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authorLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
committerLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
commit5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch)
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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(). ...
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+.. include:: ../disclaimer-zh_CN.rst
+
+:Original: Documentation/core-api/local_ops.rst
+
+:翻译:
+
+ 司延腾 Yanteng Si <siyanteng@loongson.cn>
+
+.. _cn_local_ops:
+
+========================
+本地原子操作的语义和行为
+========================
+
+:作者: Mathieu Desnoyers
+
+
+本文解释了本地原子操作的目的,如何为任何给定的架构实现这些操作,并说明了
+如何正确使用这些操作。它还强调了在内存写入顺序很重要的情况下,跨CPU读取
+这些本地变量时必须采取的预防措施。
+
+.. note::
+
+ 注意,基于 ``local_t`` 的操作不建议用于一般内核操作。请使用 ``this_cpu``
+ 操作来代替使用,除非真的有特殊目的。大多数内核中使用的 ``local_t`` 已
+ 经被 ``this_cpu`` 操作所取代。 ``this_cpu`` 操作在一条指令中结合了重
+ 定位和类似 ``local_t`` 的语义,产生了更紧凑和更快的执行代码。
+
+
+本地原子操作的目的
+==================
+
+本地原子操作的目的是提供快速和高度可重入的每CPU计数器。它们通过移除LOCK前
+缀和通常需要在CPU间同步的内存屏障,将标准原子操作的性能成本降到最低。
+
+在许多情况下,拥有快速的每CPU原子计数器是很有吸引力的:它不需要禁用中断来保护中
+断处理程序,它允许在NMI(Non Maskable Interrupt)处理程序中使用连贯的计数器。
+它对追踪目的和各种性能监测计数器特别有用。
+
+本地原子操作只保证在拥有数据的CPU上的变量修改的原子性。因此,必须注意确保只
+有一个CPU写到 ``local_t`` 的数据。这是通过使用每CPU的数据来实现的,并确
+保我们在一个抢占式安全上下文中修改它。然而,从任何一个CPU读取 ``local_t``
+数据都是允许的:这样它就会显得与所有者CPU的其他内存写入顺序不一致。
+
+
+针对特定架构的实现
+==================
+
+这可以通过稍微修改标准的原子操作来实现:只有它们的UP变体必须被保留。这通常
+意味着删除LOCK前缀(在i386和x86_64上)和任何SMP同步屏障。如果架构在SMP和
+UP之间没有不同的行为,在你的架构的 ``local.h`` 中包括 ``asm-generic/local.h``
+就足够了。
+
+通过在一个结构体中嵌入一个 ``atomic_long_t`` , ``local_t`` 类型被定义为
+一个不透明的 ``signed long`` 。这样做的目的是为了使从这个类型到
+``long`` 的转换失败。该定义看起来像::
+
+ typedef struct { atomic_long_t a; } local_t;
+
+
+使用本地原子操作时应遵循的规则
+==============================
+
+* 被本地操作触及的变量必须是每cpu的变量。
+
+* *只有* 这些变量的CPU所有者才可以写入这些变量。
+
+* 这个CPU可以从任何上下文(进程、中断、软中断、nmi...)中使用本地操作来更新
+ 它的local_t变量。
+
+* 当在进程上下文中使用本地操作时,必须禁用抢占(或中断),以确保进程在获得每
+ CPU变量和进行实际的本地操作之间不会被迁移到不同的CPU。
+
+* 当在中断上下文中使用本地操作时,在主线内核上不需要特别注意,因为它们将在局
+ 部CPU上运行,并且已经禁用了抢占。然而,我建议无论如何都要明确地禁用抢占,
+ 以确保它在-rt内核上仍能正确工作。
+
+* 读取本地cpu变量将提供该变量的当前拷贝。
+
+* 对这些变量的读取可以从任何CPU进行,因为对 “ ``long`` ”,对齐的变量的更新
+ 总是原子的。由于写入程序的CPU没有进行内存同步,所以在读取 *其他* cpu的变
+ 量时,可以读取该变量的过期副本。
+
+
+如何使用本地原子操作
+====================
+
+::
+
+ #include <linux/percpu.h>
+ #include <asm/local.h>
+
