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, 428 insertions, 0 deletions

diff --git a/lib/group_cpus.c b/lib/group_cpus.c
new file mode 100644
index 000000000..9c837a35f
--- /dev/null
+++ b/lib/group_cpus.c
@@ -0,0 +1,428 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2016 Thomas Gleixner.
+ * Copyright (C) 2016-2017 Christoph Hellwig.
+ */
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/cpu.h>
+#include <linux/sort.h>
+#include <linux/group_cpus.h>
+
+#ifdef CONFIG_SMP
+
+static void grp_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk,
+				unsigned int cpus_per_grp)
+{
+	const struct cpumask *siblmsk;
+	int cpu, sibl;
+
+	for ( ; cpus_per_grp > 0; ) {
+		cpu = cpumask_first(nmsk);
+
+		/* Should not happen, but I'm too lazy to think about it */
+		if (cpu >= nr_cpu_ids)
+			return;
+
+		cpumask_clear_cpu(cpu, nmsk);
+		cpumask_set_cpu(cpu, irqmsk);
+		cpus_per_grp--;
+
+		/* If the cpu has siblings, use them first */
+		siblmsk = topology_sibling_cpumask(cpu);
+		for (sibl = -1; cpus_per_grp > 0; ) {
+			sibl = cpumask_next(sibl, siblmsk);
+			if (sibl >= nr_cpu_ids)
+				break;
+			if (!cpumask_test_and_clear_cpu(sibl, nmsk))
+				continue;
+			cpumask_set_cpu(sibl, irqmsk);
+			cpus_per_grp--;
+		}
+	}
+}
+
+static cpumask_var_t *alloc_node_to_cpumask(void)
+{
+	cpumask_var_t *masks;
+	int node;
+
+	masks = kcalloc(nr_node_ids, sizeof(cpumask_var_t), GFP_KERNEL);
+	if (!masks)
+		return NULL;
+
+	for (node = 0; node < nr_node_ids; node++) {
+		if (!zalloc_cpumask_var(&masks[node], GFP_KERNEL))
+			goto out_unwind;
+	}
+
+	return masks;
+
+out_unwind:
+	while (--node >= 0)
+		free_cpumask_var(masks[node]);
+	kfree(masks);
+	return NULL;
+}
+
+static void free_node_to_cpumask(cpumask_var_t *masks)
+{
+	int node;
+
+	for (node = 0; node < nr_node_ids; node++)
+		free_cpumask_var(masks[node]);
+	kfree(masks);
+}
+
+static void build_node_to_cpumask(cpumask_var_t *masks)
+{
+	int cpu;
+
+	for_each_possible_cpu(cpu)
+		cpumask_set_cpu(cpu, masks[cpu_to_node(cpu)]);
+}
+
+static int get_nodes_in_cpumask(cpumask_var_t *node_to_cpumask,
+				const struct cpumask *mask, nodemask_t *nodemsk)
+{
+	int n, nodes = 0;
+
+	/* Calculate the number of nodes in the supplied affinity mask */
+	for_each_node(n) {
+		if (cpumask_intersects(mask, node_to_cpumask[n])) {
+			node_set(n, *nodemsk);
+			nodes++;
+		}
+	}
+	return nodes;
+}
+
+struct node_groups {
+	unsigned id;
+
+	union {
+		unsigned ngroups;
+		unsigned ncpus;
+	};
+};
+
+static int ncpus_cmp_func(const void *l, const void *r)
+{
+	const struct node_groups *ln = l;
+	const struct node_groups *rn = r;
+
+	return ln->ncpus - rn->ncpus;
+}
+
+/*
+ * Allocate group number for each node, so that for each node:
+ *
+ * 1) the allocated number is >= 1
+ *
+ * 2) the allocated number is <= active CPU number of this node
+ *
+ * The actual allocated total groups may be less than @numgrps when
+ * active total CPU number is less than @numgrps.
