1. 02 May, 2019 14 commits
  2. 01 May, 2019 26 commits
    • David S. Miller's avatar
      Merge branch 'net-mvpp2-cls-Add-classification' · f76c4b57
      David S. Miller authored
      Maxime Chevallier says:
      
      ====================
      net: mvpp2: cls: Add classification
      
      This series is a rework of the previously standalone patch adding
      classification support for mvpp2 :
      
      https://lore.kernel.org/netdev/20190423075031.26074-1-maxime.chevallier@bootlin.com/
      
      This patch has been reworked according to Saeed's review, to make sure
      that the location of the rule is always respected and serves as a way to
      prioritize rules between each other. This the 3rd iteration of this
      submission, but since it's now a series, I reset the revision numbering.
      
      This series implements that in a limited configuration for now, since we
      limit the total number of rules per port to 4.
      
      The main factors for this limitation are that :
       - We share the classification tables between all ports (4 max, although
         one is only used for internal loopback), hence we have to perform a
         logical separation between rules, which is done today by dedicated
         ranges for each port in each table
      
       - The "Flow table", which dictates which lookups operations are
         performed for an ingress packet, in subdivided into 22 "sub flows",
         each corresponding to a traffic type based on the L3 proto, L4
         proto, the presence or not of a VLAN tag and the L3 fragmentation.
      
         This makes so that when adding a rule, it has to be added into each
         of these subflows, introducing duplications of entries and limiting
         our max number of entries.
      
      These limitations can be overcomed in several ways, but for readability
      sake, I'd rather submit basic classification offload support for now,
      and improve it gradually.
      
      This series also adds a small cosmetic cleanup patch (1), and also adds
      support for the "Drop" action compared to the first submission of this
      feature. It is simple enough to be added with this basic support.
      
      Compared to the first submissions, the NETIF_F_NTUPLE flag was also
      removed, following Saeed's comment.
      ====================
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      f76c4b57
    • Maxime Chevallier's avatar
      net: mvpp2: cls: Allow dropping packets with classification offload · bec2d46d
      Maxime Chevallier authored
      This commit introduces support for the "Drop" action in classification
      offload. This corresponds to the "-1" action with ethtool -N.
      
      This is achieved using the color marking actions available in the C2
      engine, which associate a color to a packet. These colors can be either
      Green, Yellow or Red, Red meaning that the packet should be dropped.
      
      Green and Yellow colors are interpreted by the Policer, which isn't
      supported yet.
      
      This method of dropping using the Classifier is different than the
      already existing early-drop features, such as VLAN filtering and MAC
      UC/MC filtering, which are performed during the Parsing step, and
      therefore take precedence over classification actions.
      Signed-off-by: default avatarMaxime Chevallier <maxime.chevallier@bootlin.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      bec2d46d
    • Maxime Chevallier's avatar
      net: mvpp2: cls: Add Classification offload support · 90b509b3
      Maxime Chevallier authored
      This commit introduces basic classification offloading support for the
      PPv2 controller.
      
      The PPv2 classifier has many classification engines, for now we only use
      the C2 TCAM match engine.
      
      This engine allows to perform ternary lookups on 64 bits keys (called
      Header Extracted Key), that are built by extracting fields from the packet
      header and concatenating them. At most 4 fields can be extracted for a
      single lookup.
      
      This basic implementation allows to build the HEK from the following
      fields :
       - L4 source and destination ports (for UDP and TCP)
      
      More fields are to be added in the future.
      
      Classification flows are added through the ethtool interface, using the
      newly introduced flow_rule infrastructure as an internal rule
      representation, allowing to more easily implement tc flower rules if
      need be.
      
      The internal design for now allocates one range of 4 rules per port
      due to the internal design of the flow table, which uses 22 sub-flows.
      
      When inserting a classification rule, the rule is created in every
      relevant sub-flow.
      
      This low rule-count is a very simple design which reaches quickly the
      limitations of the flow table ordering, but guarantees that the rule
      ordering will always be respected.
      
