there are situations where MPTCP sockets should fall-back to regular TCP: this series reworks the fallback code to pursue the following goals:
1) cleanup the non fallback code, removing most of 'if (<fallback>)' in the data path 2) improve performance for non-fallback sockets, avoiding locks in poll() further work will also leverage on this changes to achieve: a) more consistent behavior of gestockopt()/setsockopt() on passive sockets after fallback b) support for "infinite maps" as per RFC8684, section 3.7 the series is made of the following items: - patch 1 lets sendmsg() / recvmsg() / poll() use the main socket also after fallback - patch 2 fixes 'simultaneous connect' scenario after fallback. The problem was present also before the rework, but the fix is much easier to implement after patch 1 - patch 3, 4, 5 are clean-ups for code that is no more needed after the fallback rework - patch 6 fixes a race condition between close() and poll(). The problem was theoretically present before the rework, but it became almost systematic after patch 1 Davide Caratti (2): net: mptcp: improve fallback to TCP mptcp: fallback in case of simultaneous connect Paolo Abeni (4): mptcp: check for plain TCP sock at accept time mptcp: create first subflow at msk creation time mptcp: __mptcp_tcp_fallback() returns a struct sock mptcp: close poll() races net/mptcp/options.c | 9 +- net/mptcp/protocol.c | 267 ++++++++++++++----------------------------- net/mptcp/protocol.h | 43 +++++++ net/mptcp/subflow.c | 57 ++++++--- 4 files changed, 175 insertions(+), 201 deletions(-) -- 2.26.2
