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, 439 insertions, 0 deletions

diff --git a/arch/sparc/kernel/cpumap.c b/arch/sparc/kernel/cpumap.c
new file mode 100644
index 000000000..f07ea88a8
--- /dev/null
+++ b/arch/sparc/kernel/cpumap.c
@@ -0,0 +1,439 @@
+// SPDX-License-Identifier: GPL-2.0
+/* cpumap.c: used for optimizing CPU assignment
+ *
+ * Copyright (C) 2009 Hong H. Pham <hong.pham@windriver.com>
+ */
+
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/cpumask.h>
+#include <linux/spinlock.h>
+#include <asm/cpudata.h>
+#include "cpumap.h"
+
+
+enum {
+	CPUINFO_LVL_ROOT = 0,
+	CPUINFO_LVL_NODE,
+	CPUINFO_LVL_CORE,
+	CPUINFO_LVL_PROC,
+	CPUINFO_LVL_MAX,
+};
+
+enum {
+	ROVER_NO_OP              = 0,
+	/* Increment rover every time level is visited */
+	ROVER_INC_ON_VISIT       = 1 << 0,
+	/* Increment parent's rover every time rover wraps around */
+	ROVER_INC_PARENT_ON_LOOP = 1 << 1,
+};
+
+struct cpuinfo_node {
+	int id;
+	int level;
+	int num_cpus;    /* Number of CPUs in this hierarchy */
+	int parent_index;
+	int child_start; /* Array index of the first child node */
+	int child_end;   /* Array index of the last child node */
+	int rover;       /* Child node iterator */
+};
+
+struct cpuinfo_level {
+	int start_index; /* Index of first node of a level in a cpuinfo tree */
+	int end_index;   /* Index of last node of a level in a cpuinfo tree */
+	int num_nodes;   /* Number of nodes in a level in a cpuinfo tree */
+};
+
+struct cpuinfo_tree {
+	int total_nodes;
+
+	/* Offsets into nodes[] for each level of the tree */
+	struct cpuinfo_level level[CPUINFO_LVL_MAX];
+	struct cpuinfo_node  nodes[];
+};
+
+
+static struct cpuinfo_tree *cpuinfo_tree;
+
+static u16 cpu_distribution_map[NR_CPUS];
+static DEFINE_SPINLOCK(cpu_map_lock);
+
+
+/* Niagara optimized cpuinfo tree traversal. */
+static const int niagara_iterate_method[] = {
+	[CPUINFO_LVL_ROOT] = ROVER_NO_OP,
+
+	/* Strands (or virtual CPUs) within a core may not run concurrently
+	 * on the Niagara, as instruction pipeline(s) are shared.  Distribute
+	 * work to strands in different cores first for better concurrency.
+	 * Go to next NUMA node when all cores are used.
+	 */
+	[CPUINFO_LVL_NODE] = ROVER_INC_ON_VISIT|ROVER_INC_PARENT_ON_LOOP,
+
+	/* Strands are grouped together by proc_id in cpuinfo_sparc, i.e.
+	 * a proc_id represents an instruction pipeline.  Distribute work to
+	 * strands in different proc_id groups if the core has multiple
+	 * instruction pipelines (e.g. the Niagara 2/2+ has two).
+	 */
+	[CPUINFO_LVL_CORE] = ROVER_INC_ON_VISIT,
+
+	/* Pick the next strand in the proc_id group. */
+	[CPUINFO_LVL_PROC] = ROVER_INC_ON_VISIT,
+};
+
+/* Generic cpuinfo tree traversal.  Distribute work round robin across NUMA
+ * nodes.
