SCX eBPF macro BPF_STRUCT_OPS

v6.12

The BPF_STRUCT_OPS macro makes it easier to define sleepable struct ops programs correctly.

Definition

#define BPF_STRUCT_OPS_SLEEPABLE(name, args...)   \
    SEC("struct_ops.s/"#name)             \
    BPF_PROG(name, ##args)

Usage

This macro can be used to shorted the definition of a sleepable struct ops programs. It places the program in an ELF section starting with struct_ops.s/ and names the program with the given name, this signals the loader of the program type. It also unpacks the program context into the arguments specified via args. See BPF_PROG for details.

Example

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright (c) 2024 Meta Platforms, Inc. and affiliates.
 * Copyright (c) 2024 David Vernet <dvernet@meta.com>
 */

static void exit_from_hotplug(s32 cpu, bool onlining)
{
    /*
     * Ignored, just used to verify that we can invoke blocking kfuncs
     * from the hotplug path.
     */
    scx_bpf_create_dsq(0, -1);

    s64 code = SCX_ECODE_ACT_RESTART | HOTPLUG_EXIT_RSN;

    if (onlining)
        code |= HOTPLUG_ONLINING;

    scx_bpf_exit(code, "hotplug event detected (%d going %s)", cpu,
             onlining ? "online" : "offline");
}

void BPF_STRUCT_OPS_SLEEPABLE(hotplug_cpu_online, s32 cpu)
{
    exit_from_hotplug(cpu, true);
}