When a user port has a label in device tree, the corresponding
netdevice is, to quote include/uapi/linux/netdevice.h, "predictably
named by the kernel". This is also explicitly one of the intended use
cases for NET_NAME_PREDICTABLE, quoting 685343fc ("net: add
name_assign_type netdev attribute"):

  NET_NAME_PREDICTABLE:
    The ifname has been assigned by the kernel in a predictable way
    [...] Examples include [...] and names deduced from hardware
    properties (including being given explicitly by the firmware).

Expose that information properly for the benefit of userspace tools
that make decisions based on the name_assign_type attribute,
e.g. a systemd-udev rule with "kernel" in NamePolicy.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.faineli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The following two patches each have a (small) chance of causing
regressions for userspace and will in that case of course need to be
reverted.

In order to prepare for that and make those two patches independent
and individually revertable, refactor the code which sets the names
for user ports by moving the "fall back to eth%d if no label is given
in device tree" to dsa_slave_create().

No functional change (at least none intended).
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.faineli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Many of the drivers which implement ethtool_ops::get_drvinfo() will
prints the .driver, .version or .bus_info of struct ethtool_drvinfo.
To have a glance of current state, do:

  $ git grep -W "get_drvinfo(struct"

Printing in those three fields is useless because:

  - since [1], the driver version should be the kernel version (at
    least for upstream drivers). Arguably, out of tree drivers might
    still want to set a custom version, but out of tree is not our
    focus.

  - since [2], the core is able to provide default values for .driver
    and .bus_info.

In summary, drivers may provide .fw_version and .erom_version, the
rest is expected to be done by the core.

In struct ethtool_ops doc from linux/ethtool: rephrase field
get_drvinfo() doc to discourage developers from implementing this
callback.

In struct ethtool_drvinfo doc from uapi/linux/ethtool.h: remove the
paragraph mentioning what drivers should do. Rationale: no need to
repeat what is already written in struct ethtool_ops doc. But add a
note that .fw_version and .erom_version are driver defined.

Also update the dummy driver and simply remove the callback in order
not to confuse the newcomers: most of the drivers will not need this
callback function any more.

[1] commit 6a7e25c7 ("net/core: Replace driver version to be
    kernel version")
Link: https://git.kernel.org/torvalds/linux/c/6a7e25c7fb48

[2] commit edaf5df2 ("ethtool: ethtool_get_drvinfo: populate
    drvinfo fields even if callback exits")
Link: https://git.kernel.org/netdev/net-next/c/edaf5df22cb8Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/r/20221116171828.4093-1-mailhol.vincent@wanadoo.frSigned-off-by: Jakub Kicinski <kuba@kernel.org>

include/linux/bpf.h
  1f6e04a1 ("bpf: Fix offset calculation error in __copy_map_value and zero_map_value")
  aa3496ac ("bpf: Refactor kptr_off_tab into btf_record")
  f71b2f64 ("bpf: Refactor map->off_arr handling")
https://lore.kernel.org/all/20221114095000.67a73239@canb.auug.org.au/Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Pull networking fixes from Paolo Abeni:
 "Including fixes from bpf.

  Current release - regressions:

   - tls: fix memory leak in tls_enc_skb() and tls_sw_fallback_init()

  Previous releases - regressions:

   - bridge: fix memory leaks when changing VLAN protocol

   - dsa: make dsa_master_ioctl() see through port_hwtstamp_get() shims

   - dsa: don't leak tagger-owned storage on switch driver unbind

   - eth: mlxsw: avoid warnings when not offloaded FDB entry with IPv6
     is removed

   - eth: stmmac: ensure tx function is not running in
     stmmac_xdp_release()

   - eth: hns3: fix return value check bug of rx copybreak

  Previous releases - always broken:

   - kcm: close race conditions on sk_receive_queue

   - bpf: fix alignment problem in bpf_prog_test_run_skb()

   - bpf: fix writing offset in case of fault in
     strncpy_from_kernel_nofault

   - eth: macvlan: use built-in RCU list checking

   - eth: marvell: add sleep time after enabling the loopback bit

   - eth: octeon_ep: fix potential memory leak in octep_device_setup()

