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1/* SPDX-License-Identifier: GPL-2.0 */2/*3 * A scheduler that validates the behavior of direct dispatching with a default4 * select_cpu implementation, and with the SCX_OPS_ENQ_DFL_NO_DISPATCH ops flag5 * specified.6 *7 * Copyright (c) 2023 Meta Platforms, Inc. and affiliates.8 * Copyright (c) 2023 David Vernet <dvernet@meta.com>9 * Copyright (c) 2023 Tejun Heo <tj@kernel.org>10 */11 12#include <scx/common.bpf.h>13 14char _license[] SEC("license") = "GPL";15 16bool saw_local = false;17 18/* Per-task scheduling context */19struct task_ctx {20 bool force_local; /* CPU changed by ops.select_cpu() */21};22 23struct {24 __uint(type, BPF_MAP_TYPE_TASK_STORAGE);25 __uint(map_flags, BPF_F_NO_PREALLOC);26 __type(key, int);27 __type(value, struct task_ctx);28} task_ctx_stor SEC(".maps");29 30/* Manually specify the signature until the kfunc is added to the scx repo. */31s32 scx_bpf_select_cpu_dfl(struct task_struct *p, s32 prev_cpu, u64 wake_flags,32 bool *found) __ksym;33 34s32 BPF_STRUCT_OPS(select_cpu_dfl_nodispatch_select_cpu, struct task_struct *p,35 s32 prev_cpu, u64 wake_flags)36{37 struct task_ctx *tctx;38 s32 cpu;39 40 tctx = bpf_task_storage_get(&task_ctx_stor, p, 0, 0);41 if (!tctx) {42 scx_bpf_error("task_ctx lookup failed");43 return -ESRCH;44 }45 46 cpu = scx_bpf_select_cpu_dfl(p, prev_cpu, wake_flags,47 &tctx->force_local);48 49 return cpu;50}51 52void BPF_STRUCT_OPS(select_cpu_dfl_nodispatch_enqueue, struct task_struct *p,53 u64 enq_flags)54{55 u64 dsq_id = SCX_DSQ_GLOBAL;56 struct task_ctx *tctx;57 58 tctx = bpf_task_storage_get(&task_ctx_stor, p, 0, 0);59 if (!tctx) {60 scx_bpf_error("task_ctx lookup failed");61 return;62 }63 64 if (tctx->force_local) {65 dsq_id = SCX_DSQ_LOCAL;66 tctx->force_local = false;67 saw_local = true;68 }69 70 scx_bpf_dispatch(p, dsq_id, SCX_SLICE_DFL, enq_flags);71}72 73s32 BPF_STRUCT_OPS(select_cpu_dfl_nodispatch_init_task,74 struct task_struct *p, struct scx_init_task_args *args)75{76 if (bpf_task_storage_get(&task_ctx_stor, p, 0,77 BPF_LOCAL_STORAGE_GET_F_CREATE))78 return 0;79 else80 return -ENOMEM;81}82 83SEC(".struct_ops.link")84struct sched_ext_ops select_cpu_dfl_nodispatch_ops = {85 .select_cpu = (void *) select_cpu_dfl_nodispatch_select_cpu,86 .enqueue = (void *) select_cpu_dfl_nodispatch_enqueue,87 .init_task = (void *) select_cpu_dfl_nodispatch_init_task,88 .name = "select_cpu_dfl_nodispatch",89};90