From: Emil Tsalapatis Date: Fri, 5 Jun 2026 22:20:20 +0000 (-0400) Subject: selftests/bpf: libarena: parallel test harness and spmc parallel selftest X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=42998f819256ef272b6a445310e2b64a3729a139;p=thirdparty%2Flinux.git selftests/bpf: libarena: parallel test harness and spmc parallel selftest Add a parallel test for the SPMC Lev-Chase workstealing queue. The queue is built to be wait-free even when there are multiple consumers, and the parallel selftest provides a signal on whether the queue behaves correctly when stress tested. To support the test, this patch includes a test harness for parallel selftests. The spmc selftest acts as an example of the naming and other conventions expected by the harness. Signed-off-by: Emil Tsalapatis Link: https://lore.kernel.org/r/20260605222020.5231-4-emil@etsalapatis.com Signed-off-by: Alexei Starovoitov --- diff --git a/tools/testing/selftests/bpf/libarena/include/libarena/userspace.h b/tools/testing/selftests/bpf/libarena/include/libarena/userspace.h index 88b68ac73cca..fc27a4bcf5d7 100644 --- a/tools/testing/selftests/bpf/libarena/include/libarena/userspace.h +++ b/tools/testing/selftests/bpf/libarena/include/libarena/userspace.h @@ -32,6 +32,12 @@ static inline bool libarena_is_asan_test_prog(const char *name) return strstr(name, "asan_test") == name; } +static inline bool libarena_is_parallel_test_prog(const char *name) +{ + return strstr(name, "parallel_test") == name; +} + + static inline int libarena_run_prog_args(int prog_fd, void *args, size_t argsize) { LIBBPF_OPTS(bpf_test_run_opts, opts); diff --git a/tools/testing/selftests/bpf/libarena/selftests/test_parallel_spmc.bpf.c b/tools/testing/selftests/bpf/libarena/selftests/test_parallel_spmc.bpf.c new file mode 100644 index 000000000000..981c845e2d15 --- /dev/null +++ b/tools/testing/selftests/bpf/libarena/selftests/test_parallel_spmc.bpf.c @@ -0,0 +1,673 @@ +// SPDX-License-Identifier: LGPL-2.1 OR BSD-2-Clause + +#include + +#include + +#include +#include + +#define TEST_SPMC_THREADS 4 +#define TEST_SPMC_STEALERS (TEST_SPMC_THREADS - 1) + +/* + * The test requires the stealers/owners to sometimes quiesce + * before continuing the benchmark. Normally we'd use something + * like a condition variable, but since the benchmark is short-lived + * and operations are wait-free we just spin around the quiescence + * point instead. If we time out, we just fail the benchmark. + */ +#define TEST_SPMC_SYNC_SPINS (1U << 18) + +/* + * We track all the values we retrieve from the queue + * to get some guarantee we're, not corrupting data, + * e.g., accidentally reusing a past value from a slot. + */ +#define TEST_SPMC_MAX_VALUES (1024) +static u64 __arena seen[TEST_SPMC_MAX_VALUES]; + +/* The single spmc queue for the benchmark. */ +static struct spmc __arena *spmc; + +/* Owner and stealer epochs. We define the , */ +static volatile u64 owner_epoch; +static volatile u64 stealer_epoch; + +/* Map owner epochs to stealer epochs (simply scale by # of stealers). */ +#define STEALER_EPOCH(owner_epoch) ((owner_epoch) * TEST_SPMC_STEALERS) + +/* Global abort switch. If any thread fails, all others exit ASAP. */ +static volatile bool test_abort; + +/* + * Counters useful for ensuring conservation of pushes/pops of unique values + * (we're not stealing/popping more/fewer items than were pushed). + */ +static volatile u64 expected_total; +static volatile u64 total_seen; + +/* Measure how many pops and steals we've made (irrespective of retrieved value). */ +static volatile u64 pops; +static volatile u64 steals; + +/* Used for the resize selftest, see below. */ +static volatile u64 stealers_started; + +/* Used for the mixed selftest, see below. */ +static volatile u64 round_steals; + +/* + * We have multiple stealers and a single owner. We sometimes want the owner + * to successfully outproduce the stealers, we add a busy loop in them. + */ +#define TEST_SPMC_WASTE_ROUNDS (1024) + +/* + * The spmc data structure depends on the runtime fully + * supporting acquire/release semantics, which is not + * the case for all architectures. + */ +#if defined(ENABLE_ATOMICS_TESTS) && \ + (defined(__TARGET_ARCH_arm64) || defined(__TARGET_ARCH_x86) || \ + (defined(__TARGET_ARCH_riscv) && __riscv_xlen == 64)) +static bool spmc_tests_enabled(void) +{ + return true; +} +#else +static bool spmc_tests_enabled(void) +{ + return false; +} +#endif + +/* + * Scaffolding for each parallel test. Each test has setup/teardown, + * a single owner thread that owns the queue, and TEST_SPMC_STEALER + * threads that try to steal. + */ +#define DEFINE_PARALLEL_SPMC_TEST(prefix, expected_total) \ + SEC("syscall") int parallel_test_spmc_##prefix##__enabled(void) \ + { \ + return spmc_tests_enabled() ? 0 : -EOPNOTSUPP; \ + } \ + SEC("syscall") int parallel_test_spmc_##prefix##__init(void) \ + { \ + return spmc_common_init(expected_total); \ + } \ + SEC("syscall") int parallel_test_spmc_##prefix##__fini(void) \ + { \ + return spmc_common_fini(); \ + } \ + SEC("syscall") int parallel_test_spmc_##prefix##__0(void) \ + { \ + return spmc_##prefix##_owner(); \ + } \ + SEC("syscall") int parallel_test_spmc_##prefix##__1(void) \ + { \ + return spmc_##prefix##_stealer(); \ + } \ + SEC("syscall") int parallel_test_spmc_##prefix##__2(void) \ + { \ + return spmc_##prefix##_stealer(); \ + } \ + SEC("syscall") int parallel_test_spmc_##prefix##__3(void) \ + { \ + return spmc_##prefix##_stealer(); \ + } + +static int spmc_common_init(u64 total) +{ + u64 i; + + if (total > TEST_SPMC_MAX_VALUES) + return -E2BIG; + + owner_epoch = 0; + stealer_epoch = 0; + test_abort = false; + expected_total = total; + total_seen = 0; + pops = 0; + steals = 0; + stealers_started = 0; + round_steals = 0; + + for (i = zero; i < TEST_SPMC_MAX_VALUES && can_loop; i++) + seen[i] = 0; + + spmc = spmc_create(); + if (!spmc) + return -ENOMEM; + + return 0; +} + +static int spmc_common_fini(void) +{ + int ret; + + ret = spmc_destroy(spmc); + spmc = NULL; + + return ret; +} + +__weak +int spmc_quiesce_on_owner(u64 epoch) +{ + u64 i; + + bpf_for(i, 0, TEST_SPMC_SYNC_SPINS) { + if (test_abort) + return -EINTR; + if (smp_load_acquire(&owner_epoch) >= epoch) + return 0; + } + + test_abort = true; + + return -ETIMEDOUT; +} + +__weak +int spmc_quiesce_on_stealer(u64 epoch) +{ + u64 target, cur; + unsigned int i; + int err = -ETIMEDOUT; + + target = STEALER_EPOCH(epoch); + bpf_for(i, 0, TEST_SPMC_SYNC_SPINS) { + + if (test_abort) { + err = -EINTR; + break; + } + + cur = smp_load_acquire(&stealer_epoch); + if (cur > target) { + err = -EINVAL; + test_abort = true; + break; + } + + if (cur == target) + return 0; + } + + test_abort = true; + + return err; +} + +static int spmc_update_stats(u64 val, bool owner) +{ + u64 total; + + total = expected_total; + if (val >= total || val >= TEST_SPMC_MAX_VALUES) { + test_abort = true; + return -EINVAL; + } + + if (__sync_fetch_and_add(&seen[val], 1) != 0) { + test_abort = true; + return -EINVAL; + } + + __sync_fetch_and_add(&total_seen, 1); + if (owner) + __sync_fetch_and_add(&pops, 