3118 Commits
Author SHA1 Message Date
Maciej W. Rozycki 75756cb4b2 ethernet: 3c509: Update documentation to match MAINTAINERS
There has been apparently a single message only ever publicly posted by
David Ruggiero, back in 2002, which added this documentation piece among
others, and MAINTAINERS was never updated accordingly.  It is therefore
doubtful that his maintainer status has actually come into effect.  Just
replace the reference then so as not to confuse people.

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Link: https://patch.msgid.link/alpine.DEB.2.21.2605201207380.1450@angie.orcam.me.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-05-21 08:28:56 -07:00
Maciej W. Rozycki 28db0338db Revert "drivers: net: 3com: 3c509: Remove this driver"
This reverts commit 91f3a27ae9.

Contrary to the assumption stated with the original commit description
this driver is in use and I'm going to maintain it for the foreseeable
future.

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Link: https://patch.msgid.link/alpine.DEB.2.21.2605201204260.1450@angie.orcam.me.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-05-21 08:28:56 -07:00
Linus Torvalds 64edfa6506 Merge tag 'net-deletions' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking deletions from Jakub Kicinski:
 "Delete some obsolete networking code

  Old code like amateur radio and NFC have long been a burden to core
  networking developers. syzbot loves to find bugs in BKL-era code, and
  noobs try to fix them.

  If we want to have a fighting chance of surviving the LLM-pocalypse
  this code needs to find a dedicated owner or get deleted. We've talked
  about these deletions multiple times in the past and every time
  someone wanted the code to stay. It is never very clear to me how many
  of those people actually use the code vs are just nostalgic to see it
  go. Amateur radio did have occasional users (or so I think) but most
  users switched to user space implementations since its all super slow
  stuff. Nobody stepped up to maintain the kernel code.

  We were lucky enough to find someone who wants to help with NFC so
  we're giving that a chance. Let's try to put the rest of this code
  behind us"

* tag 'net-deletions' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next:
  drivers: net: 8390: wd80x3: Remove this driver
  drivers: net: 8390: ultra: Remove this driver
  drivers: net: 8390: AX88190: Remove this driver
  drivers: net: fujitsu: fmvj18x: Remove this driver
  drivers: net: smsc: smc91c92: Remove this driver
  drivers: net: smsc: smc9194: Remove this driver
  drivers: net: amd: nmclan: Remove this driver
  drivers: net: amd: lance: Remove this driver
  drivers: net: 3com: 3c589: Remove this driver
  drivers: net: 3com: 3c574: Remove this driver
  drivers: net: 3com: 3c515: Remove this driver
  drivers: net: 3com: 3c509: Remove this driver
  net: packetengines: remove obsolete yellowfin driver and vendor dir
  net: packetengines: remove obsolete hamachi driver
  net: remove unused ATM protocols and legacy ATM device drivers
  net: remove ax25 and amateur radio (hamradio) subsystem
  net: remove ISDN subsystem and Bluetooth CMTP
  caif: remove CAIF NETWORK LAYER
2026-04-24 09:41:58 -07:00
Andrew Lunn a3fb9a5bf6 drivers: net: smsc: smc91c92: Remove this driver
The smc91c92 was written by David A Hinds in 1999. It is an PCMCIA
device, so unlikely to be used with modern kernels.

Remove the Documentation as well, since it refers to kernel versions
1.2.13 until 1.3.71 and FTP sites which no longer exist.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20260422-v7-0-0-net-next-driver-removal-v1-v2-8-08a5b59784d5@lunn.ch
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-23 15:57:06 -07:00
Andrew Lunn 91f3a27ae9 drivers: net: 3com: 3c509: Remove this driver
The 3c509 was written by Donald Becker between 1993-2000. It is an ISA
device, so unlikely to be used with modern kernels.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20260422-v7-0-0-net-next-driver-removal-v1-v2-1-08a5b59784d5@lunn.ch
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-23 15:56:43 -07:00
Jakub Kicinski 6deb535950 net: remove unused ATM protocols and legacy ATM device drivers
Remove the ATM protocol modules and PCI/SBUS ATM device drivers
that are no longer in active use.

The ATM core protocol stack, PPPoATM, BR2684, and USB DSL modem
drivers (drivers/usb/atm/) are retained in-tree to maintain PPP
over ATM (PPPoA) and PPPoE-over-BR2684 support for DSL connections.
The Solos ADSL2+ PCI driver is also retained.

