scx: Add "maximal" scheduler testcase

We recently added a "minimal" scheduler testcase that loaded the bare
minimum of fields to exercise the default codepaths for ext.c. Let's add
a "maximal" testcase which defines every single defined sched_ext_ops
callback and verifies that it's successfully able to be loaded.

Signed-off-by: David Vernet <void@manifault.com>

tools/testing/selftests/scx/.gitignore

@@ -3,6 +3,7 @@ ddsp_vtimelocal_fail
 enq_last_no_enq_fails
 enq_select_cpu_fails
 init_enable_count
+maximal
 minimal
 runner
 select_cpu_dfl

tools/testing/selftests/scx/Makefile

@@ -162,6 +162,7 @@ auto-test-targets :=			\
 	ddsp_vtimelocal_fail		\
 	init_enable_count		\
 	maybe_null			\
+	maximal				\
 	minimal				\
 	select_cpu_dfl			\
 	select_cpu_dfl_nodispatch	\

tools/testing/selftests/scx/maximal.bpf.c

@@ -0,0 +1,165 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * A scheduler with every callback defined.
+ *
+ * This scheduler defines every callback.
+ *
+ * Copyright (c) 2024 Meta Platforms, Inc. and affiliates.
+ * Copyright (c) 2024 David Vernet <dvernet@meta.com>
+ * Copyright (c) 2024 Tejun Heo <tj@kernel.org>
+ */
+
+#include <scx/common.bpf.h>
+
+char _license[] SEC("license") = "GPL";
+
+s32 BPF_STRUCT_OPS(maximal_select_cpu, struct task_struct *p, s32 prev_cpu,
+		   u64 wake_flags)
+{
+	return prev_cpu;
+}
+
+void BPF_STRUCT_OPS(maximal_enqueue, struct task_struct *p, u64 enq_flags)
+{
+	scx_bpf_dispatch(p, SCX_DSQ_GLOBAL, SCX_SLICE_DFL, enq_flags);
+}
+
+void BPF_STRUCT_OPS(maximal_dequeue, struct task_struct *p, u64 deq_flags)
+{}
+
+void BPF_STRUCT_OPS(maximal_dispatch, s32 cpu, struct task_struct *prev)
+{
+	scx_bpf_consume(SCX_DSQ_GLOBAL);
+}
+
+void BPF_STRUCT_OPS(maximal_runnable, struct task_struct *p, u64 enq_flags)
+{}
+
+void BPF_STRUCT_OPS(maximal_running, struct task_struct *p)
+{}
+
+void BPF_STRUCT_OPS(maximal_stopping, struct task_struct *p, bool runnable)
+{}
+
+void BPF_STRUCT_OPS(maximal_quiescent, struct task_struct *p, u64 deq_flags)
+{}
+
+bool BPF_STRUCT_OPS(maximal_yield, struct task_struct *from,
+		    struct task_struct *to)
+{
+	return false;
+}
+
+bool BPF_STRUCT_OPS(maximal_core_sched_before, struct task_struct *a,
+		    struct task_struct *b)
+{
+	return false;
+}
+
+void BPF_STRUCT_OPS(maximal_set_weight, struct task_struct *p, u32 weight)
+{}
+
+void BPF_STRUCT_OPS(maximal_set_cpumask, struct task_struct *p,
+		    const struct cpumask *cpumask)
+{}
+
+void BPF_STRUCT_OPS(maximal_update_idle, s32 cpu, bool idle)
+{}
+
+void BPF_STRUCT_OPS(maximal_cpu_acquire, s32 cpu,
+		    struct scx_cpu_acquire_args *args)
+{}
+
+void BPF_STRUCT_OPS(maximal_cpu_release, s32 cpu,
+		    struct scx_cpu_release_args *args)
+{}
+
+void BPF_STRUCT_OPS(maximal_cpu_online, s32 cpu)
+{}
+
+void BPF_STRUCT_OPS(maximal_cpu_offline, s32 cpu)
+{}
+
+s32 BPF_STRUCT_OPS(maximal_init_task, struct task_struct *p,
+		   struct scx_init_task_args *args)
+{
+	return 0;
+}
+
+void BPF_STRUCT_OPS(maximal_enable, struct task_struct *p)
+{}
+
+void BPF_STRUCT_OPS(maximal_exit_task, struct task_struct *p,
+		    struct scx_exit_task_args *args)
+{}
+
+void BPF_STRUCT_OPS(maximal_disable, struct task_struct *p)
+{}
+
+s32 BPF_STRUCT_OPS(maximal_cgroup_init, struct cgroup *cgrp,
+		   struct scx_cgroup_init_args *args)
+{
+	return 0;
+}
+
+void BPF_STRUCT_OPS(maximal_cgroup_exit, struct cgroup *cgrp)
+{}
+
+s32 BPF_STRUCT_OPS(maximal_cgroup_prep_move, struct task_struct *p,
+		   struct cgroup *from, struct cgroup *to)
+{
+	return 0;
+}
+
+void BPF_STRUCT_OPS(maximal_cgroup_move, struct task_struct *p,
+		    struct cgroup *from, struct cgroup *to)
+{}
+
+void BPF_STRUCT_OPS(maximal_cgroup_cancel_move, struct task_struct *p,
+	       struct cgroup *from, struct cgroup *to)
+{}
+
+void BPF_STRUCT_OPS(maximal_cgroup_set_weight, struct cgroup *cgrp, u32 weight)
+{}
+
+s32 BPF_STRUCT_OPS_SLEEPABLE(maximal_init)
+{
+	return 0;
+}
+
+void BPF_STRUCT_OPS(maximal_exit, struct scx_exit_info *info)
+{}
+
+SEC(".struct_ops.link")
+struct sched_ext_ops maximal_ops = {
+	.select_cpu		= maximal_select_cpu,
+	.enqueue		= maximal_enqueue,
+	.dequeue		= maximal_dequeue,
+	.dispatch		= maximal_dispatch,
+	.runnable		= maximal_runnable,
+	.running		= maximal_running,
+	.stopping		= maximal_stopping,
+	.quiescent		= maximal_quiescent,
+	.yield			= maximal_yield,
+	.core_sched_before	= maximal_core_sched_before,
+	.set_weight		= maximal_set_weight,
+	.set_cpumask		= maximal_set_cpumask,
+	.update_idle		= maximal_update_idle,
+	.cpu_acquire		= maximal_cpu_acquire,
+	.cpu_release		= maximal_cpu_release,
+	.cpu_online		= maximal_cpu_online,
+	.cpu_offline		= maximal_cpu_offline,
+	.init_task		= maximal_init_task,
+	.enable			= maximal_enable,
+	.exit_task		= maximal_exit_task,
+	.disable		= maximal_disable,
+	.cgroup_init		= maximal_cgroup_init,
+	.cgroup_exit		= maximal_cgroup_exit,
+	.cgroup_prep_move	= maximal_cgroup_prep_move,
+	.cgroup_move		= maximal_cgroup_move,
+	.cgroup_cancel_move	= maximal_cgroup_cancel_move,
+	.cgroup_set_weight	= maximal_cgroup_set_weight,
+	.init			= maximal_init,
+	.exit			= maximal_exit,
+	.name			= "maximal",
+};