+ static DEFINE_PER_CPU(local_t, counters) = LOCAL_INIT(0);
+
+
+计数器
+======
+
+计数是在一个signed long的所有位上进行的。
+
+在可抢占的上下文中,围绕本地原子操作使用 ``get_cpu_var()`` 和
+``put_cpu_var()`` :它确保在对每个cpu变量进行写访问时,抢占被禁用。比如
+说::
+
+ local_inc(&get_cpu_var(counters));
+ put_cpu_var(counters);
+
+如果你已经在一个抢占安全上下文中,你可以使用 ``this_cpu_ptr()`` 代替::
+
+ local_inc(this_cpu_ptr(&counters));
+
+
+
+读取计数器
+==========
+
+那些本地计数器可以从外部的CPU中读取,以求得计数的总和。请注意,local_read
+所看到的跨CPU的数据必须被认为是相对于拥有该数据的CPU上发生的其他内存写入来
+说不符合顺序的::
+
+ long sum = 0;
+ for_each_online_cpu(cpu)
+ sum += local_read(&per_cpu(counters, cpu));
+
+如果你想使用远程local_read来同步CPU之间对资源的访问,必须在写入者和读取者
+的CPU上分别使用显式的 ``smp_wmb()`` 和 ``smp_rmb()`` 内存屏障。如果你使
+用 ``local_t`` 变量作为写在缓冲区中的字节的计数器,就会出现这种情况:在缓
+冲区写和计数器增量之间应该有一个 ``smp_wmb()`` ,在计数器读和缓冲区读之间
+也应有一个 ``smp_rmb()`` 。
+
+下面是一个使用 ``local.h`` 实现每个cpu基本计数器的示例模块::
+
+ /* test-local.c
+ *
+ * Sample module for local.h usage.
+ */
+
+
+ #include <asm/local.h>
+ #include <linux/module.h>
+ #include <linux/timer.h>
+
+ static DEFINE_PER_CPU(local_t, counters) = LOCAL_INIT(0);
+
+ static struct timer_list test_timer;
+
+ /* IPI called on each CPU. */
+ static void test_each(void *info)
+ {
+ /* Increment the counter from a non preemptible context */
+ printk("Increment on cpu %d\n", smp_processor_id());
+ local_inc(this_cpu_ptr(&counters));
+
+ /* This is what incrementing the variable would look like within a
+ * preemptible context (it disables preemption) :
+ *
+ * local_inc(&get_cpu_var(counters));
+ * put_cpu_var(counters);
+ */
+ }
+
+ static void do_test_timer(unsigned long data)
+ {
+ int cpu;
+
+ /* Increment the counters */
+ on_each_cpu(test_each, NULL, 1);
+ /* Read all the counters */
+ printk("Counters read from CPU %d\n", smp_processor_id());
+ for_each_online_cpu(cpu) {
+ printk("Read : CPU %d, count %ld\n", cpu,
+ local_read(&per_cpu(counters, cpu)));
+ }
+ mod_timer(&test_timer, jiffies + 1000);
+ }
+
+ static int __init test_init(void)
+ {
+ /* initialize the timer that will increment the counter */
+ timer_setup(&test_timer, do_test_timer, 0);
+ mod_timer(&test_timer, jiffies + 1);
+
+ return 0;
+ }
+
+ static void __exit test_exit(void)
+ {
+ timer_shutdown_sync(&test_timer);
+ }
+
+ module_init(test_init);
+ module_exit(test_exit);
+
+ MODULE_LICENSE("GPL");
+ MODULE_AUTHOR("Mathieu Desnoyers");
+ MODULE_DESCRIPTION("Local Atomic Ops");