Hi,
===== START ===== TEST: enq_last_no_enq_fails DESCRIPTION: Verify we fail to load a scheduler if we specify the SCX_OPS_ENQ_LAST flag without defining ops.enqueue() OUTPUT: ERR: enq_last_no_enq_fails.c:35 Incorrectly succeeded in to attaching scheduler not ok 2 enq_last_no_enq_fails # ===== END =====
Above selftest fails even when BPF scheduler is not loaded into the kernel.
Below is snippet from the dmesg verifing bpf program was not loaded: sched_ext: enq_last_no_enq_fails: SCX_OPS_ENQ_LAST requires ops.enqueue() to be implemented scx_ops_enable.isra.0+0xde8/0xe30 bpf_struct_ops_link_create+0x1ac/0x240 link_create+0x178/0x400 __sys_bpf+0x7ac/0xd50 sys_bpf+0x2c/0x70 system_call_exception+0x148/0x310 system_call_vectored_common+0x15c/0x2ec sched_ext: "enq_select_cpu_fails" does not implement cgroup cpu.weight sched_ext: BPF scheduler "enq_select_cpu_fails" enabled sched_ext: BPF scheduler "enq_select_cpu_fails" disabled (runtime error)
static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link) { ... ret = validate_ops(ops); if (ret) goto err_disable; ... err_disable: mutex_unlock(&scx_ops_enable_mutex); /* * Returning an error code here would not pass all the error information * to userspace. Record errno using scx_ops_error() for cases * scx_ops_error() wasn't already invoked and exit indicating success so * that the error is notified through ops.exit() with all the details. * * Flush scx_ops_disable_work to ensure that error is reported before * init completion. */ scx_ops_error("scx_ops_enable() failed (%d)", ret); kthread_flush_work(&scx_ops_disable_work); return 0; }
validate_ops() correctly reports the error, but err_disable path ultimately returns with a value of zero
from: enq_last_no_enq_fails.c static enum scx_test_status run(void *ctx) { struct enq_last_no_enq_fails *skel = ctx; struct bpf_link *link;
link = bpf_map__attach_struct_ops(skel->maps.enq_last_no_enq_fails_ops); if (link) { SCX_ERR("Incorrectly succeeded in to attaching scheduler"); return SCX_TEST_FAIL; }
bpf_link__destroy(link);
return SCX_TEST_PASS; }