Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 125 insertions, 0 deletions

diff --git a/Documentation/process/volatile-considered-harmful.rst b/Documentation/process/volatile-considered-harmful.rst
new file mode 100644
index 000000000..7eb6bd7c9
--- /dev/null
+++ b/Documentation/process/volatile-considered-harmful.rst
@@ -0,0 +1,125 @@
+
+.. _volatile_considered_harmful:
+
+Why the "volatile" type class should not be used
+------------------------------------------------
+
+C programmers have often taken volatile to mean that the variable could be
+changed outside of the current thread of execution; as a result, they are
+sometimes tempted to use it in kernel code when shared data structures are
+being used.  In other words, they have been known to treat volatile types
+as a sort of easy atomic variable, which they are not.  The use of volatile in
+kernel code is almost never correct; this document describes why.
+
+The key point to understand with regard to volatile is that its purpose is
+to suppress optimization, which is almost never what one really wants to
+do.  In the kernel, one must protect shared data structures against
+unwanted concurrent access, which is very much a different task.  The
+process of protecting against unwanted concurrency will also avoid almost
+all optimization-related problems in a more efficient way.
+
+Like volatile, the kernel primitives which make concurrent access to data
+safe (spinlocks, mutexes, memory barriers, etc.) are designed to prevent
+unwanted optimization.  If they are being used properly, there will be no
+need to use volatile as well.  If volatile is still necessary, there is
+almost certainly a bug in the code somewhere.  In properly-written kernel
+code, volatile can only serve to slow things down.
+
+Consider a typical block of kernel code::
+
+    spin_lock(&the_lock);
+    do_something_on(&shared_data);
+    do_something_else_with(&shared_data);
+    spin_unlock(&the_lock);
+
+If all the code follows the locking rules, the value of shared_data cannot
+change unexpectedly while the_lock is held.  Any other code which might
+want to play with that data will be waiting on the lock.  The spinlock
+primitives act as memory barriers - they are explicitly written to do so -
+meaning that data accesses will not be optimized across them.  So the
+compiler might think it knows what will be in shared_data, but the
+spin_lock() call, since it acts as a memory barrier, will force it to
+forget anything it knows.  There will be no optimization problems with
+accesses to that data.
+
+If shared_data were declared volatile, the locking would still be
+necessary.  But the compiler would also be prevented from optimizing access
+to shared_data _within_ the critical section, when we know that nobody else
+can be working with it.  While the lock is held, shared_data is not
+volatile.  When dealing with shared data, proper locking makes volatile
+unnecessary - and potentially harmful.
+
+The volatile storage class was originally meant for memory-mapped I/O
+registers.  Within the kernel, register accesses, too, should be protected
+by locks, but one also does not want the compiler "optimizing" register
+accesses within a critical section.  But, within the kernel, I/O memory
+accesses are always done through accessor functions; accessing I/O memory
+directly through pointers is frowned upon and does not work on all
+architectures.  Those accessors are written to prevent unwanted
+optimization, so, once again, volatile is unnecessary.
+
+Another situation where one might be tempted to use volatile is
+when the processor is busy-waiting on the value of a variable.  The right
+way to perform a busy wait is::
+
+    while (my_variable != what_i_want)
+        cpu_relax();
+
+The cpu_relax() call can lower CPU power consumption or yield to a
+hyperthreaded twin processor; it also happens to serve as a compiler
+barrier, so, once again, volatile is unnecessary.  Of course, busy-
+waiting is generally an anti-social act to begin with.
+
+There are still a few rare situations where volatile makes sense in the
+kernel:
+
+  - The above-mentioned accessor functions might use volatile on
+    architectures where direct I/O memory access does work.  Essentially,
+    each accessor call becomes a little critical section on its own and
+    ensures that the access happens as expected by the programmer.
+
+  - Inline assembly code which changes memory, but which has no other
+    visible side effects, risks being deleted by GCC.  Adding the volatile
+    keyword to asm statements will prevent this removal.
+
+  - The jiffies variable is special in that it can have a different value
+    every time it is referenced, but it can be read without any special
+    locking.  So jiffies can be volatile, but the addition of other
+    variables of this type is strongly frowned upon.  Jiffies is considered
+    to be a "stupid legacy" issue (Linus's words) in this regard; fixing it
+    would be more trouble than it is worth.
+
+  - Pointers to data structures in coherent memory which might be modified
+    by I/O devices can, sometimes, legitimately be volatile.  A ring buffer
+    used by a network adapter, where that adapter changes pointers to
+    indicate which descriptors have been processed, is an example of this
+    type of situation.
+
+For most code, none of the above justifications for volatile apply.  As a
+result, the use of volatile is likely to be seen as a bug and will bring
+additional scrutiny to the code.  Developers who are tempted to use
+volatile should take a step back and think about what they are truly trying
+to accomplish.
+
+Patches to remove volatile variables are generally welcome - as long as
+they come with a justification which shows that the concurrency issues have
+been properly thought through.
+
+
+References
+==========
+
+[1] https://lwn.net/Articles/233481/
+
+[2] https://lwn.net/Articles/233482/
+
+Credits
+=======
+
+Original impetus and research by Randy Dunlap
+
+Written by Jonathan Corbet
+
+Improvements via comments from Satyam Sharma, Johannes Stezenbach, Jesper
+Juhl, Heikki Orsila, H. Peter Anvin, Philipp Hahn, and Stefan
+Richter.