      This commit only introduces support for the "steer to rxq" action.
      Signed-off-by: default avatarMaxime Chevallier <maxime.chevallier@bootlin.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      90b509b3
    • Maxime Chevallier's avatar
      net: mvpp2: cls: Use a bitfield to represent the flow_type · 84e90b0b
      Maxime Chevallier authored
      As of today, the classification code is used only for RSS. We split the
      incoming traffic into multiple flows, that correspond to the ethtool
      flow_type parameter.
      
      We don't want to use the ethtool flow definitions such as TCP_V4_FLOW,
      for several reason :
      
       - We want to decorrelate the driver code from ethtool as much as
         possible, so that we can easily use other interfaces such as tc flower,
      
       - We want the flow_type to be a bitfield, so that we can match flows
         embedded into each other, such as TCP4 which is a subset of IP4.
      
      This commit does the conversion to the newer type.
      Signed-off-by: default avatarMaxime Chevallier <maxime.chevallier@bootlin.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      84e90b0b
    • Maxime Chevallier's avatar
      net: mvpp2: cls: Remove extra whitespace in mvpp2_cls_flow_write · 6f16a465
      Maxime Chevallier authored
      Cosmetic patch removing extra whitespaces when writing the flow_table
      entries
      Signed-off-by: default avatarMaxime Chevallier <maxime.chevallier@bootlin.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      6f16a465
    • David S. Miller's avatar
      Merge branch 'net-ll_temac-x86_64-support' · 2a369ae0
      David S. Miller authored
      Esben Haabendal says:
      
      ====================
      net: ll_temac: x86_64 support
      
      This patch series adds support for use of ll_temac driver with
      platform_data configuration and fixes endianess and 64-bit problems so
      that it can be used on x86_64 platform.
      
      A few bugfixes are also included.
      
      Changes since v2:
        - Fixed lp->indirect_mutex initialization regression for OF
          platforms introduced in v2
      
      Changes since v1:
        - Make indirect_mutex specification mandatory when using platform_data
        - Move header to include/linux/platform_data
        - Enable COMPILE_TEST for XILINX_LL_TEMAC
        - Rebased to v5.1-rc7
      ====================
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      2a369ae0
    • Esben Haabendal's avatar
      net: ll_temac: Enable DMA when ready, not before · 73f7375d
      Esben Haabendal authored
      As soon as TAILDESCR_PTR is written, DMA transfers might start.
      Let's ensure we are ready to receive DMA IRQ's before doing that.
      Signed-off-by: default avatarEsben Haabendal <esben@geanix.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      73f7375d
    • Esben Haabendal's avatar
      net: ll_temac: Allow configuration of IRQ coalescing · 7e97a194
      Esben Haabendal authored
      This allows custom setup of IRQ coalescing for platforms using legacy
      platform_device. The irq timeout and count parameters can be used for
      tuning cpu load vs. latency.
      
      I have maintained the 0x00000400 bit in TX_CHNL_CTRL.  It is specified as
      unused in the documentation I have available.  It does not make any
      difference in the hardware I have available, so it is left in to not risk
      breaking other platforms where it might be used.
      Signed-off-by: default avatarEsben Haabendal <esben@geanix.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      7e97a194
    • Esben Haabendal's avatar
      net: ll_temac: Replace bad usage of msleep() with usleep_range() · 901d14ab
      Esben Haabendal authored
      Use usleep_range() to avoid problems with msleep() actually sleeping
      much longer than expected.
      Signed-off-by: default avatarEsben Haabendal <esben@geanix.com>
      Reviewed-by: default avatarAndrew Lunn <andrew@lunn.ch>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      901d14ab
    • Esben Haabendal's avatar
      net: ll_temac: Fix bug causing buffer descriptor overrun · 2c9938e7
      Esben Haabendal authored
      As we are actually using a BD for both the skb and each frag contained in
      it, the oldest TX BD would be overwritten when there was exactly one BD
      less than needed.
      Signed-off-by: default avatarEsben Haabendal <esben@geanix.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      2c9938e7
    • Esben Haabendal's avatar
      net: ll_temac: Fix iommu/swiotlb leak · a8c9bd3b
      Esben Haabendal authored
      Unmap the actual buffer length, not the amount of data received, avoiding
      resource exhaustion of swiotlb (seen on x86_64 platform).
      Signed-off-by: default avatarEsben Haabendal <esben@geanix.com>
      Reviewed-by: default avatarAndrew Lunn <andrew@lunn.ch>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      a8c9bd3b
    • Esben Haabendal's avatar
      net: ll_temac: Support indirect_mutex share within TEMAC IP · f14f5c11
      Esben Haabendal authored
      Indirect register access goes through a DCR bus bridge, which
      allows only one outstanding transaction.  And to make matters
      worse, each TEMAC IP block contains two Ethernet interfaces, and
      although they seem to have separate registers for indirect access,
      they actually share the registers.  Or to be more specific, MSW, LSW
      and CTL registers are physically shared between Ethernet interfaces
      in same TEMAC IP, with RDY register being (almost) specificic to
      the Ethernet interface.  The 0x10000 bit in RDY reflects combined
      bus ready state though.
      
