tools/testing/selftests/sched_ext/hotplug.c

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Copyright (c) 2024 Meta Platforms, Inc. and affiliates.
   4  * Copyright (c) 2024 David Vernet <[email protected]>
   5  */
   6 #include <bpf/bpf.h>
   7 #include <sched.h>
   8 #include <scx/common.h>
   9 #include <sched.h>
  10 #include <sys/wait.h>
  11 #include <unistd.h>
  12
  13 #include "hotplug_test.h"
  14 #include "hotplug.bpf.skel.h"
  15 #include "scx_test.h"
  16 #include "util.h"
  17
  18 const char *online_path = "/sys/devices/system/cpu/cpu1/online";
  19
  20 static bool is_cpu_online(void)
  21 {
  22         return file_read_long(online_path) > 0;
  23 }
  24
  25 static void toggle_online_status(bool online)
  26 {
  27         long val = online ? 1 : 0;
  28         int ret;
  29
  30         ret = file_write_long(online_path, val);
  31         if (ret != 0)
  32                 fprintf(stderr, "Failed to bring CPU %s (%s)",
  33                         online ? "online" : "offline", strerror(errno));
  34 }
  35
  36 static enum scx_test_status setup(void **ctx)
  37 {
  38         if (!is_cpu_online())
  39                 return SCX_TEST_SKIP;
  40
  41         return SCX_TEST_PASS;
  42 }
  43
  44 static enum scx_test_status test_hotplug(bool onlining, bool cbs_defined)
  45 {
  46         struct hotplug *skel;
  47         struct bpf_link *link;
  48         long kind, code;
  49
  50         SCX_ASSERT(is_cpu_online());
  51
  52         skel = hotplug__open_and_load();
  53         SCX_ASSERT(skel);
  54
  55         /* Testing the offline -> online path, so go offline before starting */
  56         if (onlining)
  57                 toggle_online_status(0);
  58
  59         if (cbs_defined) {
  60                 kind = SCX_KIND_VAL(SCX_EXIT_UNREG_BPF);
  61                 code = SCX_ECODE_VAL(SCX_ECODE_ACT_RESTART) | HOTPLUG_EXIT_RSN;
  62                 if (onlining)
  63                         code |= HOTPLUG_ONLINING;
  64         } else {
  65                 kind = SCX_KIND_VAL(SCX_EXIT_UNREG_KERN);
  66                 code = SCX_ECODE_VAL(SCX_ECODE_ACT_RESTART) |
  67                        SCX_ECODE_VAL(SCX_ECODE_RSN_HOTPLUG);
  68         }
  69
  70         if (cbs_defined)
  71                 link = bpf_map__attach_struct_ops(skel->maps.hotplug_cb_ops);
  72         else
  73                 link = bpf_map__attach_struct_ops(skel->maps.hotplug_nocb_ops);
  74
  75         if (!link) {
  76                 SCX_ERR("Failed to attach scheduler");
  77                 hotplug__destroy(skel);
  78                 return SCX_TEST_FAIL;
  79         }
  80
  81         toggle_online_status(onlining ? 1 : 0);
  82
  83         while (!UEI_EXITED(skel, uei))
  84                 sched_yield();
  85
  86         SCX_EQ(skel->data->uei.kind, kind);
  87         SCX_EQ(UEI_REPORT(skel, uei), code);
  88
  89         if (!onlining)
  90                 toggle_online_status(1);
  91
  92         bpf_link__destroy(link);
  93         hotplug__destroy(skel);
  94
  95         return SCX_TEST_PASS;
  96 }
  97
  98 static enum scx_test_status test_hotplug_attach(void)
  99 {
 100         struct hotplug *skel;
 101         struct bpf_link *link;
 102         enum scx_test_status status = SCX_TEST_PASS;
 103         long kind, code;
 104
 105         SCX_ASSERT(is_cpu_online());
 106         SCX_ASSERT(scx_hotplug_seq() > 0);
 107
 108         skel = SCX_OPS_OPEN(hotplug_nocb_ops, hotplug);
 109         SCX_ASSERT(skel);
 110
 111         SCX_OPS_LOAD(skel, hotplug_nocb_ops, hotplug, uei);
 112
 113         /*
 114          * Take the CPU offline to increment the global hotplug seq, which
 115          * should cause attach to fail due to us setting the hotplug seq above
 116          */
 117         toggle_online_status(0);
 118         link = bpf_map__attach_struct_ops(skel->maps.hotplug_nocb_ops);
 119
 120         toggle_online_status(1);
 121
 122         SCX_ASSERT(link);
 123         while (!UEI_EXITED(skel, uei))
 124                 sched_yield();
 125
 126         kind = SCX_KIND_VAL(SCX_EXIT_UNREG_KERN);
 127         code = SCX_ECODE_VAL(SCX_ECODE_ACT_RESTART) |
 128                SCX_ECODE_VAL(SCX_ECODE_RSN_HOTPLUG);
 129         SCX_EQ(skel->data->uei.kind, kind);
 130         SCX_EQ(UEI_REPORT(skel, uei), code);
 131
 132         bpf_link__destroy(link);
 133         hotplug__destroy(skel);
 134
 135         return status;
 136 }
 137
 138 static enum scx_test_status run(void *ctx)
 139 {
 140
 141 #define HP_TEST(__onlining, __cbs_defined) ({                           \
 142         if (test_hotplug(__onlining, __cbs_defined) != SCX_TEST_PASS)   \
 143                 return SCX_TEST_FAIL;                                   \
 144 })
 145
 146         HP_TEST(true, true);
 147         HP_TEST(false, true);
 148         HP_TEST(true, false);
 149         HP_TEST(false, false);
 150
 151 #undef HP_TEST
 152
 153         return test_hotplug_attach();
 154 }
 155
 156 static void cleanup(void *ctx)
 157 {
 158         toggle_online_status(1);
 159 }
 160
 161 struct scx_test hotplug_test = {
 162         .name = "hotplug",
 163         .description = "Verify hotplug behavior",
 164         .setup = setup,
 165         .run = run,
 166         .cleanup = cleanup,
 167 };
 168 REGISTER_SCX_TEST(&hotplug_test)