+ */
+static const int generic_iterate_method[] = {
+	[CPUINFO_LVL_ROOT] = ROVER_INC_ON_VISIT,
+	[CPUINFO_LVL_NODE] = ROVER_NO_OP,
+	[CPUINFO_LVL_CORE] = ROVER_INC_PARENT_ON_LOOP,
+	[CPUINFO_LVL_PROC] = ROVER_INC_ON_VISIT|ROVER_INC_PARENT_ON_LOOP,
+};
+
+
+static int cpuinfo_id(int cpu, int level)
+{
+	int id;
+
+	switch (level) {
+	case CPUINFO_LVL_ROOT:
+		id = 0;
+		break;
+	case CPUINFO_LVL_NODE:
+		id = cpu_to_node(cpu);
+		break;
+	case CPUINFO_LVL_CORE:
+		id = cpu_data(cpu).core_id;
+		break;
+	case CPUINFO_LVL_PROC:
+		id = cpu_data(cpu).proc_id;
+		break;
+	default:
+		id = -EINVAL;
+	}
+	return id;
+}
+
+/*
+ * Enumerate the CPU information in __cpu_data to determine the start index,
+ * end index, and number of nodes for each level in the cpuinfo tree.  The
+ * total number of cpuinfo nodes required to build the tree is returned.
+ */
+static int enumerate_cpuinfo_nodes(struct cpuinfo_level *tree_level)
+{
+	int prev_id[CPUINFO_LVL_MAX];
+	int i, n, num_nodes;
+
+	for (i = CPUINFO_LVL_ROOT; i < CPUINFO_LVL_MAX; i++) {
+		struct cpuinfo_level *lv = &tree_level[i];
+
+		prev_id[i] = -1;
+		lv->start_index = lv->end_index = lv->num_nodes = 0;
+	}
+
+	num_nodes = 1; /* Include the root node */
+
+	for (i = 0; i < num_possible_cpus(); i++) {
+		if (!cpu_online(i))
+			continue;
+
+		n = cpuinfo_id(i, CPUINFO_LVL_NODE);
+		if (n > prev_id[CPUINFO_LVL_NODE]) {
+			tree_level[CPUINFO_LVL_NODE].num_nodes++;
+			prev_id[CPUINFO_LVL_NODE] = n;
+			num_nodes++;
+		}
+		n = cpuinfo_id(i, CPUINFO_LVL_CORE);
+		if (n > prev_id[CPUINFO_LVL_CORE]) {
+			tree_level[CPUINFO_LVL_CORE].num_nodes++;
+			prev_id[CPUINFO_LVL_CORE] = n;
+			num_nodes++;
+		}
+		n = cpuinfo_id(i, CPUINFO_LVL_PROC);
+		if (n > prev_id[CPUINFO_LVL_PROC]) {
+			tree_level[CPUINFO_LVL_PROC].num_nodes++;
+			prev_id[CPUINFO_LVL_PROC] = n;
+			num_nodes++;
+		}
+	}
+
+	tree_level[CPUINFO_LVL_ROOT].num_nodes = 1;
+
+	n = tree_level[CPUINFO_LVL_NODE].num_nodes;
+	tree_level[CPUINFO_LVL_NODE].start_index = 1;
+	tree_level[CPUINFO_LVL_NODE].end_index   = n;
+
+	n++;
+	tree_level[CPUINFO_LVL_CORE].start_index = n;
+	n += tree_level[CPUINFO_LVL_CORE].num_nodes;
+	tree_level[CPUINFO_LVL_CORE].end_index   = n - 1;
+
+	tree_level[CPUINFO_LVL_PROC].start_index = n;
+	n += tree_level[CPUINFO_LVL_PROC].num_nodes;
+	tree_level[CPUINFO_LVL_PROC].end_index   = n - 1;
+
+	return num_nodes;
+}
+
+/* Build a tree representation of the CPU hierarchy using the per CPU
+ * information in __cpu_data.  Entries in __cpu_data[0..NR_CPUS] are
+ * assumed to be sorted in ascending order based on node, core_id, and
+ * proc_id (in order of significance).
