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.
> -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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