1/* SPDX-License-Identifier: GPL-2.0 */
 2/*
 3 * Copyright (c) 2023 Meta Platforms, Inc. and affiliates.
 4 * Copyright (c) 2023 David Vernet <dvernet@meta.com>
 5 * Copyright (c) 2023 Tejun Heo <tj@kernel.org>
 6 */
 7
 8#include <scx/common.bpf.h>
 9
10char _license[] SEC("license") = "GPL";
11
12/* Manually specify the signature until the kfunc is added to the scx repo. */
13s32 scx_bpf_select_cpu_dfl(struct task_struct *p, s32 prev_cpu, u64 wake_flags,
14			   bool *found) __ksym;
15
16s32 BPF_STRUCT_OPS(enq_select_cpu_fails_select_cpu, struct task_struct *p,
17		   s32 prev_cpu, u64 wake_flags)
18{
19	return prev_cpu;
20}
21
22void BPF_STRUCT_OPS(enq_select_cpu_fails_enqueue, struct task_struct *p,
23		    u64 enq_flags)
24{
25	/*
26	 * Need to initialize the variable or the verifier will fail to load.
27	 * Improving these semantics is actively being worked on.
28	 */
29	bool found = false;
30
31	/* Can only call from ops.select_cpu() */
32	scx_bpf_select_cpu_dfl(p, 0, 0, &found);
33
34	scx_bpf_dsq_insert(p, SCX_DSQ_GLOBAL, SCX_SLICE_DFL, enq_flags);
35}
36
37SEC(".struct_ops.link")
38struct sched_ext_ops enq_select_cpu_fails_ops = {
39	.select_cpu		= (void *) enq_select_cpu_fails_select_cpu,
40	.enqueue		= (void *) enq_select_cpu_fails_enqueue,
41	.name			= "enq_select_cpu_fails",
42	.timeout_ms		= 1000U,
43};