+ */
+static struct cpuinfo_tree *build_cpuinfo_tree(void)
+{
+	struct cpuinfo_tree *new_tree;
+	struct cpuinfo_node *node;
+	struct cpuinfo_level tmp_level[CPUINFO_LVL_MAX];
+	int num_cpus[CPUINFO_LVL_MAX];
+	int level_rover[CPUINFO_LVL_MAX];
+	int prev_id[CPUINFO_LVL_MAX];
+	int n, id, cpu, prev_cpu, last_cpu, level;
+
+	n = enumerate_cpuinfo_nodes(tmp_level);
+
+	new_tree = kzalloc(struct_size(new_tree, nodes, n), GFP_ATOMIC);
+	if (!new_tree)
+		return NULL;
+
+	new_tree->total_nodes = n;
+	memcpy(&new_tree->level, tmp_level, sizeof(tmp_level));
+
+	prev_cpu = cpu = cpumask_first(cpu_online_mask);
+
+	/* Initialize all levels in the tree with the first CPU */
+	for (level = CPUINFO_LVL_PROC; level >= CPUINFO_LVL_ROOT; level--) {
+		n = new_tree->level[level].start_index;
+
+		level_rover[level] = n;
+		node = &new_tree->nodes[n];
+
+		id = cpuinfo_id(cpu, level);
+		if (unlikely(id < 0)) {
+			kfree(new_tree);
+			return NULL;
+		}
+		node->id = id;
+		node->level = level;
+		node->num_cpus = 1;
+
+		node->parent_index = (level > CPUINFO_LVL_ROOT)
+		    ? new_tree->level[level - 1].start_index : -1;
+
+		node->child_start = node->child_end = node->rover =
+		    (level == CPUINFO_LVL_PROC)
+		    ? cpu : new_tree->level[level + 1].start_index;
+
+		prev_id[level] = node->id;
+		num_cpus[level] = 1;
+	}
+
+	for (last_cpu = (num_possible_cpus() - 1); last_cpu >= 0; last_cpu--) {
+		if (cpu_online(last_cpu))
+			break;
+	}
+
+	while (++cpu <= last_cpu) {
+		if (!cpu_online(cpu))
+			continue;
+
+		for (level = CPUINFO_LVL_PROC; level >= CPUINFO_LVL_ROOT;
+		     level--) {
+			id = cpuinfo_id(cpu, level);
+			if (unlikely(id < 0)) {
+				kfree(new_tree);
+				return NULL;
+			}
+
+			if ((id != prev_id[level]) || (cpu == last_cpu)) {
+				prev_id[level] = id;
+				node = &new_tree->nodes[level_rover[level]];
+				node->num_cpus = num_cpus[level];
+				num_cpus[level] = 1;
+
+				if (cpu == last_cpu)
+					node->num_cpus++;
+
+				/* Connect tree node to parent */
+				if (level == CPUINFO_LVL_ROOT)
+					node->parent_index = -1;
+				else
+					node->parent_index =
+					    level_rover[level - 1];
+
+				if (level == CPUINFO_LVL_PROC) {
+					node->child_end =
+					    (cpu == last_cpu) ? cpu : prev_cpu;
+				} else {
+					node->child_end =
+					    level_rover[level + 1] - 1;
+				}
+
+				/* Initialize the next node in the same level */
+				n = ++level_rover[level];
+				if (n <= new_tree->level[level].end_index) {
+					node = &new_tree->nodes[n];
+					node->id = id;
+					node->level = level;
+
+					/* Connect node to child */
+					node->child_start = node->child_end =
+					node->rover =
+					    (level == CPUINFO_LVL_PROC)
+					    ? cpu : level_rover[level + 1];
+				}
+			} else
+				num_cpus[level]++;
+		}
+		prev_cpu = cpu;
+	}
+
+	return new_tree;
+}
+
+static void increment_rover(struct cpuinfo_tree *t, int node_index,
+                            int root_index, const int *rover_inc_table)
+{
+	struct cpuinfo_node *node = &t->nodes[node_index];
+	int top_level, level;
+
+	top_level = t->nodes[root_index].level;
+	for (level = node->level; level >= top_level; level--) {
+		node->rover++;
