From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B72A82ED141; Sat, 19 Sep 2026 00:28:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789777723; cv=none; b=J8skQHUEdUZCc62zcnYAPY/prqcRFMH0A1zBUz6czU1iWux91XmEmQScADSb7zpHQAVckvmjny6/x3XB8P78QjRrIMTQCHklbK/CCul/6z6NRQYiIzDJHX2zZyCO5NNcAJ3p5uYCKvmTvQ0bZSW838y+SO3Q4CKhTmZbuVozmWA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789777723; c=relaxed/simple; bh=+H3cdbhKxz1J/rZHSWd3dY30FqYrKjPUcIW5SY27YwQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cbUJqX9p4+qDtdtpwTLn7bXsik8C9fHFhQAr/rNlDkJBmlQIHDZQdw3i5JRGOZMrQVNhZjLpw56tIi3gov6gse0EcfPkKIhNvorQNNAaNjkR/PRmVnL7anu/gbR0lvCiFlI2HgCd1FskikOZrJyixZGD7iUSedTMw9XbtlOsCB4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=feRwfKfe; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="feRwfKfe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3D28B1F000FF; Sat, 19 Sep 2026 00:28:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789777721; bh=dfg0s8xs53MvcxnXE1uoQVYF8m16Kf6WCw2fJIoPmQE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=feRwfKfeeesaUSGVdDOXw2mqgG62n33mjAmFw5Z1leXVd38lPvmR7MclP3NVFwxDV nQK+hvAPbHzNSau0lbFvuUe+yVZT9Z8xOxG+BAQLM9FhVXfPXhj45jC5bHLRqZXWsr QJbG18KagQ0hSLZ3kxmtpiR1rO1whxV/mcD/6iE8RwSA76JJeIc/v+uGhYlXGMkrsz YB/1Xx8IFjUxww3JU7zEdIgYv3eIsexX94DMRCEz1LVXmxpMmWXMw7lo6m57vNiYy5 MF8SeYrAGXOwWMK/+VnjmVrcyLyNsyW0HshQ5JvS6LSYTEQ6LFJHLig+SKKb1Pnm1z Vf75jBWFLxQ9A== From: Tejun Heo To: David Vernet , Andrea Righi , Changwoo Min Cc: Emil Tsalapatis , David Dai , sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org, Tejun Heo Subject: [PATCH 2/2] selftests/sched_ext: Check the cmask cid-form ops.enable() receives Date: Fri, 18 Sep 2026 14:28:38 -1000 Message-ID: <20260919002838.1960071-3-tj@kernel.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260919002838.1960071-1-tj@kernel.org> References: <20260919002838.1960071-1-tj@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit cid-form ops.enable() now hands the task's cmask to the scheduler and set_cmask() repeats it right after. Add a cid-form selftest that checks both against p->cpus_ptr, that they match each other, that the initial set_cmask() lands before set_weight() and before the task first becomes runnable, and that set_cmask() never precedes enable(), across class-switch enables, fork-path enables and live affinity changes. Signed-off-by: Tejun Heo --- tools/testing/selftests/sched_ext/Makefile | 1 + .../selftests/sched_ext/enable_cmask.bpf.c | 213 ++++++++++++++++++ .../selftests/sched_ext/enable_cmask.c | 138 ++++++++++++ 3 files changed, 352 insertions(+) create mode 100644 tools/testing/selftests/sched_ext/enable_cmask.bpf.c create mode 100644 tools/testing/selftests/sched_ext/enable_cmask.c diff --git a/tools/testing/selftests/sched_ext/Makefile b/tools/testing/selftests/sched_ext/Makefile index 49897727f535..4e06d0baaeec 100644 --- a/tools/testing/selftests/sched_ext/Makefile +++ b/tools/testing/selftests/sched_ext/Makefile @@ -169,6 +169,7 @@ auto-test-targets := \ ddsp_bogus_dsq_fail \ ddsp_vtimelocal_fail \ dsp_local_on \ + enable_cmask \ enq_select_cpu \ exit \ hotplug \ diff --git a/tools/testing/selftests/sched_ext/enable_cmask.bpf.c b/tools/testing/selftests/sched_ext/enable_cmask.bpf.c new file mode 100644 index 000000000000..bbbf989d2c69 --- /dev/null +++ b/tools/testing/selftests/sched_ext/enable_cmask.bpf.c @@ -0,0 +1,213 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * A cid-form scheduler checking the cmask cid-form ops.enable() receives: the + * header, every cid bit against p->cpus_ptr, and that set_cmask() follows with + * the same mask before set_weight() and before the task first becomes runnable, + * and never runs before enable(). + * + * Copyright (c) 2026 Tejun Heo + */ +#include + +#define MAX_CPUS 1024 + +char _license[] SEC("license") = "GPL"; + +struct { + __uint(type, BPF_MAP_TYPE_ARENA); + __uint(map_flags, BPF_F_MMAPABLE); + __uint(max_entries, 1 << 16); +} arena SEC(".maps"); + +struct task_ctx { + u64 enable_fp; /* fingerprint of the mask enable() received */ + bool enabled; + bool pending; /* enable() ran, the initial set_cmask() hasn't */ +}; + +struct { + __uint(type, BPF_MAP_TYPE_TASK_STORAGE); + __uint(map_flags, BPF_F_NO_PREALLOC); + __type(key, int); + __type(value, struct task_ctx); +} task_ctx_stor SEC(".maps"); + +u64 nr_enable, nr_initial_set_cmask, nr_set_cmask, nr_set_weight; +s32 bad_cid; +bool bad_want, bad_got; + +UEI_DEFINE(uei); + +static struct task_ctx *lookup_task_ctx(struct task_struct *p) +{ + struct task_ctx *tctx; + + tctx = bpf_task_storage_get(&task_ctx_stor, p, 0, 0); + if (!tctx) + scx_bpf_error("task_ctx lookup failed for %s[%d]", p->comm, p->pid); + return tctx; +} + +/* + * Verify @m's header and every cid bit against @p's cpumask and fingerprint the + * bits into @fp. Return 0 on success, -EINVAL on a bad header, -ENOENT on a cid + * without a cpu and -EIO on a bit mismatch with the details in @bad_*. + */ +static int check_mask(struct task_struct *p, const struct scx_cmask __arena *m, u64 *fp) +{ + u32 nr_cids = scx_bpf_nr_cids(); + u64 h = 0; + s32 cid; + + if (m->base || m->nr_cids != nr_cids) + return -EINVAL; + + bpf_for(cid, 0, MAX_CPUS) { + bool want, got; + s32 cpu; + + if (cid >= nr_cids) + break; + cpu = scx_bpf_cid_to_cpu(cid); + if (cpu < 0) + return -ENOENT; + want = bpf_cpumask_test_cpu(cpu, p->cpus_ptr); + got = cmask_test(cid, m); + if (want != got) { + bad_cid = cid; + bad_want = want; + bad_got = got; + return -EIO; + } + h = h * 31 + got; + } + + *fp = h; + return 0; +} + +s32 BPF_STRUCT_OPS_SLEEPABLE(enable_cmask_init_task, struct task_struct *p, + struct scx_init_task_args *args) +{ + if (!bpf_task_storage_get(&task_ctx_stor, p, 0, BPF_LOCAL_STORAGE_GET_F_CREATE)) + return -ENOMEM; + return 0; +} + +void BPF_STRUCT_OPS(enable_cmask_enable, struct task_struct *p, struct scx_enable_args *args) +{ + struct scx_cmask __arena *m = (struct scx_cmask __arena *)args->cmask_arena_addr; + struct task_ctx *tctx; + int ret; + + asm volatile("" :: "r"(&arena)); + tctx = lookup_task_ctx(p); + if (!tctx) + return; + + __sync_fetch_and_add(&nr_enable, 1); + if (tctx->enabled || tctx->pending) { + scx_bpf_error("enable: %s[%d] enabled twice", p->comm, p->pid); + return; + } + + ret = check_mask(p, m, &tctx->enable_fp); + if (ret) { + scx_bpf_error("enable: %s[%d] cmask check failed %d cid=%d want=%d got=%d", + p->comm, p->pid, ret, bad_cid, bad_want, bad_got); + return; + } + tctx->enabled = true; + tctx->pending = true; +} + +void BPF_STRUCT_OPS(enable_cmask_set_cmask, struct task_struct *p, + struct scx_cmask __arena *m) +{ + struct task_ctx *tctx; + u64 fp; + int ret; + + asm volatile("" :: "r"(&arena)); + tctx = lookup_task_ctx(p); + if (!tctx) + return; + + __sync_fetch_and_add(&nr_set_cmask, 1); + if (!tctx->enabled) { + scx_bpf_error("set_cmask: %s[%d] not enabled", p->comm, p->pid); + return; + } + + ret = check_mask(p, m, &fp); + if (ret) { + scx_bpf_error("set_cmask: %s[%d] cmask check failed %d cid=%d want=%d got=%d", + p->comm, p->pid, ret, bad_cid, bad_want, bad_got); + return; + } + + if (tctx->pending) { + if (fp != tctx->enable_fp) { + scx_bpf_error("set_cmask: %s[%d] initial mask differs from enable()", + p->comm, p->pid); + return; + } + tctx->pending = false; + __sync_fetch_and_add(&nr_initial_set_cmask, 1); + } +} + +void BPF_STRUCT_OPS(enable_cmask_set_weight, struct task_struct *p, u32 weight) +{ + struct task_ctx *tctx; + + tctx = lookup_task_ctx(p); + if (!tctx) + return; + + __sync_fetch_and_add(&nr_set_weight, 1); + if (tctx->pending) + scx_bpf_error("set_weight: %s[%d] before the initial set_cmask()", p->comm, + p->pid); +} + +void BPF_STRUCT_OPS(enable_cmask_runnable, struct task_struct *p, u64 enq_flags) +{ + struct task_ctx *tctx; + + tctx = lookup_task_ctx(p); + if (!tctx) + return; + + if (tctx->pending) + scx_bpf_error("runnable: %s[%d] before the initial set_cmask()", p->comm, + p->pid); +} + +void BPF_STRUCT_OPS(enable_cmask_disable, struct task_struct *p) +{ + struct task_ctx *tctx; + + tctx = lookup_task_ctx(p); + if (!tctx) + return; + + tctx->enabled = false; + tctx->pending = false; +} + +void BPF_STRUCT_OPS(enable_cmask_exit, struct scx_exit_info *ei) +{ + UEI_RECORD(uei, ei); +} + +SCX_OPS_CID_DEFINE(enable_cmask_ops, + .init_task = (void *)enable_cmask_init_task, + .enable = (void *)enable_cmask_enable, + .set_cmask = (void *)enable_cmask_set_cmask, + .set_weight = (void *)enable_cmask_set_weight, + .runnable = (void *)enable_cmask_runnable, + .disable = (void *)enable_cmask_disable, + .exit = (void *)enable_cmask_exit, + .flags = SCX_OPS_SWITCH_PARTIAL, + .name = "enable_cmask"); diff --git a/tools/testing/selftests/sched_ext/enable_cmask.c b/tools/testing/selftests/sched_ext/enable_cmask.c new file mode 100644 index 000000000000..556bcad4431d --- /dev/null +++ b/tools/testing/selftests/sched_ext/enable_cmask.c @@ -0,0 +1,138 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2026 Tejun Heo */ +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include "enable_cmask.bpf.skel.h" +#include "scx_test.h" + +#define SCHED_EXT 7 +#define NR_CHILDREN 8 +#define MAX_CPUS 1024 + +static int cpus[MAX_CPUS]; +static int nr_cpus; + +static void spin_ms(int