      So we need to take care to synchronize not only within a single
      device, but also between devices in same TEMAC IP.
      
      This commit allows to do that with legacy platform devices.
      
      For OF devices, the xlnx,compound parent of the temac node should be
      used to find siblings, and setup a shared indirect_mutex between them.
      I will leave this work to somebody else, as I don't have hardware to
      test that.  No regression is introduced by that, as before this commit
      using two Ethernet interfaces in same TEMAC block is simply broken.
      Signed-off-by: default avatarEsben Haabendal <esben@geanix.com>
      Reviewed-by: default avatarAndrew Lunn <andrew@lunn.ch>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      f14f5c11
    • Esben Haabendal's avatar
      net: ll_temac: Allow use on x86 platforms · 2c02c37e
      Esben Haabendal authored
      With little-endian and 64-bit support in place, the ll_temac driver can
      now be used on x86 and x86_64 platforms.
      
      And while at it, enable COMPILE_TEST also.
      Signed-off-by: default avatarEsben Haabendal <esben@geanix.com>
      Reviewed-by: default avatarAndrew Lunn <andrew@lunn.ch>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      2c02c37e
    • Esben Haabendal's avatar
      net: ll_temac: Fix support for little-endian platforms · fdd7454e
      Esben Haabendal authored
      Both TEMAC and SDMA is big-endian, so make sure that all values in SDMA
      buffer descriptors (cmdac_bd) are handled as big-endian, independent of the
      host endianness. With all currently supported platforms being big-endian,
      this change does not make a change for any of them.
      
      Note, when using app3 and app4 for piggybacking skb pointers there is no
      need to care about endianness, as neither TEMAC nor SDMA access app3 and
      app4 in TX buffer descriptors.
      Signed-off-by: default avatarEsben Haabendal <esben@geanix.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      fdd7454e
    • Esben Haabendal's avatar
      net: ll_temac: Add support for non-native register endianness · a3246dc4
      Esben Haabendal authored
      Replace the powerpc specific MMIO register access functions with the
      generic big-endian mmio access functions, and add support for
      little-endian access depending on configuration.
      
      Big-endian access is maintained as the default, but little-endian can
      be configured in device-tree binding or in platform data.
      
      The temac_ior()/temac_iow() functions are replaced with macro wrappers
      to avoid modifying existing code more than necessary.
      Signed-off-by: default avatarEsben Haabendal <esben@geanix.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      a3246dc4
    • Esben Haabendal's avatar
      net: ll_temac: Fix support for 64-bit platforms · d84aec42
      Esben Haabendal authored
      The use of buffer descriptor APP4 field (32-bit) for storing skb pointer
      obviously does not work on 64-bit platforms.
      As APP3 is also unused, we can use that to store the other half of 64-bit
      pointer values.
      
      Contrary to what is hinted at in commit message of commit 15bfe05c
      ("net: ethernet: xilinx: Mark XILINX_LL_TEMAC broken on 64-bit")
      there are no other pointers stored in cdmac_bd.
      Signed-off-by: default avatarEsben Haabendal <esben@geanix.com>
      Reviewed-by: default avatarAndrew Lunn <andrew@lunn.ch>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      d84aec42
    • Esben Haabendal's avatar
      net: ll_temac: Extend support to non-device-tree platforms · 8425c41d
      Esben Haabendal authored
      Support initialization with platdata, so the driver can be used on
      non-device-tree platforms.
      