+ *
+ * Active CPUs means the CPUs in '@cpu_mask AND @node_to_cpumask[]'
+ * for each node.
+ */
+static void alloc_nodes_groups(unsigned int numgrps,
+			       cpumask_var_t *node_to_cpumask,
+			       const struct cpumask *cpu_mask,
+			       const nodemask_t nodemsk,
+			       struct cpumask *nmsk,
+			       struct node_groups *node_groups)
+{
+	unsigned n, remaining_ncpus = 0;
+
+	for (n = 0; n < nr_node_ids; n++) {
+		node_groups[n].id = n;
+		node_groups[n].ncpus = UINT_MAX;
+	}
+
+	for_each_node_mask(n, nodemsk) {
+		unsigned ncpus;
+
+		cpumask_and(nmsk, cpu_mask, node_to_cpumask[n]);
+		ncpus = cpumask_weight(nmsk);
+
+		if (!ncpus)
+			continue;
+		remaining_ncpus += ncpus;
+		node_groups[n].ncpus = ncpus;
+	}
+
+	numgrps = min_t(unsigned, remaining_ncpus, numgrps);
+
+	sort(node_groups, nr_node_ids, sizeof(node_groups[0]),
+	     ncpus_cmp_func, NULL);
+
+	/*
+	 * Allocate groups for each node according to the ratio of this
+	 * node's nr_cpus to remaining un-assigned ncpus. 'numgrps' is
+	 * bigger than number of active numa nodes. Always start the
+	 * allocation from the node with minimized nr_cpus.
+	 *
+	 * This way guarantees that each active node gets allocated at
+	 * least one group, and the theory is simple: over-allocation
+	 * is only done when this node is assigned by one group, so
+	 * other nodes will be allocated >= 1 groups, since 'numgrps' is
+	 * bigger than number of numa nodes.
+	 *
+	 * One perfect invariant is that number of allocated groups for
+	 * each node is <= CPU count of this node:
+	 *
+	 * 1) suppose there are two nodes: A and B
+	 * 	ncpu(X) is CPU count of node X
+	 * 	grps(X) is the group count allocated to node X via this
+	 * 	algorithm
+	 *
+	 * 	ncpu(A) <= ncpu(B)
+	 * 	ncpu(A) + ncpu(B) = N
+	 * 	grps(A) + grps(B) = G
+	 *
+	 * 	grps(A) = max(1, round_down(G * ncpu(A) / N))
+	 * 	grps(B) = G - grps(A)
+	 *
+	 * 	both N and G are integer, and 2 <= G <= N, suppose
+	 * 	G = N - delta, and 0 <= delta <= N - 2
+	 *
+	 * 2) obviously grps(A) <= ncpu(A) because:
+	 *
+	 * 	if grps(A) is 1, then grps(A) <= ncpu(A) given
+	 * 	ncpu(A) >= 1
+	 *
+	 * 	otherwise,
+	 * 		grps(A) <= G * ncpu(A) / N <= ncpu(A), given G <= N
+	 *
+	 * 3) prove how grps(B) <= ncpu(B):
+	 *
+	 * 	if round_down(G * ncpu(A) / N) == 0, vecs(B) won't be
+	 * 	over-allocated, so grps(B) <= ncpu(B),
+	 *
+	 * 	otherwise:
+	 *
+	 * 	grps(A) =
+	 * 		round_down(G * ncpu(A) / N) =
+	 * 		round_down((N - delta) * ncpu(A) / N) =
+	 * 		round_down((N * ncpu(A) - delta * ncpu(A)) / N)	 >=
+	 * 		round_down((N * ncpu(A) - delta * N) / N)	 =
+	 * 		cpu(A) - delta
+	 *
+	 * 	then:
+	 *
+	 * 	grps(A) - G >= ncpu(A) - delta - G
+	 * 	=>
+	 * 	G - grps(A) <= G + delta - ncpu(A)
+	 * 	=>
+	 * 	grps(B) <= N - ncpu(A)
+	 * 	=>
+	 * 	grps(B) <= cpu(B)
+	 *
+	 * For nodes >= 3, it can be thought as one node and another big
+	 * node given that is exactly what this algorithm is implemented,
+	 * and we always re-calculate 'remaining_ncpus' & 'numgrps', and
+	 * finally for each node X: grps(X) <= ncpu(X).