Removed ATM protocol modules:
 - net/atm/clip.c - Classical IP over ATM (RFC 2225)
 - net/atm/lec.c - LAN Emulation Client (LANE)
 - net/atm/mpc.c, mpoa_caches.c, mpoa_proc.c - Multi-Protocol Over ATM

Removed PCI/SBUS ATM device drivers (drivers/atm/):
 - adummy, atmtcp - software/testing ATM devices
 - eni - Efficient Networks ENI155P (OC-3, ~1995)
 - fore200e - FORE Systems 200E PCI/SBUS (OC-3, ~1999)
 - he - ForeRunner HE (OC-3/OC-12, ~2000)
 - idt77105 - IDT 77105 25 Mbps ATM PHY
 - idt77252 - IDT 77252 NICStAR II (OC-3, ~2000)
 - iphase - Interphase ATM PCI (OC-3/DS3/E3)
 - lanai - Efficient Networks Speedstream 3010
 - nicstar - IDT 77201 NICStAR (155/25 Mbps, ~1999)
 - suni - PMC S/UNI SONET PHY library

Also clean up references in:
 - net/bridge/ - remove ATM LANE hook (br_fdb_test_addr_hook,
   br_fdb_test_addr)
 - net/core/dev.c - remove br_fdb_test_addr_hook export
 - defconfig files - remove ATM driver config options

The removed code is moved to an out-of-tree module package (mod-orphan).

Acked-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/20260422041846.2035118-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-23 12:21:14 -07:00
Jakub Kicinski dd8d4bc28a net: remove ax25 and amateur radio (hamradio) subsystem
Remove the amateur radio (AX.25, NET/ROM, ROSE) protocol implementation
and all associated hamradio device drivers from the kernel tree.
This set of protocols has long been a huge bug/syzbot magnet,
and since nobody stepped up to help us deal with the influx
of the AI-generated bug reports we need to move it out of tree
to protect our sanity.

The code is moved to an out-of-tree repo:
https://github.com/linux-netdev/mod-orphan
if it's cleaned up and reworked there we can accept it back.

Minimal stub headers are kept for include/net/ax25.h (AX25_P_IP,
AX25_ADDR_LEN, ax25_address) and include/net/rose.h (ROSE_ADDR_LEN)
so that the conditional integration code in arp.c and tun.c continues
to compile and work when the out-of-tree modules are loaded.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: Carlos Bilbao <carlos.bilbao@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://patch.msgid.link/20260421021824.1293976-1-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-04-23 10:24:02 -07:00
Jakub Kicinski 6d5431555d caif: remove CAIF NETWORK LAYER
Remove CAIF (Communication CPU to Application CPU Interface), the
ST-Ericsson modem protocol. The subsystem has been orphaned since 2013.
The last meaningful changes from the maintainers were in March 2013:
  a8c7687bf2 ("caif_virtio: Check that vringh_config is not null")
  b2273be8d2 ("caif_virtio: Use vringh_notify_enable correctly")
  0d2e1a2926 ("caif_virtio: Introduce caif over virtio")

Not-so-coincidentally, according to "the Internet" ST-Ericsson officially
shut down its modem joint venture in Aug 2013.

If anyone is using this code please yell!

In the 13 years since, the code has accumulated 200 non-merge commits,
of which 71 were cross-tree API changes, 21 carried Fixes: tags, and
the remaining ~110 were cleanups, doc conversions, treewide refactors,
and one partial removal (caif_hsi, ca75bcf0a8).

We are still getting fixes to this code, in the last 10 days there were
3 reports on security@ about CAIF that I have been CCed on.

UAPI constants (AF_CAIF, ARPHRD_CAIF, N_CAIF, VIRTIO_ID_CAIF) and the
SELinux classmap entry are intentionally kept for ABI stability.

Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260416182829.1440262-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-23 10:23:44 -07:00
Stanislav Fomichev 7ef83bf171 net: move promiscuity handling into netdev_rx_mode_work
Move unicast promiscuity tracking into netdev_rx_mode_work so it runs
under netdev_ops_lock instead of under the addr_lock spinlock. This
is required because __dev_set_promiscuity calls dev_change_rx_flags
and __dev_notify_flags, both of which may need to sleep.

