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

Pull networking updates from David Miller:
 "This is a re-do of the net-next pull request for the current merge
  window.  The only difference from the one I made the other day is that
  this has Eliezer's interface renames and the timeout handling changes
  made based upon your feedback, as well as a few bug fixes that have
  trickeled in.

  Highlights:

   1) Low latency device polling, eliminating the cost of interrupt
      handling and context switches.  Allows direct polling of a network
      device from socket operations, such as recvmsg() and poll().

      Currently ixgbe, mlx4, and bnx2x support this feature.

      Full high level description, performance numbers, and design in
      commit 0a4db187a999 ("Merge branch 'll_poll'")

      From Eliezer Tamir.

   2) With the routing cache removed, ip_check_mc_rcu() gets exercised
      more than ever before in the case where we have lots of multicast
      addresses.  Use a hash table instead of a simple linked list, from
      Eric Dumazet.

   3) Add driver for Atheros CQA98xx 802.11ac wireless devices, from
      Bartosz Markowski, Janusz Dziedzic, Kalle Valo, Marek Kwaczynski,
      Marek Puzyniak, Michal Kazior, and Sujith Manoharan.

   4) Support reporting the TUN device persist flag to userspace, from
      Pavel Emelyanov.

   5) Allow controlling network device VF link state using netlink, from
      Rony Efraim.

   6) Support GRE tunneling in openvswitch, from Pravin B Shelar.

   7) Adjust SOCK_MIN_RCVBUF and SOCK_MIN_SNDBUF for modern times, from
      Daniel Borkmann and Eric Dumazet.

   8) Allow controlling of TCP quickack behavior on a per-route basis,
      from Cong Wang.

   9) Several bug fixes and improvements to vxlan from Stephen
      Hemminger, Pravin B Shelar, and Mike Rapoport.  In particular,
      support receiving on multiple UDP ports.

  10) Major cleanups, particular in the area of debugging and cookie
      lifetime handline, to the SCTP protocol code.  From Daniel
      Borkmann.

  11) Allow packets to cross network namespaces when traversing tunnel
      devices.  From Nicolas Dichtel.

  12) Allow monitoring netlink traffic via AF_PACKET sockets, in a
      manner akin to how we monitor real network traffic via ptype_all.
      From Daniel Borkmann.

  13) Several bug fixes and improvements for the new alx device driver,
      from Johannes Berg.

  14) Fix scalability issues in the netem packet scheduler's time queue,
      by using an rbtree.  From Eric Dumazet.

  15) Several bug fixes in TCP loss recovery handling, from Yuchung
      Cheng.

  16) Add support for GSO segmentation of MPLS packets, from Simon
      Horman.

  17) Make network notifiers have a real data type for the opaque
      pointer that's passed into them.  Use this to properly handle
      network device flag changes in arp_netdev_event().  From Jiri
      Pirko and Timo Teräs.

  18) Convert several drivers over to module_pci_driver(), from Peter
      Huewe.

  19) tcp_fixup_rcvbuf() can loop 500 times over loopback, just use a
      O(1) calculation instead.  From Eric Dumazet.

  20) Support setting of explicit tunnel peer addresses in ipv6, just
      like ipv4.  From Nicolas Dichtel.

  21) Protect x86 BPF JIT against spraying attacks, from Eric Dumazet.

  22) Prevent a single high rate flow from overruning an individual cpu
      during RX packet processing via selective flow shedding.  From
      Willem de Bruijn.

  23) Don't use spinlocks in TCP md5 signing fast paths, from Eric
      Dumazet.

  24) Don't just drop GSO packets which are above the TBF scheduler's
      burst limit, chop them up so they are in-bounds instead.  Also
      from Eric Dumazet.

  25) VLAN offloads are missed when configured on top of a bridge, fix
      from Vlad Yasevich.

  26) Support IPV6 in ping sockets.  From Lorenzo Colitti.

  27) Receive flow steering targets should be updated at poll() time
      too, from David Majnemer.

  28) Fix several corner case regressions in PMTU/redirect handling due
      to the routing cache removal, from Timo Teräs.

  29) We have to be mindful of ipv4 mapped ipv6 sockets in
      upd_v6_push_pending_frames().  From Hannes Frederic Sowa.

  30) Fix L2TP sequence number handling bugs, from James Chapman."

