>
> Wei Yongjun wrote:
>
>> It should be possible to send a message and set the SCTP_EOF flag
>> at the same time, but we don't support it yet. This patch fix the
>> sendmsg() flag SCTP_EOF to comply to spec.
>>
>> Signed-off-by: Wei Yongjun <yjwei@xxxxxxxxxxxxxx>
>> ---
>> V2 -> V3:
>> - return -EWOULDBLOCK in non-blocking limitation case
>> - allow SCTP_EOF in CLOSED state
>> ---
>> net/sctp/socket.c | 39 +++++++++++++++++++++++++++++++--------
>> 1 files changed, 31 insertions(+), 8 deletions(-)
>>
>> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
>> index 0af3a8c..fcd8128 100644
>> --- a/net/sctp/socket.c
>> +++ b/net/sctp/socket.c
>> @@ -1555,13 +1555,11 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
>> goto out_nounlock;
>> }
>>
>> - /* If SCTP_EOF is set, no data can be sent. Disallow sending zero
>> - * length messages when SCTP_EOF|SCTP_ABORT is not set.
>> - * If SCTP_ABORT is set, the message length could be non zero with
>> - * the msg_iov set to the user abort reason.
>> + /* Disallow sending zero length messages when SCTP_EOF|SCTP_ABORT
>> + * is not set. If SCTP_ABORT is set, the message length could be
>> + * non zero with the msg_iov set to the user abort reason.
>> */
>> - if (((sinfo_flags & SCTP_EOF) && (msg_len > 0)) ||
>> - (!(sinfo_flags & (SCTP_EOF|SCTP_ABORT)) && (msg_len == 0))) {
>> + if (!(sinfo_flags & (SCTP_EOF|SCTP_ABORT)) && (msg_len == 0)) {
>> err = -EINVAL;
>> goto out_nounlock;
>> }
>> @@ -1618,13 +1616,24 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
>> goto out_unlock;
>> }
>>
>> - if (sinfo_flags & SCTP_EOF) {
>> + /* Forbid SCTP_EOF and send a message combination
>> + * on non-blocking sockets.
>> + */
>> + if ((sinfo_flags & SCTP_EOF) && msg_len != 0 &&
>> + sk->sk_socket->file &&
>> + (sk->sk_socket->file->f_flags & O_NONBLOCK)) {
>> + err = -EWOULDBLOCK;
>> + goto out_nounlock;
>> + }
>> +
>> + if (sinfo_flags & SCTP_EOF && msg_len == 0) {
>> SCTP_DEBUG_PRINTK("Shutting down association: %p\n",
>> asoc);
>> sctp_primitive_SHUTDOWN(asoc, NULL);
>> err = 0;
>> goto out_unlock;
>> }
>> +
>> if (sinfo_flags & SCTP_ABORT) {
>>
>> chunk = sctp_make_abort_user(asoc, msg, msg_len);
>> @@ -1644,7 +1653,7 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
>> if (!asoc) {
>> SCTP_DEBUG_PRINTK("There is no association yet.\n");
>>
>> - if (sinfo_flags & (SCTP_EOF | SCTP_ABORT)) {
>> + if (sinfo_flags & SCTP_ABORT) {
>> err = -EINVAL;
>> goto out_unlock;
>> }
>> @@ -1850,6 +1859,20 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
>> else
>> err = msg_len;
>>
>> + if (sinfo_flags & SCTP_EOF) {
>> + if (sctp_state(asoc, ESTABLISHED)) {
>> + SCTP_DEBUG_PRINTK("Shutting down association: %p\n",
>> + asoc);
>> + sctp_primitive_SHUTDOWN(asoc, NULL);
>> + } else {
>> + /* Delay to shutdown association until assoc enter
>> + * ESTABLISHED state
>> + */
>> + asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE] = HZ/20;
>> + asoc->autoclose = 1;
>> + }
>> + }
>> +
>>
> Interesting approach and I applaud for creativity, but it doesn't work if there is
> data loss.
>
> I see only one way out of this mess and that's to remove the SHUTDOWN_PENDING
> state and make that a modifier/flag that can be set on other states <= ESTABLISHED.
>
Do you mean we should support multi send() with EOF flag?
send(msg, SCTP_EOF);
send(msg, SCTP_EOF);
...
> In other words, if the user has queued up data to the association, even if it is
> not established, we should exhaust all retransmits before failing.
>
shutdown after all the outdata is acked?
> -vlad
>
>
>> /* If we are already past ASSOCIATE, the lower
>> * layers are responsible for association cleanup.
>> */
>>
>
>
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