Change ASSERT_RTNL() to netdev_ops_assert_locked() in
__dev_set_promiscuity, netif_set_allmulti and __dev_change_flags
since these are now called from the work queue under the ops lock.

Link: https://lore.kernel.org/netdev/20260214033859.43857-1-jiayuan.chen@linux.dev/
Fixes: 78cd408356 ("net: add missing instance lock to dev_set_promiscuity")
Reported-by: syzbot+2b3391f44313b3983e91@syzkaller.appspotmail.com
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20260416185712.2155425-5-sdf@fomichev.me
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-04-21 12:50:24 +02:00
Stanislav Fomichev 3554b4345d net: introduce ndo_set_rx_mode_async and netdev_rx_mode_work
Add ndo_set_rx_mode_async callback that drivers can implement instead
of the legacy ndo_set_rx_mode. The legacy callback runs under the
netif_addr_lock spinlock with BHs disabled, preventing drivers from
sleeping. The async variant runs from a work queue with rtnl_lock and
netdev_lock_ops held, in fully sleepable context.

When __dev_set_rx_mode() sees ndo_set_rx_mode_async, it schedules
netdev_rx_mode_work instead of calling the driver inline. The work
function takes two snapshots of each address list (uc/mc) under
the addr_lock, then drops the lock and calls the driver with the
work copies. After the driver returns, it reconciles the snapshots
back to the real lists under the lock.

Add netif_rx_mode_sync() to opportunistically execute the pending
workqueue update inline, so that rx mode changes are committed
before returning to userspace:
  - dev_change_flags (SIOCSIFFLAGS / RTM_NEWLINK)
  - dev_set_promiscuity
  - dev_set_allmulti
  - dev_ifsioc SIOCADDMULTI / SIOCDELMULTI
  - do_setlink (RTM_SETLINK)

Note that some deep hierarchies still do skip the lower updates via:
  - dev_uc_sync
  - dev_mc_sync

If we do end up hitting user-visible issues, we can add more calls to
netif_rx_mode_sync in specific places. But hopefully we should not,
the actual user-visible lists are still synced, it's that just HW state
that might be lagging.

Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20260416185712.2155425-3-sdf@fomichev.me
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-04-21 12:50:03 +02:00
Jakub Kicinski 03a1569c2b Merge tag 'nf-next-26-04-10' of https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next
Florian Westphal says:

====================
netfilter: updates for net-next

1-3) IPVS updates from Julian Anastasov to enhance visibility into
     IPVS internal state by exposing hash size, load factor etc and
     allows userspace to tune the load factor used for resizing hash
     tables.

4) reject empty/not nul terminated device names from xt_physdev.
   This isn't a bug fix; existing code doesn't require a c-string.
   But clean this up anyway because conceptually the interface name
   definitely should be a c-string.

5) Switch nfnetlink to skb_mac_header helpers that didn't exist back
   when this code was written.  This gives us additional debug checks
   but is not intended to change functionality.

6) Let the xt ttl/hoplimit match reject unknown operator modes.
   This is a cleanup, the evaluation function simply returns false when
   the mode is out of range.  From Marino Dzalto.

7) xt_socket match should enable defrag after all other checks. This
   bug is harmless, historically defrag could not be disabled either
   except by rmmod.

8) remove UDP-Lite conntrack support, from Fernando Fernandez Mancera.

9) Avoid a couple -Wflex-array-member-not-at-end warnings in the old
   xtables 32bit compat code, from Gustavo A. R. Silva.

10) nftables fwd expression should drop packets when their ttl/hl has
    expired.  This is a bug fix deferred, its not deemed important
    enough for -rc8.
11) Add additional checks before assuming the mac header is an ethernet
    header, from Zhengchuan Liang.