  Misc:

   - tcp: configurable source port perturb table size

   - bpf: Convert BPF_DISPATCHER to use static_call() (not ftrace)"

* tag 'net-6.1-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (51 commits)
  net: use struct_group to copy ip/ipv6 header addresses
  net: usb: smsc95xx: fix external PHY reset
  net: usb: qmi_wwan: add Telit 0x103a composition
  netdevsim: Fix memory leak of nsim_dev->fa_cookie
  tcp: configurable source port perturb table size
  l2tp: Serialize access to sk_user_data with sk_callback_lock
  net: thunderbolt: Fix error handling in tbnet_init()
  net: microchip: sparx5: Fix potential null-ptr-deref in sparx_stats_init() and sparx5_start()
  net: lan966x: Fix potential null-ptr-deref in lan966x_stats_init()
  net: dsa: don't leak tagger-owned storage on switch driver unbind
  net/x25: Fix skb leak in x25_lapb_receive_frame()
  net: ag71xx: call phylink_disconnect_phy if ag71xx_hw_enable() fail in ag71xx_open()
  bridge: switchdev: Fix memory leaks when changing VLAN protocol
  net: hns3: fix setting incorrect phy link ksettings for firmware in resetting process
  net: hns3: fix return value check bug of rx copybreak
  net: hns3: fix incorrect hw rss hash type of rx packet
  net: phy: marvell: add sleep time after enabling the loopback bit
  net: ena: Fix error handling in ena_init()
  kcm: close race conditions on sk_receive_queue
  net: ionic: Fix error handling in ionic_init_module()
  ...

The rswitch_etha_wait_link_verification() is supposed to return zero
on success or negative error codes.  Unfortunately it is declared as a
bool so the caller treats everything as success.

Fixes: 3590918b ("net: ethernet: renesas: Add support for "Ethernet Switch"")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/Y3OPo6AOL6PTvXFU@kiliSigned-off-by: Paolo Abeni <pabeni@redhat.com>

The current virtual nci driver is great for testing and fuzzing.
But it allows to create at most one "global" device which does not allow
to run parallel tests and harms fuzzing isolation and reproducibility.
Restructure the driver to allow creation of multiple independent devices.
This should be backwards compatible for existing tests.
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Bongsu Jeon <bongsu.jeon@samsung.com>
Cc: Bongsu Jeon <bongsu.jeon@samsung.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: netdev@vger.kernel.org
Link: https://lore.kernel.org/r/20221115100017.787929-1-dvyukov@google.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

Variable cnt is just being incremented and it's never used
anywhere else. The variable and the increment are redundant so
remove it.
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Link: https://lore.kernel.org/r/20221115093137.144002-1-colin.i.king@gmail.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

The subh.addip_hdr pointer is also of type (struct sctp_addiphdr *), so
it does not require a cast.
Signed-off-by: Li zeming <zeming@nfschina.com>
Link: https://lore.kernel.org/r/20221115020705.3220-1-zeming@nfschina.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

kernel test robot reported warnings when build bonding module with
make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/net/bonding/:

                 from ../drivers/net/bonding/bond_main.c:35:
In function ‘fortify_memcpy_chk’,
    inlined from ‘iph_to_flow_copy_v4addrs’ at ../include/net/ip.h:566:2,
    inlined from ‘bond_flow_ip’ at ../drivers/net/bonding/bond_main.c:3984:3:
../include/linux/fortify-string.h:413:25: warning: call to ‘__read_overflow2_field’ declared with attribute warning: detected read beyond size of f
ield (2nd parameter); maybe use struct_group()? [-Wattribute-warning]
  413 |                         __read_overflow2_field(q_size_field, size);
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘fortify_memcpy_chk’,
    inlined from ‘iph_to_flow_copy_v6addrs’ at ../include/net/ipv6.h:900:2,
    inlined from ‘bond_flow_ip’ at ../drivers/net/bonding/bond_main.c:3994:3:
../include/linux/fortify-string.h:413:25: warning: call to ‘__read_overflow2_field’ declared with attribute warning: detected read beyond size of f
ield (2nd parameter); maybe use struct_group()? [-Wattribute-warning]
  413 |                         __read_overflow2_field(q_size_field, size);
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is because we try to copy the whole ip/ip6 address to the flow_key,
while we only point the to ip/ip6 saddr. Note that since these are UAPI
headers, __struct_group() is used to avoid the compiler warnings.
Reported-by: kernel test robot <lkp@intel.com>
Fixes: c3f83241 ("net: Add full IPv6 addresses to flow_keys")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://lore.kernel.org/r/20221115142400.1204786-1-liuhangbin@gmail.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