      For currently supported device-tree platforms, the driver should behave
      as before.
      Signed-off-by: default avatarEsben Haabendal <esben@geanix.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      8425c41d
    • Esben Haabendal's avatar
      net: ll_temac: Fix and simplify error handling by using devres functions · a63625d2
      Esben Haabendal authored
      As a side effect, a few error cases are fixed.
      
      If of_iomap() of sdma_regs failed, no error code was returned.  Fixed to
      return -ENOMEM similar to of_iomap() fail of regs.
      
      If sysfs_create_group() or register_netdev() failed, lp->phy_node was not
      released.
      
      Finally, the order in remove function is corrected to be reverse order
      of what is done in probe, i.e. calling temac_mdio_teardown() last, so we
      unregister the netdev that most likely is using the mdio_bus first.
      Signed-off-by: default avatarEsben Haabendal <esben@geanix.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      a63625d2
    • YueHaibing's avatar
      net: ethernet: ti: cpsw: Fix inconsistent IS_ERR and PTR_ERR in cpsw_probe() · ac97a359
      YueHaibing authored
      Fix inconsistent IS_ERR and PTR_ERR in cpsw_probe,
      The proper pointer to use is clk instead of mode.
      
      This issue was detected with the help of Coccinelle.
      
      Fixes: 83a8471b ("net: ethernet: ti: cpsw: refactor probe to group common hw initialization")
      Signed-off-by: default avatarYueHaibing <yuehaibing@huawei.com>
      Reviewed-by: default avatarAndrew Lunn <andrew@lunn.ch>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      ac97a359
    • David S. Miller's avatar
      Merge branch 'net-sched-taprio-change-schedules' · 5b27aafa
      David S. Miller authored
      Vinicius Costa Gomes says:
      
      ====================
      net/sched: taprio change schedules
      
      Changes from RFC:
       - Removed the patches for taprio offloading, because of the lack of
         in-tree users;
       - Updated the links to point to the PATCH version of this series;
      
      Original cover letter:
      
      Overview
      --------
      
      This RFC has two objectives, it adds support for changing the running
      schedules during "runtime", explained in more detail later, and
      proposes an interface between taprio and the drivers for hardware
      offloading.
      
      These two different features are presented together so it's clear what
      the "final state" would look like. But after the RFC stage, they can
      be proposed (and reviewed) separately.
      
      Changing the schedules without disrupting traffic is important for
      handling dynamic use cases, for example, when streams are
      added/removed and when the network configuration changes.
      
      Hardware offloading support allows schedules to be more precise and
      have lower resource usage.
      
      Changing schedules
      ------------------
      
      The same as the other interfaces we proposed, we try to use the same
      concepts as the IEEE 802.1Q-2018 specification. So, for changing
      schedules, there are an "oper" (operational) and an "admin" schedule.
      The "admin" schedule is mutable and not in use, the "oper" schedule is
      immutable and is in use.
      
      That is, when the user first adds an schedule it is in the "admin"
      state, and it becomes "oper" when its base-time (basically when it
      starts) is reached.
      
      What this means is that now it's possible to create taprio with a schedule:
      
      $ tc qdisc add dev IFACE parent root handle 100 taprio \
            num_tc 3 \
            map 2 2 1 0 2 2 2 2 2 2 2 2 2 2 2 2 \
            queues 1@0 1@1 2@2 \
            base-time 10000000 \
            sched-entry S 03 300000 \
            sched-entry S 02 300000 \
            sched-entry S 06 400000 \
            clockid CLOCK_TAI
      
      And then, later, after the previous schedule is "promoted" to "oper",
      add a new ("admin") schedule to be used some time later:
      
      $ tc qdisc change dev IFACE parent root handle 100 taprio \
            base-time 1553121866000000000 \
            sched-entry S 02 500000 \
            sched-entry S 0f 400000 \
            clockid CLOCK_TAI
      
      When enabling the ability to change schedules, it makes sense to add
      two more defined knobs to schedules: "cycle-time" allows to truncate a
      cycle to some value, so it repeats after a well-defined value;
      "cycle-time-extension" controls how much an entry can be extended if
      it's the last one before the change of schedules, the reason is to
      avoid a very small cycle when transitioning from a schedule to
      another.
      
