[MPTCP] Re: [PATCH mptcp] mptcp: re-check dsn before reading from subflow

On Thu, 27 Feb 2020, Florian Westphal wrote: > mptcp_subflow_data_available() is commonly called via > ssk->sk_data_ready(), in this case the mptcp socket lock > cannot be acquired. > > Therefore, while we can safely discard subflow data that > was already received up to msk->ack_seq, we cannot be sure > that 'subflow->data_avail' will still be valid at the time > userspace wants to read the data -- a previous read on a > different subflow might have carried this data already. > > In that (unlikely) event, msk->ack_seq will have been updated > and will be ahead of the subflow dsn. > > We can check for this condition and skip/resync to the expected > sequence number. > > Signed-off-by: Florian Westphal <fw(a)strlen.de&gt; > --- > I could also submit this directly for net-next, but this > patch is only needed w. MP_JOIN support. I think this is ok to integrate in the topgit tree.

It didn't apply directly due to upstream changes (sorry about the review delay) but the only conflict was straightforward to fix.