An external PHY needs settling time after power up or reset.
In the bind() function an mdio bus is registered. If at this point
the external PHY is still initialising, no valid PHY ID will be
read and on phy_find_first() the bind() function will fail.

If an external PHY is present, wait the maximum time specified
in 802.3 45.2.7.1.1.

Fixes: 05b35e7e ("smsc95xx: add phylib support")
Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20221115114434.9991-2-alexandru.tachici@analog.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

Add the following Telit LE910C4-WWX composition:

0x103a: rmnet
Signed-off-by: Enrico Sau <enrico.sau@gmail.com>
Acked-by: Bjørn Mork <bjorn@mork.no>
Link: https://lore.kernel.org/r/20221115105859.14324-1-enrico.sau@gmail.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

kmemleak reports this issue:

unreferenced object 0xffff8881bac872d0 (size 8):
  comm "sh", pid 58603, jiffies 4481524462 (age 68.065s)
  hex dump (first 8 bytes):
    04 00 00 00 de ad be ef                          ........
  backtrace:
    [<00000000c80b8577>] __kmalloc+0x49/0x150
    [<000000005292b8c6>] nsim_dev_trap_fa_cookie_write+0xc1/0x210 [netdevsim]
    [<0000000093d78e77>] full_proxy_write+0xf3/0x180
    [<000000005a662c16>] vfs_write+0x1c5/0xaf0
    [<000000007aabf84a>] ksys_write+0xed/0x1c0
    [<000000005f1d2e47>] do_syscall_64+0x3b/0x90
    [<000000006001c6ec>] entry_SYSCALL_64_after_hwframe+0x63/0xcd

The issue occurs in the following scenarios:

nsim_dev_trap_fa_cookie_write()
  kmalloc() fa_cookie
  nsim_dev->fa_cookie = fa_cookie
..
nsim_drv_remove()

The fa_cookie allocked in nsim_dev_trap_fa_cookie_write() is not freed. To
fix, add kfree(nsim_dev->fa_cookie) to nsim_drv_remove().

Fixes: d3cbb907 ("netdevsim: add ACL trap reporting cookie as a metadata")
Signed-off-by: Wang Yufen <wangyufen@huawei.com>
Cc: Jiri Pirko <jiri@mellanox.com>
Link: https://lore.kernel.org/r/1668504625-14698-1-git-send-email-wangyufen@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

The mlxsw adjfine implementation in the spectrum_ptp.c file converts
scaled_ppm into ppb before updating a cyclecounter multiplier using the
standard "base * ppb / 1billion" calculation.

This can be re-written to use adjust_by_scaled_ppm, directly using the
scaled parts per million and reducing the amount of code required to
express this calculation.

We still calculate the parts per billion for passing into
mlxsw_sp_ptp_phc_adjfreq because this function requires the input to be in
parts per billion.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Cc: Amit Cohen <amcohen@nvidia.com>
Cc: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Tested-by: Ido Schimmel <idosch@nvidia.com>
Link: https://lore.kernel.org/r/20221114213701.815132-1-jacob.e.keller@intel.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Pull xen fixes from Juergen Gross:
 "Two trivial cleanups, and three simple fixes"

* tag 'for-linus-6.1-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/platform-pci: use define instead of literal number
  xen/platform-pci: add missing free_irq() in error path
  xen-pciback: Allow setting PCI_MSIX_FLAGS_MASKALL too
  xen/pcpu: fix possible memory leak in register_pcpu()
  x86/xen: Use kstrtobool() instead of strtobool()

Pull pin control fixes from Linus Walleij:
 "Aere is a hopefully final round of pin control fixes. Nothing special,
  driver fixes and we caught a potential NULL pointer exception.