+	 *
+	 */
+	for (n = 0; n < nr_node_ids; n++) {
+		unsigned ngroups, ncpus;
+
+		if (node_groups[n].ncpus == UINT_MAX)
+			continue;
+
+		WARN_ON_ONCE(numgrps == 0);
+
+		ncpus = node_groups[n].ncpus;
+		ngroups = max_t(unsigned, 1,
+				 numgrps * ncpus / remaining_ncpus);
+		WARN_ON_ONCE(ngroups > ncpus);
+
+		node_groups[n].ngroups = ngroups;
+
+		remaining_ncpus -= ncpus;
+		numgrps -= ngroups;
+	}
+}
+
+static int __group_cpus_evenly(unsigned int startgrp, unsigned int numgrps,
+			       cpumask_var_t *node_to_cpumask,
+			       const struct cpumask *cpu_mask,
+			       struct cpumask *nmsk, struct cpumask *masks)
+{
+	unsigned int i, n, nodes, cpus_per_grp, extra_grps, done = 0;
+	unsigned int last_grp = numgrps;
+	unsigned int curgrp = startgrp;
+	nodemask_t nodemsk = NODE_MASK_NONE;
+	struct node_groups *node_groups;
+
+	if (cpumask_empty(cpu_mask))
+		return 0;
+
+	nodes = get_nodes_in_cpumask(node_to_cpumask, cpu_mask, &nodemsk);
+
+	/*
+	 * If the number of nodes in the mask is greater than or equal the
+	 * number of groups we just spread the groups across the nodes.
+	 */
+	if (numgrps <= nodes) {
+		for_each_node_mask(n, nodemsk) {
+			/* Ensure that only CPUs which are in both masks are set */
+			cpumask_and(nmsk, cpu_mask, node_to_cpumask[n]);
+			cpumask_or(&masks[curgrp], &masks[curgrp], nmsk);
+			if (++curgrp == last_grp)
+				curgrp = 0;
+		}
+		return numgrps;
+	}
+
+	node_groups = kcalloc(nr_node_ids,
+			       sizeof(struct node_groups),
+			       GFP_KERNEL);
+	if (!node_groups)
+		return -ENOMEM;
+
+	/* allocate group number for each node */
+	alloc_nodes_groups(numgrps, node_to_cpumask, cpu_mask,
+			   nodemsk, nmsk, node_groups);
+	for (i = 0; i < nr_node_ids; i++) {
+		unsigned int ncpus, v;
+		struct node_groups *nv = &node_groups[i];
+
+		if (nv->ngroups == UINT_MAX)
+			continue;
+
+		/* Get the cpus on this node which are in the mask */
+		cpumask_and(nmsk, cpu_mask, node_to_cpumask[nv->id]);
+		ncpus = cpumask_weight(nmsk);
+		if (!ncpus)
+			continue;
+
+		WARN_ON_ONCE(nv->ngroups > ncpus);
+
+		/* Account for rounding errors */
+		extra_grps = ncpus - nv->ngroups * (ncpus / nv->ngroups);
+
+		/* Spread allocated groups on CPUs of the current node */
+		for (v = 0; v < nv->ngroups; v++, curgrp++) {
+			cpus_per_grp = ncpus / nv->ngroups;
+
+			/* Account for extra groups to compensate rounding errors */
+			if (extra_grps) {
+				cpus_per_grp++;
+				--extra_grps;
+			}
+
+			/*
+			 * wrapping has to be considered given 'startgrp'
+			 * may start anywhere
+			 */
+			if (curgrp >= last_grp)
+				curgrp = 0;
+			grp_spread_init_one(&masks[curgrp], nmsk,
+						cpus_per_grp);
+		}
+		done += nv->ngroups;