+		if (node->rover <= node->child_end)
+			return;
+
+		node->rover = node->child_start;
+		/* If parent's rover does not need to be adjusted, stop here. */
+		if ((level == top_level) ||
+		    !(rover_inc_table[level] & ROVER_INC_PARENT_ON_LOOP))
+			return;
+
+		node = &t->nodes[node->parent_index];
+	}
+}
+
+static int iterate_cpu(struct cpuinfo_tree *t, unsigned int root_index)
+{
+	const int *rover_inc_table;
+	int level, new_index, index = root_index;
+
+	switch (sun4v_chip_type) {
+	case SUN4V_CHIP_NIAGARA1:
+	case SUN4V_CHIP_NIAGARA2:
+	case SUN4V_CHIP_NIAGARA3:
+	case SUN4V_CHIP_NIAGARA4:
+	case SUN4V_CHIP_NIAGARA5:
+	case SUN4V_CHIP_SPARC_M6:
+	case SUN4V_CHIP_SPARC_M7:
+	case SUN4V_CHIP_SPARC_M8:
+	case SUN4V_CHIP_SPARC_SN:
+	case SUN4V_CHIP_SPARC64X:
+		rover_inc_table = niagara_iterate_method;
+		break;
+	default:
+		rover_inc_table = generic_iterate_method;
+	}
+
+	for (level = t->nodes[root_index].level; level < CPUINFO_LVL_MAX;
+	     level++) {
+		new_index = t->nodes[index].rover;
+		if (rover_inc_table[level] & ROVER_INC_ON_VISIT)
+			increment_rover(t, index, root_index, rover_inc_table);
+
+		index = new_index;
+	}
+	return index;
+}
+
+static void _cpu_map_rebuild(void)
+{
+	int i;
+
+	if (cpuinfo_tree) {
+		kfree(cpuinfo_tree);
+		cpuinfo_tree = NULL;
+	}
+
+	cpuinfo_tree = build_cpuinfo_tree();
+	if (!cpuinfo_tree)
+		return;
+
+	/* Build CPU distribution map that spans all online CPUs.  No need
+	 * to check if the CPU is online, as that is done when the cpuinfo
+	 * tree is being built.
+	 */
+	for (i = 0; i < cpuinfo_tree->nodes[0].num_cpus; i++)
+		cpu_distribution_map[i] = iterate_cpu(cpuinfo_tree, 0);
+}
+
+/* Fallback if the cpuinfo tree could not be built.  CPU mapping is linear
+ * round robin.
+ */
+static int simple_map_to_cpu(unsigned int index)
+{
+	int i, end, cpu_rover;
+
+	cpu_rover = 0;
+	end = index % num_online_cpus();
+	for (i = 0; i < num_possible_cpus(); i++) {
+		if (cpu_online(cpu_rover)) {
+			if (cpu_rover >= end)
+				return cpu_rover;
+
+			cpu_rover++;
+		}
+	}
+
+	/* Impossible, since num_online_cpus() <= num_possible_cpus() */
+	return cpumask_first(cpu_online_mask);
+}
+
+static int _map_to_cpu(unsigned int index)
+{
+	struct cpuinfo_node *root_node;
+
+	if (unlikely(!cpuinfo_tree)) {
+		_cpu_map_rebuild();
+		if (!cpuinfo_tree)
+			return simple_map_to_cpu(index);
+	}
+
+	root_node = &cpuinfo_tree->nodes[0];
+#ifdef CONFIG_HOTPLUG_CPU
+	if (unlikely(root_node->num_cpus != num_online_cpus())) {
+		_cpu_map_rebuild();
+		if (!cpuinfo_tree)
+			return simple_map_to_cpu(index);
+	}
+#endif
+	return cpu_distribution_map[index % root_node->num_cpus];
+}
+
+int map_to_cpu(unsigned int index)
+{
+	int mapped_cpu;
+	unsigned long flag;
+
+	spin_lock_irqsave(&cpu_map_lock, flag);
+	mapped_cpu = _map_to_cpu(index);
+
+#ifdef CONFIG_HOTPLUG_CPU
+	while (unlikely(!cpu_online(mapped_cpu)))
+		mapped_cpu = _map_to_cpu(index);
+#endif
+	spin_unlock_irqrestore(&cpu_map_lock, flag);
+	return mapped_cpu;
+}
+EXPORT_SYMBOL(map_to_cpu);
+
+void cpu_map_rebuild(void)
+{
+	unsigned long flag;
+
+	spin_lock_irqsave(&cpu_map_lock, flag);
+	_cpu_map_rebuild();
+	spin_unlock_irqrestore(&cpu_map_lock, flag);
+}