kernel/linux.git/net/ipv4/tcp_cong.c, branch linux-4.16.y

tcp: Namespace-ify sysctl_tcp_default_congestion_control

2017-11-15T05:09:52+00:00

Make default TCP default congestion control to a per namespace value. This changes default congestion control to a pointer to congestion ops (rather than implicit as first element of available lsit). The congestion control setting of new namespaces is inherited from the current setting of the root namespace. Signed-off-by: Stephen Hemminger Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2017-09-02T00:42:05+00:00

Three cases of simple overlapping changes. Signed-off-by: David S. Miller

tcp: fix refcnt leak with ebpf congestion control

2017-08-26T00:16:27+00:00

There are a few bugs around refcnt handling in the new BPF congestion control setsockopt: - The new ca is assigned to icsk->icsk_ca_ops even in the case where we cannot get a reference on it. This would lead to a use after free, since that ca is going away soon. - Changing the congestion control case doesn't release the refcnt on the previous ca. - In the reinit case, we first leak a reference on the old ca, then we call tcp_reinit_congestion_control on the ca that we have just assigned, leading to deinitializing the wrong ca (->release of the new ca on the old ca's data) and releasing the refcount on the ca that we actually want to use. This is visible by building (for example) BIC as a module and setting net.ipv4.tcp_congestion_control=bic, and using tcp_cong_kern.c from samples/bpf. This patch fixes the refcount issues, and moves reinit back into tcp core to avoid passing a ca pointer back to BPF. Fixes: 91b5b21c7c16 ("bpf: Add support for changing congestion control") Signed-off-by: Sabrina Dubroca Acked-by: Lawrence Brakmo Signed-off-by: David S. Miller

tcp: fix cwnd undo in Reno and HTCP congestion controls

2017-08-07T04:25:10+00:00

Using ssthresh to revert cwnd is less reliable when ssthresh is bounded to 2 packets. This patch uses an existing variable in TCP "prior_cwnd" that snapshots the cwnd right before entering fast recovery and RTO recovery in Reno. This fixes the issue discussed in netdev thread: "A buggy behavior for Linux TCP Reno and HTCP" https://www.spinics.net/lists/netdev/msg444955.html Suggested-by: Neal Cardwell Reported-by: Wei Sun Signed-off-by: Yuchung Cheng Signed-off-by: Neal Cardwell Signed-off-by: David S. Miller

bpf: Add support for changing congestion control

2017-07-01T23:15:14+00:00

Added support for changing congestion control for SOCK_OPS bpf programs through the setsockopt bpf helper function. It also adds a new SOCK_OPS op, BPF_SOCK_OPS_NEEDS_ECN, that is needed for congestion controls, like dctcp, that need to enable ECN in the SYN packets. Signed-off-by: Lawrence Brakmo Signed-off-by: David S. Miller

tcp: disallow cwnd undo when switching congestion control

2017-06-02T18:18:13+00:00

When the sender switches its congestion control during loss recovery, if the recovery is spurious then it may incorrectly revert cwnd and ssthresh to the older values set by a previous congestion control. Consider a congestion control (like BBR) that does not use ssthresh and keeps it infinite: the connection may incorrectly revert cwnd to an infinite value when switching from BBR to another congestion control. This patch fixes it by disallowing such cwnd undo operation upon switching congestion control. Note that undo_marker is not reset s.t. the packets that were incorrectly marked lost would be corrected. We only avoid undoing the cwnd in tcp_undo_cwnd_reduction(). Signed-off-by: Yuchung Cheng Signed-off-by: Soheil Hassas Yeganeh Signed-off-by: Neal Cardwell Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

tcp: memset ca_priv data to 0 properly

2017-04-26T18:58:32+00:00

Always zero out ca_priv data in tcp_assign_congestion_control() so that ca_priv data is cleared out during socket creation. Also always zero out ca_priv data in tcp_reinit_congestion_control() so that when cc algorithm is changed, ca_priv data is cleared out as well. We should still zero out ca_priv data even in TCP_CLOSE state because user could call connect() on AF_UNSPEC to disconnect the socket and leave it in TCP_CLOSE state and later call setsockopt() to switch cc algorithm on this socket. Fixes: 2b0a8c9ee ("tcp: add CDG congestion control") Reported-by: Andrey Konovalov Signed-off-by: Wei Wang Acked-by: Eric Dumazet Acked-by: Yuchung Cheng Acked-by: Neal Cardwell Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2016-11-22T18:27:16+00:00

All conflicts were simple overlapping changes except perhaps for the Thunder driver. That driver has a change_mtu method explicitly for sending a message to the hardware. If that fails it returns an error. Normally a driver doesn't need an ndo_change_mtu method becuase those are usually just range changes, which are now handled generically. But since this extra operation is needed in the Thunder driver, it has to stay. However, if the message send fails we have to restore the original MTU before the change because the entire call chain expects that if an error is thrown by ndo_change_mtu then the MTU did not change. Therefore code is added to nicvf_change_mtu to remember the original MTU, and to restore it upon nicvf_update_hw_max_frs() failue. Signed-off-by: David S. Miller

tcp: make undo_cwnd mandatory for congestion modules

2016-11-21T18:20:17+00:00

The undo_cwnd fallback in the stack doubles cwnd based on ssthresh, which un-does reno halving behaviour. It seems more appropriate to let congctl algorithms pair .ssthresh and .undo_cwnd properly. Add a 'tcp_reno_undo_cwnd' function and wire it up for all congestion algorithms that used to rely on the fallback. Cc: Eric Dumazet Cc: Yuchung Cheng Cc: Neal Cardwell Signed-off-by: Florian Westphal Signed-off-by: David S. Miller

tcp: zero ca_priv area when switching cc algorithms

2016-11-21T18:13:56+00:00

We need to zero out the private data area when application switches connection to different algorithm (TCP_CONGESTION setsockopt). When congestion ops get assigned at connect time everything is already zeroed because sk_alloc uses GFP_ZERO flag. But in the setsockopt case this contains whatever previous cc placed there. Signed-off-by: Florian Westphal Signed-off-by: David S. Miller