I don't understand the need for MSG_SENDPAGE_NOTLAST and I'm hoping someone can
enlighten me.
According to commit 35f9c09 ('tcp: tcp_sendpages() should call tcp_push()
once'):
"We need to call tcp_flush() at the end of the last page processed in
tcp_sendpages(), or else transmits can be deferred and future sends
stall."
I don't understand why we need to differentiate between the user setting
MSG_MORE
and splice indicating that more data is going to be sent.
if the user passed MSG_MORE and didn't push any extra data, isn't it the users
fault?
Do we need it because poorly written applications were broken when
MSG_MORE was added to tcp_sendpage? Or is there a deeper reason?
The reason I'm asking is that we are working on a kernel TLS implementation
and I would like to know if we can coalesce multiple tls_sendpage calls with
MSG_MORE into a single
tls record or whether we must push out the record as soon as
MSG_SENDPAGE_NOTLAST is cleared?
Thanks,
Ilya