ms) +{ + struct timespec start, now; + + clock_gettime(CLOCK_MONOTONIC, &start); + do { + clock_gettime(CLOCK_MONOTONIC, &now); + } while ((now.tv_sec - start.tv_sec) * 1000 + + (now.tv_nsec - start.tv_nsec) / 1000000 < ms); +} + +static int pin(pid_t pid, int idx) +{ + cpu_set_t set; + + CPU_ZERO(&set); + CPU_SET(cpus[idx % nr_cpus], &set); + return sched_setaffinity(pid, sizeof(set), &set); +} + +/* + * Pin, switch to SCHED_EXT for a class-switch enable, fork a grandchild that + * inherits the policy for a fork-path enable, then change affinity a few times + * while running for set_cmask() on live tasks. + */ +static int child(int idx) +{ + struct sched_param param = {}; + int i, status; + pid_t pid; + + if (pin(0, idx) || sched_setscheduler(0, SCHED_EXT, ¶m)) + return 1; + + pid = fork(); + if (pid < 0) + return 1; + if (!pid) { + spin_ms(20); + return 0; + } + + for (i = 1; i <= 4; i++) { + if (pin(0, idx + i)) + return 1; + spin_ms(5); + } + + return waitpid(pid, &status, 0) == pid && !status ? 0 : 1; +} + +static enum scx_test_status run(void *ctx) +{ + struct enable_cmask *skel; + struct bpf_link *link; + pid_t pids[NR_CHILDREN]; + cpu_set_t set; + int i, status, failed = 0; + + if (!__COMPAT_struct_has_field("scx_enable_args", "cmask_arena_addr")) + return SCX_TEST_SKIP; + + SCX_FAIL_IF(sched_getaffinity(0, sizeof(set), &set), "Failed to read affinity"); + for (i = 0; i < MAX_CPUS && i < CPU_SETSIZE; i++) + if (CPU_ISSET(i, &set)) + cpus[nr_cpus++] = i; + if (nr_cpus < 2) + return SCX_TEST_SKIP; + + skel = enable_cmask__open(); + SCX_FAIL_IF(!skel, "Failed to open"); + SCX_ENUM_INIT(skel); + SCX_FAIL_IF(enable_cmask__load(skel), "Failed to load skel"); + + link = bpf_map__attach_struct_ops(skel->maps.enable_cmask_ops); + SCX_FAIL_IF(!link, "Failed to attach struct_ops"); + + for (i = 0; i < NR_CHILDREN; i++) { + pids[i] = fork(); + SCX_FAIL_IF(pids[i] < 0, "Failed to fork"); + if (!pids[i]) + exit(child(i)); + } + + /* affinity changes from the outside race with the children's own */ + for (i = 0; i < NR_CHILDREN; i++) + pin(pids[i], i + NR_CHILDREN); + + for (i = 0; i < NR_CHILDREN; i++) { + if (waitpid(pids[i], &status, 0) != pids[i] || status) + failed++; + } + + bpf_link__destroy(link); + + SCX_EQ(skel->data->uei.kind, EXIT_KIND(SCX_EXIT_UNREG)); + SCX_EQ(failed, 0); + SCX_GE(skel->bss->nr_enable, 2 * NR_CHILDREN); + SCX_EQ(skel->bss->nr_initial_set_cmask, skel->bss->nr_enable); + SCX_GT(skel->bss->nr_set_cmask, skel->bss->nr_initial_set_cmask); + SCX_GE(skel->bss->nr_set_weight, skel->bss->nr_enable); + printf("enable=%lu initial_set_cmask=%lu set_cmask=%lu set_weight=%lu\n", + (unsigned long)skel->bss->nr_enable, + (unsigned long)skel->bss->nr_initial_set_cmask, + (unsigned long)skel->bss->nr_set_cmask, + (unsigned long)skel->bss->nr_set_weight); + + enable_cmask__destroy(skel); + return SCX_TEST_PASS; +} + +struct scx_test enable_cmask = { + .name = "enable_cmask", + .description = "Check the cid-form ops.enable() cmask and the set_cmask() after it", + .run = run, +}; +REGISTER_SCX_TEST(&enable_cmask) -- 2.55.0