+	}
+	kfree(node_groups);
+	return done;
+}
+
+/**
+ * group_cpus_evenly - Group all CPUs evenly per NUMA/CPU locality
+ * @numgrps: number of groups
+ *
+ * Return: cpumask array if successful, NULL otherwise. And each element
+ * includes CPUs assigned to this group
+ *
+ * Try to put close CPUs from viewpoint of CPU and NUMA locality into
+ * same group, and run two-stage grouping:
+ *	1) allocate present CPUs on these groups evenly first
+ *	2) allocate other possible CPUs on these groups evenly
+ *
+ * We guarantee in the resulted grouping that all CPUs are covered, and
+ * no same CPU is assigned to multiple groups
+ */
+struct cpumask *group_cpus_evenly(unsigned int numgrps)
+{
+	unsigned int curgrp = 0, nr_present = 0, nr_others = 0;
+	cpumask_var_t *node_to_cpumask;
+	cpumask_var_t nmsk, npresmsk;
+	int ret = -ENOMEM;
+	struct cpumask *masks = NULL;
+
+	if (!zalloc_cpumask_var(&nmsk, GFP_KERNEL))
+		return NULL;
+
+	if (!zalloc_cpumask_var(&npresmsk, GFP_KERNEL))
+		goto fail_nmsk;
+
+	node_to_cpumask = alloc_node_to_cpumask();
+	if (!node_to_cpumask)
+		goto fail_npresmsk;
+
+	masks = kcalloc(numgrps, sizeof(*masks), GFP_KERNEL);
+	if (!masks)
+		goto fail_node_to_cpumask;
+
+	/* Stabilize the cpumasks */
+	cpus_read_lock();
+	build_node_to_cpumask(node_to_cpumask);
+
+	/* grouping present CPUs first */
+	ret = __group_cpus_evenly(curgrp, numgrps, node_to_cpumask,
+				  cpu_present_mask, nmsk, masks);
+	if (ret < 0)
+		goto fail_build_affinity;
+	nr_present = ret;
+
+	/*
+	 * Allocate non present CPUs starting from the next group to be
+	 * handled. If the grouping of present CPUs already exhausted the
+	 * group space, assign the non present CPUs to the already
+	 * allocated out groups.
+	 */
+	if (nr_present >= numgrps)
+		curgrp = 0;
+	else
+		curgrp = nr_present;
+	cpumask_andnot(npresmsk, cpu_possible_mask, cpu_present_mask);
+	ret = __group_cpus_evenly(curgrp, numgrps, node_to_cpumask,
+				  npresmsk, nmsk, masks);
+	if (ret >= 0)
+		nr_others = ret;
+
+ fail_build_affinity:
+	cpus_read_unlock();
+
+	if (ret >= 0)
+		WARN_ON(nr_present + nr_others < numgrps);
+
+ fail_node_to_cpumask:
+	free_node_to_cpumask(node_to_cpumask);
+
+ fail_npresmsk:
+	free_cpumask_var(npresmsk);
+
+ fail_nmsk:
+	free_cpumask_var(nmsk);
+	if (ret < 0) {
+		kfree(masks);
+		return NULL;
+	}
+	return masks;
+}
+#else /* CONFIG_SMP */
+struct cpumask *group_cpus_evenly(unsigned int numgrps)
+{
+	struct cpumask *masks = kcalloc(numgrps, sizeof(*masks), GFP_KERNEL);
+
+	if (!masks)
+		return NULL;
+
+	/* assign all CPUs(cpu 0) to the 1st group only */
+	cpumask_copy(&masks[0], cpu_possible_mask);
+	return masks;
+}
+#endif /* CONFIG_SMP */