   - Fix a potential NULL dereference in the core!

   - Fix all pin mux routes in the Rockchop PX30 driver

   - Fix the UFS pins in the Qualcomm SC8280XP driver

   - Fix bias disabling in the Mediatek driver

   - Fix debounce time settings in the Mediatek driver"

* tag 'pinctrl-v6.1-4' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: mediatek: Export debounce time tables
  pinctrl: mediatek: Fix EINT pins input debounce time configuration
  pinctrl: devicetree: fix null pointer dereferencing in pinctrl_dt_to_map
  pinctrl: mediatek: common-v2: Fix bias-disable for PULL_PU_PD_RSEL_TYPE
  pinctrl: qcom: sc8280xp: Rectify UFS reset pins
  pinctrl: rockchip: list all pins in a possible mux route for PX30

Merge tag 'platform-drivers-x86-v6.1-4' of git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86

Pull x86 platform driver fixes from Hans de Goede:

 - Surface Pro 9 and Surface Laptop 5 kbd, battery, etc support (this
   is just a few hw-id additions)

 - A couple of other hw-id / DMI-quirk additions

 - A few small bug fixes + 1 build fix

* tag 'platform-drivers-x86-v6.1-4' of git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86:
  platform/x86: ideapad-laptop: Add module parameters to match DMI quirk tables
  platform/x86: ideapad-laptop: Fix interrupt storm on fn-lock toggle on some Yoga laptops
  platform/x86: hp-wmi: Ignore Smart Experience App event
  platform/surface: aggregator_registry: Add support for Surface Laptop 5
  platform/surface: aggregator_registry: Add support for Surface Pro 9
  platform/surface: aggregator: Do not check for repeated unsequenced packets
  platform/x86: acer-wmi: Enable SW_TABLET_MODE on Switch V 10 (SW5-017)
  platform/x86: asus-wmi: add missing pci_dev_put() in asus_wmi_set_xusb2pr()
  platform/x86/intel: pmc: Don't unconditionally attach Intel PMC when virtualized
  platform/x86: thinkpad_acpi: Enable s2idle quirk for 21A1 machine type
  platform/x86/amd: pmc: Add new ACPI ID AMDI0009
  platform/x86/amd: pmc: Remove more CONFIG_DEBUG_FS checks

Annotate the lockless read of queue->synflood_warned.

Following xchg() has the needed data-race resolution.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The valptr pointer is of (void *) type, so other pointers need not be
forced to assign values to it.
Signed-off-by: Li zeming <zeming@nfschina.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

On embedded systems with little memory and no relevant
security concerns, it is beneficial to reduce the size
of the table.

Reducing the size from 2^16 to 2^8 saves 255 KiB
of kernel RAM.

Makes the table size configurable as an expert option.

The size was previously increased from 2^8 to 2^16
in commit 4c2c8f03 ("tcp: increase source port perturb table to
2^16").
Signed-off-by: Gleb Mazovetskiy <glex.spb@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

sk->sk_user_data has multiple users, which are not compatible with each
other. Writers must synchronize by grabbing the sk->sk_callback_lock.

l2tp currently fails to grab the lock when modifying the underlying tunnel
socket fields. Fix it by adding appropriate locking.

We err on the side of safety and grab the sk_callback_lock also inside the
sk_destruct callback overridden by l2tp, even though there should be no
refs allowing access to the sock at the time when sk_destruct gets called.

v4:
- serialize write to sk_user_data in l2tp sk_destruct

v3:
- switch from sock lock to sk_callback_lock
- document write-protection for sk_user_data

v2:
- update Fixes to point to origin of the bug
- use real names in Reported/Tested-by tags

Cc: Tom Parkin <tparkin@katalix.com>
Fixes: 3557baab ("[L2TP]: PPP over L2TP driver core")
Reported-by: Haowei Yan <g1042620637@gmail.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Eric Dumazet says:

====================
net: add atomic dev->stats infra

Long standing KCSAN issues are caused by data-race around
some dev->stats changes.

