From 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 21 Feb 2023 18:24:12 -0800 Subject: Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 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(). ... --- Documentation/watchdog/watchdog-api.rst | 271 ++++++++++++++++++++++++++++++++ 1 file changed, 271 insertions(+) create mode 100644 Documentation/watchdog/watchdog-api.rst (limited to 'Documentation/watchdog/watchdog-api.rst') diff --git a/Documentation/watchdog/watchdog-api.rst b/Documentation/watchdog/watchdog-api.rst new file mode 100644 index 000000000..800dcd758 --- /dev/null +++ b/Documentation/watchdog/watchdog-api.rst @@ -0,0 +1,271 @@ +============================= +The Linux Watchdog driver API +============================= + +Last reviewed: 10/05/2007 + + + +Copyright 2002 Christer Weingel + +Some parts of this document are copied verbatim from the sbc60xxwdt +driver which is (c) Copyright 2000 Jakob Oestergaard + +This document describes the state of the Linux 2.4.18 kernel. + +Introduction +============ + +A Watchdog Timer (WDT) is a hardware circuit that can reset the +computer system in case of a software fault. You probably knew that +already. + +Usually a userspace daemon will notify the kernel watchdog driver via the +/dev/watchdog special device file that userspace is still alive, at +regular intervals. When such a notification occurs, the driver will +usually tell the hardware watchdog that everything is in order, and +that the watchdog should wait for yet another little while to reset +the system. If userspace fails (RAM error, kernel bug, whatever), the +notifications cease to occur, and the hardware watchdog will reset the +system (causing a reboot) after the timeout occurs. + +The Linux watchdog API is a rather ad-hoc construction and different +drivers implement different, and sometimes incompatible, parts of it. +This file is an attempt to document the existing usage and allow +future driver writers to use it as a reference. + +The simplest API +================ + +All drivers support the basic mode of operation, where the watchdog +activates as soon as /dev/watchdog is opened and will reboot unless +the watchdog is pinged within a certain time, this time is called the +timeout or margin. The simplest way to ping the watchdog is to write +some data to the device. So a very simple watchdog daemon would look +like this source file: see samples/watchdog/watchdog-simple.c + +A more advanced driver could for example check that a HTTP server is +still responding before doing the write call to ping the watchdog. + +When the device is closed, the watchdog is disabled, unless the "Magic +Close" feature is supported (see below). This is not always such a +good idea, since if there is a bug in the watchdog daemon and it +crashes the system will not reboot. Because of this, some of the +drivers support the configuration option "Disable watchdog shutdown on +close", CONFIG_WATCHDOG_NOWAYOUT. If it is set to Y when compiling +the kernel, there is no way of disabling the watchdog once it has been +started. So, if the watchdog daemon crashes, the system will reboot +after the timeout has passed. Watchdog devices also usually support +the nowayout module parameter so that this option can be controlled at +runtime. + +Magic Close feature +=================== + +If a driver supports "Magic Close", the driver will not disable the +watchdog unless a specific magic character 'V' has been sent to +/dev/watchdog just before closing the file. If the userspace daemon +closes the file without sending this special character, the driver +will assume that the daemon (and userspace in general) died, and will +stop pinging the watchdog without disabling it first. This will then +cause a reboot if the watchdog is not re-opened in sufficient time. + +The ioctl API +============= + +All conforming drivers also support an ioctl API. + +Pinging the watchdog using an ioctl: + +All drivers that have an ioctl interface support at least one ioctl, +KEEPALIVE. This ioctl does exactly the same thing as a write to the +watchdog device, so the main loop in the above program could be +replaced with:: + + while (1) { + ioctl(fd, WDIOC_KEEPALIVE, 0); + sleep(10); + } + +the argument to the ioctl is ignored. + +Setting and getting the timeout +=============================== + +For some drivers it is possible to modify the watchdog timeout on the +fly with the SETTIMEOUT ioctl, those drivers have the WDIOF_SETTIMEOUT +flag set in their option field. The argument is an integer +representing the timeout in seconds. The driver returns the real +timeout used in the same variable, and this timeout might differ from +the requested one due to limitation of the hardware:: + + int timeout = 45; + ioctl(fd, WDIOC_SETTIMEOUT, &timeout); + printf("The timeout was set to %d seconds\n", timeout); + +This example might actually print "The timeout was set to 60 seconds" +if the device has a granularity of minutes for its timeout. + +Starting with the Linux 2.4.18 kernel, it is possible to query the +current timeout using the GETTIMEOUT ioctl:: + + ioctl(fd, WDIOC_GETTIMEOUT, &timeout); + printf("The timeout was is %d seconds\n", timeout); + +Pretimeouts +=========== + +Some watchdog timers can be set to have a trigger go off before the +actual time they will reset the system. This can be done with an NMI, +interrupt, or other mechanism. This allows Linux to record useful +information (like panic information and kernel coredumps) before it +resets:: + + pretimeout = 10; + ioctl(fd, WDIOC_SETPRETIMEOUT, &pretimeout); + +Note that the pretimeout is the number of seconds before the time +when the timeout will go off. It is not the number of seconds until +the pretimeout. So, for instance, if you set the timeout to 60 seconds +and the pretimeout to 10 seconds, the pretimeout will go off in 50 +seconds. Setting a pretimeout to zero disables it. + +There is also a get function for getting the pretimeout:: + + ioctl(fd, WDIOC_GETPRETIMEOUT, &timeout); + printf("The pretimeout was is %d seconds\n", timeout); + +Not all watchdog drivers will support a pretimeout. + +Get the number of seconds before reboot +======================================= + +Some watchdog drivers have the ability to report the remaining time +before the system will reboot. The WDIOC_GETTIMELEFT is the ioctl +that returns the number of seconds before reboot:: + + ioctl(fd, WDIOC_GETTIMELEFT, &timeleft); + printf("The timeout was is %d seconds\n", timeleft); + +Environmental monitoring +======================== + +All watchdog drivers are required return more information about the system, +some do temperature, fan and power level monitoring, some can tell you +the reason for the last reboot of the system. The GETSUPPORT ioctl is +available to ask what the device can do:: + + struct watchdog_info ident; + ioctl(fd, WDIOC_GETSUPPORT, &ident); + +the fields returned in the ident struct are: + + ================ ============================================= + identity a string identifying the watchdog driver + firmware_version the firmware version of the card if available + options a flags describing what the device supports + ================ ============================================= + +the options field can have the following bits set, and describes what +kind of information that the GET_STATUS and GET_BOOT_STATUS ioctls can +return. + + ================ ========================= + WDIOF_OVERHEAT Reset due to CPU overheat + ================ ========================= + +The machine was last rebooted by the watchdog because the thermal limit was +exceeded: + + ============== ========== + WDIOF_FANFAULT Fan failed + ============== ========== + +A system fan monitored by the watchdog card has failed + + ============= ================ + WDIOF_EXTERN1 External relay 1 + ============= ================ + +External monitoring relay/source 1 was triggered. Controllers intended for +real world applications include external monitoring pins that will trigger +a reset. + + ============= ================ + WDIOF_EXTERN2 External relay 2 + ============= ================ + +External monitoring relay/source 2 was triggered + + ================ ===================== + WDIOF_POWERUNDER Power bad/power fault + ================ ===================== + +The machine is showing an undervoltage status + + =============== ============================= + WDIOF_CARDRESET Card previously reset the CPU + =============== ============================= + +The last reboot was caused by the watchdog card + + ================ ===================== + WDIOF_POWEROVER Power over voltage + ================ ===================== + +The machine is showing an overvoltage status. Note that if one level is +under and one over both bits will be set - this may seem odd but makes +sense. + + =================== ===================== + WDIOF_KEEPALIVEPING Keep alive ping reply + =================== ===================== + +The watchdog saw a keepalive ping since it was last queried. + + ================ ======================= + WDIOF_SETTIMEOUT Can set/get the timeout + ================ ======================= + +The watchdog can do pretimeouts. + + ================ ================================ + WDIOF_PRETIMEOUT Pretimeout (in seconds), get/set + ================ ================================ + + +For those drivers that return any bits set in the option field, the +GETSTATUS and GETBOOTSTATUS ioctls can be used to ask for the current +status, and the status at the last reboot, respectively:: + + int flags; + ioctl(fd, WDIOC_GETSTATUS, &flags); + + or + + ioctl(fd, WDIOC_GETBOOTSTATUS, &flags); + +Note that not all devices support these two calls, and some only +support the GETBOOTSTATUS call. + +Some drivers can measure the temperature using the GETTEMP ioctl. The +returned value is the temperature in degrees fahrenheit:: + + int temperature; + ioctl(fd, WDIOC_GETTEMP, &temperature); + +Finally the SETOPTIONS ioctl can be used to control some aspects of +the cards operation:: + + int options = 0; + ioctl(fd, WDIOC_SETOPTIONS, &options); + +The following options are available: + + ================= ================================ + WDIOS_DISABLECARD Turn off the watchdog timer + WDIOS_ENABLECARD Turn on the watchdog timer + WDIOS_TEMPPANIC Kernel panic on temperature trip + ================= ================================ + +[FIXME -- better explanations] -- cgit v1.2.3