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Willem de Bruijn 497dbb2b97 gve: Add optional metadata descriptor type GVE_TXD_MTD
Allow drivers to pass metadata along with packet data to the device.
Introduce a new metadata descriptor type

* GVE_TXD_MTD

This descriptor is optional. If present it immediate follows the
packet descriptor and precedes the segment descriptor.

This descriptor may be repeated. Multiple metadata descriptors may
follow. There are no immediate uses for this, this is for future
proofing. At present devices allow only 1 MTD descriptor.

The lower four bits of the type_flags field encode GVE_TXD_MTD.
The upper four bits of the type_flags field encodes a *sub*type.

Introduce one such metadata descriptor subtype

* GVE_MTD_SUBTYPE_PATH

This shares path information with the device for network failure
discovery and robust response:

Linux derives ipv6 flowlabel and ECMP multipath from sk->sk_txhash,
and updates this field on error with sk_rethink_txhash. Allow the host
stack to do the same. Pass the tx_hash value if set. Also communicate
whether the path hash is set, or more exactly, what its type is. Define
two common types

  GVE_MTD_PATH_HASH_NONE
  GVE_MTD_PATH_HASH_L4

Concrete examples of error conditions that are resolved are
mentioned in the commits that add sk_rethink_txhash calls. Such as
commit 7788174e87 ("tcp: change IPv6 flow-label upon receiving
spurious retransmission").

Experimental results mirror what the theory suggests: where IPv6
FlowLabel is included in path selection (e.g., LAG/ECMP), flowlabel
rotation on TCP timeout avoids the vast majority of TCP disconnects
that would otherwise have occurred during link failures in long-haul
backbones, when an alternative path is available.

Rotation can be applied to various bad connection signals, such as
timeouts and spurious retransmissions. In aggregate, such flow level
signals can help locate network issues. Define initial common states:

  GVE_MTD_PATH_STATE_DEFAULT
  GVE_MTD_PATH_STATE_TIMEOUT
  GVE_MTD_PATH_STATE_CONGESTION
  GVE_MTD_PATH_STATE_RETRANSMIT

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David Awogbemila <awogbemila@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-12-16 10:41:54 +00:00
arch ARM: dts: qcom: sdx55: fix IPA interconnect definitions 2021-12-13 12:49:26 +00:00
block Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2021-12-08 16:06:44 -08:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Update to zstd-1.4.10 2021-11-13 15:32:30 -08:00
Documentation ice: support immediate firmware activation via devlink reload 2021-12-15 08:40:38 -08:00
drivers gve: Add optional metadata descriptor type GVE_TXD_MTD 2021-12-16 10:41:54 +00:00
fs net: add netns refcount tracker to struct seq_net_private 2021-12-10 06:38:26 -08:00
include net: phylink: add pcs_validate() method 2021-12-16 10:37:13 +00:00
init kbuild: Fix -Wimplicit-fallthrough=5 error for GCC 5.x and 6.x 2021-11-14 18:59:49 -08:00
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-11-20 10:35:54 -08:00
kernel Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-12-10 15:56:13 -08:00
lib Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-12-10 15:56:13 -08:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2021-12-08 16:06:44 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next 2021-12-15 17:29:28 -08:00
samples Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-12-10 15:56:13 -08:00
scripts Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid 2021-11-24 09:44:13 -08:00
security selinux: fix NULL-pointer dereference when hashtab allocation fails 2021-11-19 16:11:39 -05:00
sound sound fixes for 5.16-rc4 2021-12-01 10:07:39 -08:00
tools selftests: mlxsw: vxlan: Remove IPv6 test case 2021-12-15 15:05:44 +00:00
usr initramfs: Check timestamp to prevent broken cpio archive 2021-10-24 13:48:40 +09:00
virt KVM: downgrade two BUG_ONs to WARN_ON_ONCE 2021-11-26 06:43:28 -05:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap MAINTAINERS: update email address of Christian Borntraeger 2021-11-18 17:50:54 +01:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-12-10 15:56:13 -08:00
Makefile Makefile: Do not quote value for CONFIG_CC_IMPLICIT_FALLTHROUGH 2021-12-06 16:42:47 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.