Most performance critical paths already use per-cpu
variables, or per-queue ones.

It is reasonable (and more correct) to use atomic operations
for the slow paths.

First patch adds the infrastructure, then three patches address
the most common paths that syzbot is playing with.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Most of code paths in tunnels are lockless (eg NETIF_F_LLTX in tx).

Adopt SMP safe DEV_STATS_INC() to update dev->stats fields.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Most of code paths in tunnels are lockless (eg NETIF_F_LLTX in tx).

Adopt SMP safe DEV_STATS_{INC|ADD}() to update dev->stats fields.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

syzbot/KCSAN reported that multiple cpus are updating dev->stats.tx_error
concurrently.

This is because sit tunnels are NETIF_F_LLTX, meaning their ndo_start_xmit()
is not protected by a spinlock.

While original KCSAN report was about tx path, rx path has the same issue.
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Long standing KCSAN issues are caused by data-race around
some dev->stats changes.

Most performance critical paths already use per-cpu
variables, or per-queue ones.

It is reasonable (and more correct) to use atomic operations
for the slow paths.

This patch adds an union for each field of net_device_stats,
so that we can convert paths that are not yet protected
by a spinlock or a mutex.

netdev_stats_to_stats64() no longer has an #if BITS_PER_LONG==64

Note that the memcpy() we were using on 64bit arches
had no provision to avoid load-tearing,
while atomic_long_read() is providing the needed protection
at no cost.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Eric Dumazet says:

====================
net: more try_cmpxchg() conversions

Adopt try_cmpxchg() and friends in more places, as this
is preferred nowadays.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Adopt atomic64_try_cmpxchg() and remove the loop,
to make the intent more obvious.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

This makes code a bit cleaner.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

This makes the code slightly more efficient.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Adopting atomic_try_cmpxchg() makes the code cleaner.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Adopt atomic_try_cmpxchg() which is slightly more efficient.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Adopt atomic_long_try_cmpxchg() in mm_account_pinned_pages()
as it is slightly more efficient.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

RFC 2863 says:

   The lowerLayerDown state is also a refinement on the down state.
   This new state indicates that this interface runs "on top of" one or
   more other interfaces (see ifStackTable) and that this interface is
   down specifically because one or more of these lower-layer interfaces
   are down.

DSA interfaces are virtual network devices, stacked on top of the DSA
master, but they have a physical MAC, with a PHY that reports a real
link status.

But since DSA (perhaps improperly) uses an iflink to describe the
relationship to its master since commit c0840801 ("dsa: set ->iflink
on slave interfaces to the ifindex of the parent"), default_operstate()
will misinterpret this to mean that every time the carrier of a DSA
interface is not ok, it is because of the master being not ok.

In fact, since commit c0a8a9c2 ("net: dsa: automatically bring user
ports down when master goes down"), DSA cannot even in theory be in the
lowerLayerDown state, because it just calls dev_close_many(), thereby
going down, when the master goes down.

We could revert the commit that creates an iflink between a DSA user
port and its master, especially since now we have an alternative
IFLA_DSA_MASTER which has less side effects. But there may be tooling in
use which relies on the iflink, which has existed since 2009.

We could also probably do something local within DSA to overwrite what
rfc2863_policy() did, in a way similar to hsr_set_operstate(), but this
seems like a hack.

What seems appropriate is to follow the iflink, and check the carrier
status of that interface as well. If that's down too, yes, keep
reporting lowerLayerDown, otherwise just down.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Kuniyuki Iwashima says:

====================
udp: Introduce optional per-netns hash table.

This series is the UDP version of the per-netns ehash series [0],
which were initially in the same patch set. [1]

The notable difference with TCP is the max table size is 64K and the min
size is 128.  This is because the possible hash range by udp_hashfn()
always fits in 64K within the same netns and because we want to keep a
bitmap in udp_lib_get_port() on the stack.  Also, the UDP per-netns table
isolates both 1-tuple and 2-tuple tables.