      With these, taprio in the software mode should provide a fairly
      complete implementation of what's defined in the Enhancements for
      Scheduled Traffic parts of the specification.
      
      Hardware offload
      ----------------
      
      Some workloads require better guarantees from their schedules than
      what's provided by the software implementation. This series proposes
      an interface for configuring schedules into compatible network
      controllers.
      
      This part is proposed together with the support for changing
      schedules, because it raises questions like, should the "qdisc" side
      be responsible of providing visibility into the schedules or should it
      be the driver?
      
      In this proposal, the driver is called passing the new schedule as
      soon as it is validated, and the "core" qdisc takes care of displaying
      (".dump()") the correct schedules at all times. It means that some
      logic would need to be duplicated in the driver, if the hardware
      doesn't have support for multiple schedules. But as taprio doesn't
      have enough information about the underlying controller to know how
      much in advance a schedule needs to be informed to the hardware, it
      feels like a fair compromise.
      
      The hardware offloading part of this proposal also tries to define an
      interface for frame-preemption and how it interacts with the
      scheduling of traffic, see Section 8.6.8.4 of IEEE 802.1Q-2018 for
      more information.
      
      One important difference between the qdisc interface and the
      qdisc-driver interface, is that the "gate mask" on the qdisc side
      references traffic classes, that is bit 0 of the gate mask means
      Traffic Class 0, and in the driver interface, it specifies the queues,
      that is bit 0 means queue 0. That is to say that taprio converts the
      references to traffic classes to references to queues before sending
      the offloading request to the driver.
      
      Request for help
      ----------------
      
      I would like that interested driver maintainers could take a look at
      the proposed interface and see if it's going to be too awkward for any
      particular device. Also, pointers to available documentation would be
      appreciated. The idea here is to start a discussion so we can have an
      interface that would work for multiple vendors.
      
      Links
      -----
      
      kernel patches:
      https://github.com/vcgomes/net-next/tree/taprio-add-support-for-change-v3
      
      iproute2 patches:
      https://github.com/vcgomes/iproute2/tree/taprio-add-support-for-change-v3
      ====================
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      5b27aafa
    • Vinicius Costa Gomes's avatar
      taprio: Add support for cycle-time-extension · c25031e9
      Vinicius Costa Gomes authored
      IEEE 802.1Q-2018 defines the concept of a cycle-time-extension, so the
      last entry of a schedule before the start of a new schedule can be
      extended, so "too-short" entries can be avoided.
      Signed-off-by: default avatarVinicius Costa Gomes <vinicius.gomes@intel.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      c25031e9
    • Vinicius Costa Gomes's avatar
      taprio: Add support for setting the cycle-time manually · 6ca6a665
      Vinicius Costa Gomes authored
      IEEE 802.1Q-2018 defines that a the cycle-time of a schedule may be
      overridden, so the schedule is truncated to a determined "width".
      Signed-off-by: default avatarVinicius Costa Gomes <vinicius.gomes@intel.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      6ca6a665
    • Vinicius Costa Gomes's avatar
      taprio: Add support adding an admin schedule · a3d43c0d
      Vinicius Costa Gomes authored
      The IEEE 802.1Q-2018 defines two "types" of schedules, the "Oper" (from
      operational?) and "Admin" ones. Up until now, 'taprio' only had
      support for the "Oper" one, added when the qdisc is created. This adds
      support for the "Admin" one, which allows the .change() operation to
      be supported.
      
      Just for clarification, some quick (and dirty) definitions, the "Oper"
      schedule is the currently (as in this instant) running one, and it's
      read-only. The "Admin" one is the one that the system configurator has
      installed, it can be changed, and it will be "promoted" to "Oper" when
      it's 'base-time' is reached.
      