* tag 'nf-next-26-04-10' of https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next:
  netfilter: require Ethernet MAC header before using eth_hdr()
  netfilter: nft_fwd_netdev: check ttl/hl before forwarding
  netfilter: x_tables: Avoid a couple -Wflex-array-member-not-at-end warnings
  netfilter: conntrack: remove UDP-Lite conntrack support
  netfilter: xt_socket: enable defrag after all other checks
  netfilter: xt_HL: add pr_fmt and checkentry validation
  netfilter: nfnetlink: prefer skb_mac_header helpers
  netfilter: x_physdev: reject empty or not-nul terminated device names
  ipvs: add conn_lfactor and svc_lfactor sysctl vars
  ipvs: add ip_vs_status info
  ipvs: show the current conn_tab size to users
====================

Link: https://patch.msgid.link/20260410112352.23599-1-fw@strlen.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-12 09:39:21 -07:00
Andy Roulin c4f2aab121 docs: net: bridge: document stp_mode attribute
Add documentation for the IFLA_BR_STP_MODE bridge attribute in the
"User space STP helper" section of the bridge documentation. Reference
the BR_STP_MODE_* values via kernel-doc and describe the use case for
network namespace environments.

Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: Andy Roulin <aroulin@nvidia.com>
Link: https://patch.msgid.link/20260405205224.3163000-3-aroulin@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-10 15:52:25 -07:00
Julian Anastasov 8d7de5477e ipvs: add conn_lfactor and svc_lfactor sysctl vars
Allow the default load factor for the connection and service tables
to be configured.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Florian Westphal <fw@strlen.de>
2026-04-10 12:16:26 +02:00
Daniel Borkmann d04686d9bc net: Implement netdev_nl_queue_create_doit
Implement netdev_nl_queue_create_doit which creates a new rx queue in a
virtual netdev and then leases it to a rx queue in a physical netdev.

Example with ynl client:

  # ynl --family netdev --output-json --do queue-create \
        --json '{"ifindex": 8, "type": "rx", "lease": {"ifindex": 4, "queue": {"type": "rx", "id": 15}}}'
  {'id': 1}

Note that the netdevice locking order is always from the virtual to
the physical device.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Co-developed-by: David Wei <dw@davidwei.uk>
Signed-off-by: David Wei <dw@davidwei.uk>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/20260402231031.447597-3-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-09 18:21:45 -07:00
Or Har-Toov 78c327c172 devlink: Document resource scope filtering
Document the scope parameter for devlink resource show, which allows
filtering the dump to device-level or port-level resources only.

Signed-off-by: Or Har-Toov <ohartoov@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/20260407194107.148063-13-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-08 19:55:39 -07:00
Or Har-Toov 170e160a0e devlink: Document port-level resources and full dump
Document the port-level resource support and the option to dump all
resources, including both device-level and port-level entries.

Signed-off-by: Or Har-Toov <ohartoov@nvidia.com>
Reviewed-by: Shay Drori <shayd@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/20260407194107.148063-10-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-08 19:55:39 -07:00
Vladimir Oltean b773b99352 net: dsa: remove struct platform_data
This is not used anywhere in the kernel.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20260406212158.721806-2-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-08 19:38:52 -07:00
Ryohei Kinugawa ed8edcd475 docs/mlx5: Fix typo subfuction
Fix two typos:
 - 'Subfunctons' -> 'Subfunctions'
 - 'subfuction' -> 'subfunction'

Reviewed-by: Joe Damato <joe@dama.to>
Signed-off-by: Ryohei Kinugawa <ryohei.kinugawa@gmail.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://patch.msgid.link/20260324053416.70166-1-ryohei.kinugawa@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-03-26 18:30:47 -07:00
Haiyang Zhang dc3d720e12 net: ethtool: add ethtool COALESCE_RX_CQE_FRAMES/NSECS
Add two parameters for drivers supporting Rx CQE coalescing /
descriptor writeback.

ETHTOOL_A_COALESCE_RX_CQE_FRAMES:
Maximum number of frames that can be coalesced into a CQE or
writeback.

ETHTOOL_A_COALESCE_RX_CQE_NSECS:
Max time in nanoseconds after the first packet arrival in a
coalesced CQE or writeback to be sent.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Link: https://patch.msgid.link/20260317191826.1346111-2-haiyangz@linux.microsoft.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-03-18 20:01:10 -07:00
Jiri Pirko 63fff8c0f7 documentation: networking: add shared devlink documentation
Document shared devlink instances for multiple PFs on the same chip.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Link: https://patch.msgid.link/20260312100407.551173-13-jiri@resnulli.us
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-03-14 13:08:50 -07:00
Simon Baatz 0e24d17bd9 tcp: implement RFC 7323 window retraction receiver requirements
By default, the Linux TCP implementation does not shrink the
advertised window (RFC 7323 calls this "window retraction") with the
following exceptions:

- When an incoming segment cannot be added due to the receive buffer
  running out of memory. Since commit 8c670bdfa5 ("tcp: correct
  handling of extreme memory squeeze") a zero window will be
  advertised in this case. It turns out that reaching the required
  memory pressure is easy when window scaling is in use. In the
  simplest case, sending a sufficient number of segments smaller than
  the scale factor to a receiver that does not read data is enough.

