Re: [PATCH mptcp-next v6 06/13] mptcp: multi subflows push_pending

[Geliang Tang <geliang.tang@suse.com>]

On Tue, Oct 11, 2022 at 03:30:43PM -0700, Mat Martineau wrote:
> On Tue, 11 Oct 2022, Geliang Tang wrote:
> 
> > This patch adds the multiple subflows support for __mptcp_push_pending().
> > Use mptcp_sched_get_send() wrapper instead of mptcp_subflow_get_send() in
> > it.
> > 
> > Check the subflow scheduled flags to test which subflow or subflows are
> > picked by the scheduler, use them to send data.
> > 
> > Signed-off-by: Geliang Tang <geliang.tang@suse.com>
> > ---
> > net/mptcp/protocol.c | 32 ++++++++++++++++++++------------
> > 1 file changed, 20 insertions(+), 12 deletions(-)
> > 
> > diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
> > index 817e539d1d12..86ac38d10bc4 100644
> > --- a/net/mptcp/protocol.c
> > +++ b/net/mptcp/protocol.c
> > @@ -1561,22 +1561,30 @@ static int __subflow_push_pending(struct sock *sk, struct sock *ssk,
> > void __mptcp_push_pending(struct sock *sk, unsigned int flags)
> > {
> > 	struct mptcp_sock *msk = mptcp_sk(sk);
> > -	struct mptcp_sendmsg_info info = {
> > -				.flags = flags,
> > -	};
> > -	struct sock *ssk;
> > 	int ret = 0;
> > 
> > again:
> > -	while (mptcp_send_head(sk) && (ssk = mptcp_subflow_get_send(msk))) {
> > -		lock_sock(ssk);
> > -		ret = __subflow_push_pending(sk, ssk, &info);
> > -		release_sock(ssk);
> > +	while (mptcp_send_head(sk) && !mptcp_sched_get_send(msk)) {
> > +		struct mptcp_subflow_context *subflow;
> > +		struct mptcp_sendmsg_info info = {
> > +			.flags = flags,
> > +		};
> > 
> > -		if (ret <= 0) {
> > -			if (ret == -EAGAIN)
> > -				goto again;
> > -			goto out;
> > +		mptcp_for_each_subflow(msk, subflow) {
> > +			if (READ_ONCE(subflow->scheduled)) {
> > +				struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
> > +
> > +				lock_sock(ssk);
> > +				ret = __subflow_push_pending(sk, ssk, &info);
> > +				release_sock(ssk);
> 
> Geliang -
> 
> It seems like this doesn't allow for redundant transmits, since
> __subflow_push_pending() updates msk->first_pending. Did you find that
> redundant sends were working correctly (maybe I've misunderstood)?

Hi Mat,

Redundant sends are not support in this series yet. It will be added in
this __subflow_push_pending() function in the next series with the
selftests patches.

There are still some issues that haven't been solved in the redundant
support patches. I'm still working on them.

Thanks,
-Geliang

> 
> - Mat
> 
> > +
> > +				if (ret <= 0) {
> > +					if (ret == -EAGAIN)
> > +						goto again;
> > +					goto out;
> > +				}
> > +				mptcp_subflow_set_scheduled(subflow, false);
> > +			}
> > 		}
> > 	}
> > 
> > -- 
> > 2.35.3
> > 
> > 
> > 
> 
> --
> Mat Martineau
> Intel