      The idea behing this patch is that calling something like the below,
      (after taprio is already configured with an initial schedule):
      
      $ tc qdisc change taprio dev IFACE parent root 	     \
           	   base-time X 	     	   	       	     \
           	   sched-entry <CMD> <GATES> <INTERVAL>	     \
      	   ...
      
      Will cause a new admin schedule to be created and programmed to be
      "promoted" to "Oper" at instant X. If an "Admin" schedule already
      exists, it will be overwritten with the new parameters.
      
      Up until now, there was some code that was added to ease the support
      of changing a single entry of a schedule, but was ultimately unused.
      Now, that we have support for "change" with more well thought
      semantics, updating a single entry seems to be less useful.
      
      So we remove what is in practice dead code, and return a "not
      supported" error if the user tries to use it. If changing a single
      entry would make the user's life easier we may ressurrect this idea,
      but at this point, removing it simplifies the code.
      
      For now, only the schedule specific bits are allowed to be added for a
      new schedule, that means that 'clockid', 'num_tc', 'map' and 'queues'
      cannot be modified.
      
      Example:
      
      $ tc qdisc change dev IFACE parent root handle 100 taprio \
            base-time $BASE_TIME \
            sched-entry S 00 500000 \
            sched-entry S 0f 500000 \
            clockid CLOCK_TAI
      
      The only change in the netlink API introduced by this change is the
      introduction of an "admin" type in the response to a dump request,
      that type allows userspace to separate the "oper" schedule from the
      "admin" schedule. If userspace doesn't support the "admin" type, it
      will only display the "oper" schedule.
      Signed-off-by: default avatarVinicius Costa Gomes <vinicius.gomes@intel.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      a3d43c0d
    • Vinicius Costa Gomes's avatar
      taprio: Fix potencial use of invalid memory during dequeue() · 8c79f0ea
      Vinicius Costa Gomes authored
      Right now, this isn't a problem, but the next commit allows schedules
      to be added during runtime. When a new schedule transitions from the
      inactive to the active state ("admin" -> "oper") the previous one can
      be freed, if it's freed just after the RCU read lock is released, we
      may access an invalid entry.
      
      So, we should take care to protect the dequeue() flow, so all the
      places that access the entries are protected by the RCU read lock.
      Signed-off-by: default avatarVinicius Costa Gomes <vinicius.gomes@intel.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      8c79f0ea
    • David S. Miller's avatar
      Merge branch 'tcp-undo-congestion' · cd86972a
      David S. Miller authored
      Yuchung Cheng says:
      
      ====================
      undo congestion window on spurious SYN or SYNACK timeout
      
      Linux TCP currently uses the initial congestion window of 1 packet
      if multiple SYN or SYNACK timeouts per RFC6298. However such
      timeouts are often spurious on wireless or cellular networks that
      experience high delay variances (e.g. ramping up dormant radios or
      local link retransmission). Another case is when the underlying
      path is longer than the default SYN timeout (e.g. 1 second). In
      these cases starting the transfer with a minimal congestion window
      is detrimental to the performance for short flows.
      
      One naive approach is to simply ignore SYN or SYNACK timeouts and
      always use a larger or default initial window. This approach however
      risks pouring gas to the fire when the network is already highly
      congested. This is particularly true in data center where application
      could start thousands to millions of connections over a single or
      multiple hosts resulting in high SYN drops (e.g. incast).
      
      This patch-set detects spurious SYN and SYNACK timeouts upon
      completing the handshake via the widely-supported TCP timestamp
      options. Upon such events the sender reverts to the default
      initial window to start the data transfer so it gets best of both
      worlds. This patch-set supports this feature for both active and
      passive as well as Fast Open or regular connections.
      ====================
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      cd86972a
    • Yuchung Cheng's avatar
      tcp: refactor setting the initial congestion window · 98fa6271
      Yuchung Cheng authored
      Relocate the congestion window initialization from tcp_init_metrics()
      to tcp_init_transfer() to improve code readability.
      Signed-off-by: default avatarYuchung Cheng <ycheng@google.com>
      Signed-off-by: default avatarNeal Cardwell <ncardwell@google.com>
      Signed-off-by: default avatarSoheil Hassas Yeganeh <soheil@google.com>
      Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      98fa6271