For details, please see the last patch.

  patch 1 - 4: prep for per-netns hash table
  patch     5: add per-netns hash table

[0]: https://lore.kernel.org/netdev/20220908011022.45342-1-kuniyu@amazon.com/
[1]: https://lore.kernel.org/netdev/20220826000445.46552-1-kuniyu@amazon.com/
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

The maximum hash table size is 64K due to the nature of the protocol. [0]
It's smaller than TCP, and fewer sockets can cause a performance drop.

On an EC2 c5.24xlarge instance (192 GiB memory), after running iperf3 in
different netns, creating 32Mi sockets without data transfer in the root
netns causes regression for the iperf3's connection.

  uhash_entries		sockets		length		Gbps
	    64K		      1		     1		5.69
			    1Mi		    16		5.27
			    2Mi		    32		4.90
			    4Mi		    64		4.09
			    8Mi		   128		2.96
			   16Mi		   256		2.06
			   32Mi		   512		1.12

The per-netns hash table breaks the lengthy lists into shorter ones.  It is
useful on a multi-tenant system with thousands of netns.  With smaller hash
tables, we can look up sockets faster, isolate noisy neighbours, and reduce
lock contention.

The max size of the per-netns table is 64K as well.  This is because the
possible hash range by udp_hashfn() always fits in 64K within the same
netns and we cannot make full use of the whole buckets larger than 64K.

  /* 0 < num < 64K  ->  X < hash < X + 64K */
  (num + net_hash_mix(net)) & mask;

Also, the min size is 128.  We use a bitmap to search for an available
port in udp_lib_get_port().  To keep the bitmap on the stack and not
fire the CONFIG_FRAME_WARN error at build time, we round up the table
size to 128.

The sysctl usage is the same with TCP:

  $ dmesg | cut -d ' ' -f 6- | grep "UDP hash"
  UDP hash table entries: 65536 (order: 9, 2097152 bytes, vmalloc)

  # sysctl net.ipv4.udp_hash_entries
  net.ipv4.udp_hash_entries = 65536  # can be changed by uhash_entries

  # sysctl net.ipv4.udp_child_hash_entries
  net.ipv4.udp_child_hash_entries = 0  # disabled by default

  # ip netns add test1
  # ip netns exec test1 sysctl net.ipv4.udp_hash_entries
  net.ipv4.udp_hash_entries = -65536  # share the global table

  # sysctl -w net.ipv4.udp_child_hash_entries=100
  net.ipv4.udp_child_hash_entries = 100

  # ip netns add test2
  # ip netns exec test2 sysctl net.ipv4.udp_hash_entries
  net.ipv4.udp_hash_entries = 128  # own a per-netns table with 2^n buckets

We could optimise the hash table lookup/iteration further by removing
the netns comparison for the per-netns one in the future.  Also, we
could optimise the sparse udp_hslot layout by putting it in udp_table.

[0]: https://lore.kernel.org/netdev/4ACC2815.7010101@gmail.com/Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

We will soon introduce an optional per-netns hash table
for UDP.

This means we cannot use udp_table directly in most places.

Instead, access it via net->ipv4.udp_table.

The access will be valid only while initialising udp_table
itself and creating/destroying each netns.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

We will soon introduce an optional per-netns hash table
for UDP.

This means we cannot use the global udp_seq_afinfo.udp_table
to fetch a UDP hash table.

Instead, set NULL to udp_seq_afinfo.udp_table for UDP and get
a proper table from net->ipv4.udp_table.

Note that we still need udp_seq_afinfo.udp_table for UDP LITE.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

We will soon introduce an optional per-netns hash table
for UDP.

This means we cannot use the global sk->sk_prot->h.udp_table
to fetch a UDP hash table.

Instead, set NULL to sk->sk_prot->h.udp_table for UDP and get
a proper table from net->ipv4.udp_table.

Note that we still need sk->sk_prot->h.udp_table for UDP LITE.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

This patch adds no functional change and cleans up some functions
that the following patches touch around so that we make them tidy
and easy to review/revert.  The change is mainly to keep reverse
christmas tree order.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>