Add a test case to verify the atomic update of existing element in hash map. The test proceeds in three steps: 1) fill the map with keys in the range [0, 63] 2) create 8 threads to lookup these keys concurrently 3) create 2 threads to overwrite these keys concurrently
Without atomic update support, the lookup operation may return -ENOENT error and the test will fail. After the atomic-update change, the lookup operation will always return 0 and the test will succeed. Signed-off-by: Hou Tao <[email protected]> --- .../selftests/bpf/prog_tests/htab_lookup.c | 130 ++++++++++++++++++ .../testing/selftests/bpf/progs/htab_lookup.c | 13 ++ 2 files changed, 143 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/htab_lookup.c create mode 100644 tools/testing/selftests/bpf/progs/htab_lookup.c diff --git a/tools/testing/selftests/bpf/prog_tests/htab_lookup.c b/tools/testing/selftests/bpf/prog_tests/htab_lookup.c new file mode 100644 index 000000000000..ef9036827439 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/htab_lookup.c @@ -0,0 +1,130 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include <stdbool.h> +#include <test_progs.h> +#include "htab_lookup.skel.h" + +struct htab_op_ctx { + int fd; + int loop; + unsigned int entries; + bool stop; +}; + +static void *htab_lookup_fn(void *arg) +{ + struct htab_op_ctx *ctx = arg; + int i = 0; + + while (i++ < ctx->loop && !ctx->stop) { + unsigned int j; + + for (j = 0; j < ctx->entries; j++) { + unsigned long key = j, value; + int err; + + err = bpf_map_lookup_elem(ctx->fd, &key, &value); + if (err) { + ctx->stop = true; + return (void *)(long)err; + } + } + } + + return NULL; +} + +static void *htab_update_fn(void *arg) +{ + struct htab_op_ctx *ctx = arg; + int i = 0; + + while (i++ < ctx->loop && !ctx->stop) { + unsigned int j; + + for (j = 0; j < ctx->entries; j++) { + unsigned long key = j, value = j; + int err; + + err = bpf_map_update_elem(ctx->fd, &key, &value, BPF_EXIST); + if (err) { + if (err == -ENOMEM) + continue; + ctx->stop = true; + return (void *)(long)err; + } + } + } + + return NULL; +} + +static int setup_htab(int fd, unsigned int entries) +{ + unsigned int i; + + for (i = 0; i < entries; i++) { + unsigned long key = i, value = i; + int err; + + err = bpf_map_update_elem(fd, &key, &value, 0); + if (!ASSERT_OK(err, "init update")) + return -1; + } + + return 0; +} + +void test_htab_lookup(void) +{ + unsigned int i, wr_nr = 2, rd_nr = 8; + pthread_t tids[wr_nr + rd_nr]; + struct htab_lookup *skel; + struct htab_op_ctx ctx; + int err; + + skel = htab_lookup__open_and_load(); + if (!ASSERT_OK_PTR(skel, "htab_lookup__open_and_load")) + return; + + ctx.fd = bpf_map__fd(skel->maps.htab); + ctx.loop = 50; + ctx.stop = false; + ctx.entries = 64; + + err = setup_htab(ctx.fd, ctx.entries); + if (err) + goto destroy; + + memset(tids, 0, sizeof(tids)); + for (i = 0; i < wr_nr; i++) { + err = pthread_create(&tids[i], NULL, htab_update_fn, &ctx); + if (!ASSERT_OK(err, "pthread_create")) { + ctx.stop = true; + goto reap; + } + } + for (i = 0; i < rd_nr; i++) { + err = pthread_create(&tids[i + wr_nr], NULL, htab_lookup_fn, &ctx); + if (!ASSERT_OK(err, "pthread_create")) { + ctx.stop = true; + goto reap; + } + } + +reap: + for (i = 0; i < wr_nr + rd_nr; i++) { + void *ret = NULL; + char desc[32]; + + if (!tids[i]) + continue; + + snprintf(desc, sizeof(desc), "thread %u", i + 1); + err = pthread_join(tids[i], &ret); + ASSERT_OK(err, desc); + ASSERT_EQ(ret, NULL, desc); + } +destroy: + htab_lookup__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/htab_lookup.c b/tools/testing/selftests/bpf/progs/htab_lookup.c new file mode 100644 index 000000000000..baa30fa5b84f --- /dev/null +++ b/tools/testing/selftests/bpf/progs/htab_lookup.c @@ -0,0 +1,13 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/bpf.h> +#include <bpf/bpf_helpers.h> + +char _license[] SEC("license") = "GPL"; + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(max_entries, 64); + __type(key, unsigned long); + __type(value, unsigned long); + __uint(map_flags, BPF_F_NO_PREALLOC); +} htab SEC(".maps"); -- 2.48.1