1); + else + __sync_fetch_and_add(&steals, 1); + + return 0; +} + +static int spmc_validate_owner_empty(void) +{ + u64 val; + int ret; + + ret = spmc_owned_remove(spmc, &val); + if (ret != -ENOENT) { + test_abort = true; + /* Change a 0 return value into -EINVAL. */ + return ret ?: -EINVAL; + } + + return 0; +} + +__weak +int spmc_validate_all_seen(void) +{ + u64 i, total; + + total = expected_total; + if (total_seen != total) + goto err; + + if (pops + steals != total) + goto err; + + for (i = zero; i < total && can_loop; i++) { + if (seen[i % TEST_SPMC_MAX_VALUES] != 1) + goto err; + } + + return 0; + +err: + test_abort = true; + + return -EINVAL; +} + +/* + * Single value benchmark. The owner adds an item then races with + * the stealers for it. This way directly race between owner and + * stealers on the same slot. + */ + + +#define TEST_SPMC_SINGLEVAL_ITERS (64) + +__weak +int spmc_singleval_tryconsume(u64 expected, bool steal) +{ + u64 val; + int ret; + + while (can_loop) { + if (steal) + ret = spmc_steal(spmc, &val); + else + ret = spmc_owned_remove(spmc, &val); + + /* Success. Update and validate. */ + if (!ret) { + if (val != expected) + return -EINVAL; + + ret = spmc_update_stats(val, !steal); + if (ret) + return ret; + + return 0; + } + + /* + * If we got -ENOENT, the queue is empty + * and we're good to go. + */ + if (ret != -EAGAIN) + return (ret == -ENOENT) ? 0 : ret; + } + + /* Impossible. */ + return -EINVAL; +} + +static int spmc_singleval_owner(void) +{ + int ret; + u64 i; + + for (i = zero; i < TEST_SPMC_SINGLEVAL_ITERS && can_loop; i++) { + ret = spmc_quiesce_on_stealer(i); + if (ret) + goto err; + + ret = spmc_owned_add(spmc, i); + if (ret) + goto err; + + __sync_fetch_and_add(&owner_epoch, 1); + + ret = spmc_singleval_tryconsume(i, false); + if (ret) + goto err; + + ret = spmc_quiesce_on_stealer(i + 1); + if (ret) + goto err; + } + + ret = spmc_validate_owner_empty(); + if (ret) + return ret; + + return spmc_validate_all_seen(); + +err: + test_abort = true; + return -EINVAL; +} + +static int spmc_singleval_stealer(void) +{ + int ret; + u64 i; + + for (i = zero; i < TEST_SPMC_SINGLEVAL_ITERS && can_loop; i++) { + ret = spmc_quiesce_on_owner(i + 1); + if (ret) + goto err; + + ret = spmc_singleval_tryconsume(i, true); + if (ret) + goto err; + + __sync_fetch_and_add(&stealer_epoch, 1); + } + + return 0; + +err: + test_abort = true; + return -EINVAL; +} + +DEFINE_PARALLEL_SPMC_TEST(singleval, TEST_SPMC_SINGLEVAL_ITERS) + +/* + * The resize test. Force a resize from the owner even while the stealers + * are trying to consume. Then make sure the queue is still consistent + * after the resize. + * + * The owner _doesn't_ consume from the queue. The test makes sure that + * switching the array from underneath the stealers works. + */ + +/* Force 2 resizes (since the rate of resize is logarithmic). */ +#define TEST_SPMC_RESIZE_ORDER (2) +#define TEST_SPMC_RESIZE_PREFILL ((SPMC_ARR_BASESZ << TEST_SPMC_RESIZE_ORDER) - 1) + +/* */ +#define TEST_SPMC_RESIZE_TAIL (SPMC_ARR_BASESZ << TEST_SPMC_RESIZE_ORDER) +#define TEST_SPMC_RESIZE_TOTAL (TEST_SPMC_RESIZE_PREFILL + TEST_SPMC_RESIZE_TAIL) + +__weak +int spmc_wait_for_stealers_to_start(u64 target) +{ + u64 i; + + bpf_for(i, 0, TEST_SPMC_SYNC_SPINS) { + if (test_abort) + return -EINTR; + if (READ_ONCE(stealers_started) >= target) + return 0; + } + + test_abort = true; + + return -ETIMEDOUT; +} + +__weak +void spmc_waste_time(void) +{ + int i; + int j; + + for (i = zero; i < TEST_SPMC_WASTE_ROUNDS && can_loop; i++) { + /* Random computation. */ + WRITE_ONCE(j, i * 17 + 23); + } +} + +static int spmc_resize_owner(void) +{ + bool resized = false; + u64 i; + int ret; + + /* Get a head start vs the consumers. */ + for (i = zero; i < TEST_SPMC_RESIZE_PREFILL && can_loop; i++) { + ret = spmc_owned_add(spmc, i); + if (ret) { + test_abort = true; + return ret; + } + } + + __sync_fetch_and_add(&owner_epoch, 1); + + /* Wait for stealers to start then start racing. */ + ret = spmc_wait_for_stealers_to_start(TEST_SPMC_STEALERS); + if (ret) + return ret; + + for (i = TEST_SPMC_RESIZE_PREFILL; i < TEST_SPMC_RESIZE_TOTAL && can_loop; i++) { + ret = spmc_owned_add(spmc, i); + if (ret) { + test_abort = true; + return ret; + } + + if (spmc->cur->order > TEST_SPMC_RESIZE_ORDER) + resized = true; + } + + /* Did we get to resize while racing/ */ + if (!resized) { + test_abort = true; + return -153; + } + + /* + * Wait for the stealers to drain and make sure + * we didn't lose any items along the way. + */ + __sync_fetch_and_add(&owner_epoch, 1); + + ret = spmc_quiesce_on_stealer(1); + if (ret) + return ret; + + ret = spmc_validate_owner_empty(); + if (ret) + return ret; + + return spmc_validate_all_seen(); +} + +static int spmc_resize_stealer(void) +{ + bool owner_done = false; + u64 val; + int ret; + + arena_subprog_init(); + + ret = spmc_quiesce_on_owner(1); + if (ret) + return ret; + + __sync_fetch_and_add(&stealers_started, 1); + + while (can_loop) { + spmc_waste_time(); + if (test_abort) + return -EINTR; + + ret = spmc_steal(spmc, &val); + if (!ret) { + ret = spmc_update_stats(val, false); + if (ret) + return ret; + continue; + } + + if (ret == -EAGAIN) + continue; + + if (ret == -ENOENT) { + if (owner_done) + break; + owner_done = owner_epoch >= 2; + continue; + } + + test_abort = true; + return ret; + } + + __sync_fetch_and_add(&stealer_epoch, 1); + + return 0; +} + +DEFINE_PARALLEL_SPMC_TEST(resize, TEST_SPMC_RESIZE_TOTAL) + +/* + * The burst benchmark. The owner generates data all at once, + * then waits for the stealers to steal half then starts removing + * items until the queue empties. The owner also makes sure the + * item order is not jumbled. + */ + +#define TEST_SPMC_BURST_ROUNDS (4) +#define TEST_SPMC_BURST_BURST (64) +#define TEST_SPMC_BURST_TOTAL (TEST_SPMC_BURST_ROUNDS * TEST_SPMC_BURST_BURST) +#define TEST_SPMC_BURST_STEAL_TARGET (TEST_SPMC_BURST_BURST / 2) + +static int spmc_wait_for_round_steals(u64 target) +{ + u64 i; + + arena_subprog_init(); + + bpf_for(i, 0, TEST_SPMC_SYNC_SPINS) { + if (test_abort) + return -EINTR; + if (round_steals >= target) + return 0; + } + + test_abort = true; + + return -ETIMEDOUT; +} + +__weak int +spmc_burst_owner_round(u64 round) +{ + u64 i, base, stolen, expected, val; + int ret; + + base = round * TEST_SPMC_BURST_BURST; + round_steals = 0; + + for (i = zero; i < TEST_SPMC_BURST_BURST && can_loop; i++) { + ret = spmc_owned_add(spmc, base + i); + if (ret) + return ret; + } + + __sync_fetch_and_add(&owner_epoch, 1); + + ret = spmc_wait_for_round_steals(TEST_SPMC_BURST_STEAL_TARGET); + if (ret == -EINTR || ret == -ETIMEDOUT) + return ret; + + __sync_fetch_and_add(&owner_epoch, 1); + + ret = spmc_quiesce_on_stealer(round + 1); + if (ret) + return ret; + + stolen = round_steals; + if (stolen > TEST_SPMC_BURST_BURST) + return -EINVAL; + + for (i = zero; i < TEST_SPMC_BURST_BURST - stolen && can_loop; i++) { + ret = spmc_owned_remove(spmc, &val); + if (ret) + return ret; + + expected = base + TEST_SPMC_BURST_BURST - 1 - i; + if (val != expected) + return -EINVAL; + + ret = spmc_update_stats(val, true); + if (ret) { + test_abort = true; + return -EINVAL; + } + } + + ret = spmc_validate_owner_empty(); + if (ret) + return ret; + + return 0; +} + +static int spmc_burst_owner(void) +{ + u64 round; + int ret; + + arena_subprog_init(); + + for (round = zero; round < TEST_SPMC_BURST_ROUNDS && can_loop; round++) { + ret = spmc_burst_owner_round(round); + if (ret) + goto err; + } + + return spmc_validate_all_seen(); + +err: + test_abort = true; + return -EINVAL; +} + +static int spmc_burst_stealer(void) +{ + u64 round, val, active_epoch; + int ret; + + arena_subprog_init(); + + for (round = zero; round < TEST_SPMC_BURST_ROUNDS && can_loop; round++) { + active_epoch = round * 2 + 1; + + /* + * Wait till the owner prefills the queue then + * start stealing. + */ + ret = spmc_quiesce_on_owner(active_epoch); + if (ret) + return ret; + + while (owner_epoch == active_epoch && can_loop) { + if (test_abort) + return -EINTR; + + ret = spmc_steal(spmc, &val); + if (!ret) { + ret = spmc_update_stats(val, false); + if (ret) + return ret; + __sync_fetch_and_add(&round_steals, 1); + continue; + } + if (ret == -EAGAIN || ret == -ENOENT) + continue; + + test_abort = true; + return ret; + } + + __sync_fetch_and_add(&stealer_epoch, 1); + } + + return 0; +} + +DEFINE_PARALLEL_SPMC_TEST(burst, TEST_SPMC_BURST_TOTAL) diff --git a/tools/testing/selftests/bpf/prog_tests/libarena.c b/tools/testing/selftests/bpf/prog_tests/libarena.c index 81bdb084c271..61ea68dce410 100644 --- a/tools/testing/selftests/bpf/prog_tests/libarena.c +++ b/tools/testing/selftests/bpf/prog_tests/libarena.c @@ -27,6 +27,177 @@ static void run_libarena_test(struct libarena *skel, struct bpf_program *prog, } +static void *run_libarena_parallel_prog(void *arg) +{ + struct bpf_program *prog = arg; + + return (void *)(long)libarena_run_prog(bpf_program__fd(prog)); +} + +/* Max suffix is ceil((lg 2^32) / (lg 10)) + sizeof("__") = 10 + 2 = 12. */ +#define MAX_PARTEST_SUFFIX (12) +#define MAX_PARTEST_NAME (1024) +#define MAX_PARTEST_PREFIX (MAX_PARTEST_NAME - MAX_PARTEST_SUFFIX) + +static int run_libarena_parallel_fini(struct libarena *skel, const char *name, + size_t prefixlen) +{ + char tdname[MAX_PARTEST_NAME]; + struct bpf_program *fini_prog; + int ret; + + ret = snprintf(tdname, sizeof(tdname), "%.*s__fini", (int)prefixlen, name); + if (!ASSERT_LT(ret, sizeof(tdname), "partest fini name")) + return -ENAMETOOLONG; + + fini_prog = bpf_object__find_program_by_name(skel->obj, tdname); + if (!ASSERT_TRUE(fini_prog, "partest fini prog")) + return -ENOENT; + + ret = libarena_run_prog(bpf_program__fd(fini_prog)); + ASSERT_OK(ret, tdname); + + return ret; +} + +static int run_libarena_parallel_test_workers(struct libarena *skel, + const char *name, size_t prefixlen) +{ + pthread_t *threads = NULL, *tmp_threads; + char tdname[MAX_PARTEST_NAME]; + struct bpf_program *tdprog; + uint32_t nthreads; + void *thread_ret; + int ret, err = 0; + int i; + + for (nthreads = 0; nthreads < UINT_MAX; nthreads++) { + ret = snprintf(tdname, sizeof(tdname), "%.