ---
>>> 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)
>>> {
>>>
>>
>>
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