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1214 commits)
  drivers/net: caif: fix wrong rtnl_is_locked() usage
  drivers/net: enic: release rtnl_lock on error-path
  vhost-net: fix use-after-free in vhost_net_flush
  net: mv643xx_eth: do not use port number as platform device id
  net: sctp: confirm route during forward progress
  virtio_net: fix race in RX VQ processing
  virtio: support unlocked queue poll
  net/cadence/macb: fix bug/typo in extracting gem_irq_read_clear bit
  Documentation: Fix references to defunct linux-net@vger.kernel.org
  net/fs: change busy poll time accounting
  net: rename low latency sockets functions to busy poll
  bridge: fix some kernel warning in multicast timer
  sfc: Fix memory leak when discarding scattered packets
  sit: fix tunnel update via netlink
  dt:net:stmmac: Add dt specific phy reset callback support.
  dt:net:stmmac: Add support to dwmac version 3.610 and 3.710
  dt:net:stmmac: Allocate platform data only if its NULL.
  net:stmmac: fix memleak in the open method
  ipv6: rt6_check_neigh should successfully verify neigh if no NUD information are available
  net: ipv6: fix wrong ping_v6_sendmsg return value
  ...

1 files changed, 58 insertions, 0 deletions

diff --git a/Documentation/networking/scaling.txt b/Documentation/networking/scaling.txt
index 579994afbe0..ca6977f5b2e 100644
--- a/Documentation/networking/scaling.txt
+++ b/Documentation/networking/scaling.txt
@@ -163,6 +163,64 @@ and unnecessary. If there are fewer hardware queues than CPUs, then
 RPS might be beneficial if the rps_cpus for each queue are the ones that
 share the same memory domain as the interrupting CPU for that queue.
 
+==== RPS Flow Limit
+
+RPS scales kernel receive processing across CPUs without introducing
+reordering. The trade-off to sending all packets from the same flow
+to the same CPU is CPU load imbalance if flows vary in packet rate.
+In the extreme case a single flow dominates traffic. Especially on
+common server workloads with many concurrent connections, such
+behavior indicates a problem such as a misconfiguration or spoofed
+source Denial of Service attack.
+
+Flow Limit is an optional RPS feature that prioritizes small flows
+during CPU contention by dropping packets from large flows slightly
+ahead of those from small flows. It is active only when an RPS or RFS
+destination CPU approaches saturation.  Once a CPU's input packet
+queue exceeds half the maximum queue length (as set by sysctl
+net.core.netdev_max_backlog), the kernel starts a per-flow packet
+count over the last 256 packets. If a flow exceeds a set ratio (by
+default, half) of these packets when a new packet arrives, then the
+new packet is dropped. Packets from other flows are still only
+dropped once the input packet queue reaches netdev_max_backlog.
+No packets are dropped when the input packet queue length is below
+the threshold, so flow limit does not sever connections outright:
+even large flows maintain connectivity.
+
+== Interface
+
+Flow limit is compiled in by default (CONFIG_NET_FLOW_LIMIT), but not
+turned on. It is implemented for each CPU independently (to avoid lock
+and cache contention) and toggled per CPU by setting the relevant bit
+in sysctl net.core.flow_limit_cpu_bitmap. It exposes the same CPU
+bitmap interface as rps_cpus (see above) when called from procfs:
+
+ /proc/sys/net/core/flow_limit_cpu_bitmap
+
+Per-flow rate is calculated by hashing each packet into a hashtable
+bucket and incrementing a per-bucket counter. The hash function is
+the same that selects a CPU in RPS, but as the number of buckets can
+be much larger than the number of CPUs, flow limit has finer-grained
+identification of large flows and fewer false positives. The default
+table has 4096 buckets. This value can be modified through sysctl
+
+ net.core.flow_limit_table_len
+
+The value is only consulted when a new table is allocated. Modifying
+it does not update active tables.
+
+== Suggested Configuration
+
+Flow limit is useful on systems with many concurrent connections,
+where a single connection taking up 50% of a CPU indicates a problem.
+In such environments, enable the feature on all CPUs that handle
+network rx interrupts (as set in /proc/irq/N/smp_affinity).
+
+The feature depends on the input packet queue length to exceed
+the flow limit threshold (50%) + the flow history length (256).
+Setting net.core.netdev_max_backlog to either 1000 or 10000
+performed well in experiments.
+
 
 RFS: Receive Flow Steering
 ==========================