*s__%u", (int)prefixlen, + name, nthreads); + if (!ASSERT_LT(ret, sizeof(tdname), "test worker name")) { + err = -ENAMETOOLONG; + break; + } + + /* + * We enumerate the worker threads for a given test with __0, __1, + * and so on. The suffixes always start from 0 and are contiguous, + * so if we don't find a program with the requested name we have + * discovered all available worker programs. + */ + tdprog = bpf_object__find_program_by_name(skel->obj, tdname); + if (!tdprog) + break; + + /* Bump the alloc array to accommodate the new thread. */ + tmp_threads = realloc(threads, (nthreads + 1) * sizeof(*threads)); + if (!ASSERT_TRUE(tmp_threads, "realloc")) { + err = -ENOMEM; + break; + } + threads = tmp_threads; + + ret = pthread_create(&threads[nthreads], NULL, + run_libarena_parallel_prog, + tdprog); + if (!ASSERT_OK(ret, "pthread_create")) { + err = ret; + break; + } + } + + + for (i = 0; i < nthreads; i++) { + ret = pthread_join(threads[i], &thread_ret); + if (!ASSERT_OK(ret, "pthread_join")) { + err = err ?: ret; + continue; + } + + err = err ?: (long)thread_ret; + } + + free(threads); + + return err; +} + +static bool libarena_parallel_test_enabled(struct libarena *skel, + const char *prefix, + size_t prefixlen) +{ + struct bpf_program *prog; + char progname[MAX_PARTEST_NAME]; + int ret; + + ret = snprintf(progname, sizeof(progname), "%.*s__enabled", (int)prefixlen, + prefix); + if (!ASSERT_LT(ret, sizeof(progname), "partest enabled name")) + return false; + + prog = bpf_object__find_program_by_name(skel->obj, progname); + if (!prog) + return true; + + ret = libarena_run_prog(bpf_program__fd(prog)); + if (ret == -EOPNOTSUPP) + return false; + if (!ASSERT_OK(ret, progname)) + return false; + return true; +} + +static void run_libarena_parallel_test(struct libarena *skel, struct bpf_program *prog, + const char *name) +{ + char testname[MAX_PARTEST_NAME]; + size_t prefixlen; + const char *pos; + int ret; + + /* + * We annotate the initialization prog with __init. If the current prog does + * not match, it is one of the parallel threads instead and is ignored. + * + * We assume the test writer knows what they are doing and do not add __init + * randomly in the middle of a test name. + */ + pos = strstr(name, "__init"); + if (!pos) + return; + + prefixlen = pos - name; + if (!ASSERT_LT(prefixlen, MAX_PARTEST_PREFIX, "partest prefix too long")) + return; + + /* The name of the test without the __init suffix. Looks nicer in the test log. */ + ret = snprintf(testname, sizeof(testname), "%.*s", (int)prefixlen, name); + if (!ASSERT_LT(ret, sizeof(testname), "partest test name")) + return; + + if (!test__start_subtest(testname)) + return; + + if (!libarena_parallel_test_enabled(skel, testname, prefixlen)) { + test__skip(); + return; + } + + ret = libarena_run_prog(bpf_program__fd(skel->progs.arena_buddy_reset)); + if (!ASSERT_OK(ret, "arena_buddy_reset")) + return; + + ret = libarena_run_prog(bpf_program__fd(prog)); + if (!ASSERT_OK(ret, testname)) + return; + + ret = run_libarena_parallel_test_workers(skel, name, prefixlen); + + ASSERT_OK(ret, testname); + + run_libarena_parallel_fini(skel, name, prefixlen); +} + void test_libarena(void) { struct arena_alloc_reserve_args args; @@ -52,6 +223,22 @@ void test_libarena(void) bpf_object__for_each_program(prog, skel->obj) { const char *name = bpf_program__name(prog); + /* + * Handle parallel test progs separately. For those + * progs it's not a matter of test/skip, because each + * parallel test prog includes an initialization prog + * and a set of progs to be run in parallel. For the + * latter we do not record them as skipped or run, + * because we run them all at once when we come across + * the initialization prog. For more details on how we + * discover the progs see the comment on + * run_libarena_parallel_test. + */ + if (libarena_is_parallel_test_prog(name)) { + run_libarena_parallel_test(skel, prog, name); + continue; + } + if (!libarena_is_test_prog(name)) continue;