- Commit b650d953cd ("tcp: enforce receive buffer memory limits by
  allowing the tcp window to shrink") addressed the "eating memory"
  problem by introducing a sysctl knob that allows shrinking the
  window before running out of memory.

However, RFC 7323 does not only state that shrinking the window is
necessary in some cases, it also formulates requirements for TCP
implementations when doing so (Section 2.4).

This commit addresses the receiver-side requirements: After retracting
the window, the peer may have a snd_nxt that lies within a previously
advertised window but is now beyond the retracted window. This means
that all incoming segments (including pure ACKs) will be rejected
until the application happens to read enough data to let the peer's
snd_nxt be in window again (which may be never).

To comply with RFC 7323, the receiver MUST honor any segment that
would have been in window for any ACK sent by the receiver and, when
window scaling is in effect, SHOULD track the maximum window sequence
number it has advertised. This patch tracks that maximum window
sequence number rcv_mwnd_seq throughout the connection and uses it in
tcp_sequence() when deciding whether a segment is acceptable.

rcv_mwnd_seq is updated together with rcv_wup and rcv_wnd in
tcp_select_window(). If we count tcp_sequence() as fast path, it is
read in the fast path. Therefore, rcv_mwnd_seq is put into rcv_wnd's
cacheline group.

The logic for handling received data in tcp_data_queue() is already
sufficient and does not need to be updated.

Signed-off-by: Simon Baatz <gmbnomis@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260309-tcp_rfc7323_retract_wnd_rfc-v3-1-4c7f96b1ec69@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-03-14 08:01:49 -07:00
ShravyaPanchagiri 00699d9448 docs: octeontx2: fix typo in documentation
Fix spelling mistake "Crate" to "Create" in the documentation.

Signed-off-by: ShravyaPanchagiri <shravy112@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260311030450.8461-1-shravy112@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-03-12 17:50:57 -07:00
Eric Dumazet 410593fec7 tcp: add sysctl_tcp_shrink_window to netns_ipv4_sysctl.rst
Add missing entry for sysctl_tcp_shrink_window.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260310073855.564927-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-03-11 18:21:08 -07:00
Fernando Fernandez Mancera 7da62262ec inet: add ip_local_port_step_width sysctl to improve port usage distribution
With the current port selection algorithm, ports after a reserved port
range or long time used port are used more often than others [1]. This
causes an uneven port usage distribution. This combines with cloud
environments blocking connections between the application server and the
database server if there was a previous connection with the same source
port, leading to connectivity problems between applications on cloud
environments.

The real issue here is that these firewalls cannot cope with
standards-compliant port reuse. This is a workaround for such situations
and an improvement on the distribution of ports selected.

The proposed solution is to implement a variant of RFC 6056 Algorithm 5.
The step size is selected randomly on every connect() call ensuring it
is a coprime with respect to the size of the range of ports we want to
scan. This way, we can ensure that all ports within the range are
scanned before returning an error. To enable this algorithm, the user
must configure the new sysctl option "net.ipv4.ip_local_port_step_width".

In addition, on graphs generated we can observe that the distribution of
source ports is more even with the proposed approach. [2]

[1] https://0xffsoftware.com/port_graph_current_alg.html

[2] https://0xffsoftware.com/port_graph_random_step_alg.html

Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Link: https://patch.msgid.link/20260309023946.5473-2-fmancera@suse.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-03-10 18:59:39 -07:00
Kyoji Ogasawara aa5ec9d03b net/smc: Add documentation for limit_smc_hs and hs_ctrl
Document missing SMC sysctl parameters limit_smc_hs and hs_ctrl

Signed-off-by: Kyoji Ogasawara <sawara04.o@gmail.com>
Reviewed-by: D. Wythe<alibuda@linux.alibaba.com>
Link: https://patch.msgid.link/20260309124541.22723-3-sawara04.o@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-03-10 17:53:03 -07:00