tools/testing/selftests/scx/maximal.c

@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2024 Meta Platforms, Inc. and affiliates.
+ * Copyright (c) 2024 David Vernet <dvernet@meta.com>
+ * Copyright (c) 2024 Tejun Heo <tj@kernel.org>
+ */
+#include <bpf/bpf.h>
+#include <scx/common.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include "maximal.bpf.skel.h"
+#include "scx_test.h"
+
+static enum scx_test_status setup(void **ctx)
+{
+	struct maximal *skel;
+
+	skel = maximal__open_and_load();
+	SCX_FAIL_IF(!skel, "Failed to open and load skel");
+	*ctx = skel;
+
+	return SCX_TEST_PASS;
+}
+
+static enum scx_test_status run(void *ctx)
+{
+	struct maximal *skel = ctx;
+	struct bpf_link *link;
+
+	link = bpf_map__attach_struct_ops(skel->maps.maximal_ops);
+	SCX_FAIL_IF(!link, "Failed to attach scheduler");
+
+	bpf_link__destroy(link);
+
+	return SCX_TEST_PASS;
+}
+
+static void cleanup(void *ctx)
+{
+	struct maximal *skel = ctx;
+
+	maximal__destroy(skel);
+}
+
+struct scx_test maximal = {
+	.name = "maximal",
+	.description = "Verify we can load a scheduler with every callback defined",
+	.setup = setup,
+	.run = run,
+	.cleanup = cleanup,
+};
+REGISTER_SCX_TEST(&maximal)