--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+
+#include <errno.h>
+#include <linux/genetlink.h>
+#include <linux/netlink.h>
+#include <linux/taskstats.h>
+#include <pthread.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "kselftest.h"
+
+#ifndef NLA_ALIGN
+#define NLA_ALIGNTO 4
+#define NLA_ALIGN(len) (((len) + NLA_ALIGNTO - 1) & ~(NLA_ALIGNTO - 1))
+#define NLA_HDRLEN ((int)NLA_ALIGN(sizeof(struct nlattr)))
+#endif
+
+#define BUSY_NS (200ULL * 1000 * 1000)
+
+struct worker_ctx {
+ pthread_mutex_t lock;
+ pthread_cond_t cond;
+ bool ready;
+ bool release;
+};
+
+static unsigned long busy_sink;
+
+static void *taskstats_nla_data(const struct nlattr *na)
+{
+ return (void *)((char *)na + NLA_HDRLEN);
+}
+
+static bool taskstats_nla_ok(const struct nlattr *na, int remaining)
+{
+ return remaining >= (int)sizeof(*na) &&
+ na->nla_len >= sizeof(*na) &&
+ na->nla_len <= remaining;
+}
+
+static struct nlattr *taskstats_nla_next(const struct nlattr *na, int *remaining)
+{
+ int aligned_len = NLA_ALIGN(na->nla_len);
+
+ *remaining -= aligned_len;
+ return (struct nlattr *)((char *)na + aligned_len);
+}
+
+static uint64_t timespec_diff_ns(const struct timespec *start,
+ const struct timespec *end)
+{
+ return (uint64_t)(end->tv_sec - start->tv_sec) * 1000000000ULL +
+ (uint64_t)(end->tv_nsec - start->tv_nsec);
+}
+
+static void burn_cpu_for_ns(uint64_t runtime_ns)
+{
+ struct timespec start, now;
+ unsigned long acc = 0;
+
+ if (clock_gettime(CLOCK_MONOTONIC, &start)) {
+ perror("clock_gettime");
+ exit(EXIT_FAILURE);
+ }
+
+ do {
+ for (int i = 0; i < 100000; i++)
+ acc += i;
+ if (clock_gettime(CLOCK_MONOTONIC, &now)) {
+ perror("clock_gettime");
+ exit(EXIT_FAILURE);
+ }
+ } while (timespec_diff_ns(&start, &now) < runtime_ns);
+
+ busy_sink = acc;
+}
+
+static int netlink_open(void)
+{
+ struct sockaddr_nl addr = {
+ .nl_family = AF_NETLINK,
+ .nl_pid = getpid(),
+ };
+ int fd;
+
+ fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
+ if (fd < 0)
+ return -errno;
+
+ if (bind(fd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
+ int err = -errno;
+
+ close(fd);
+ return err;
+ }
+
+ return fd;
+}
+
+static int send_request(int fd, void *buf, size_t len)
+{
+ struct sockaddr_nl addr = {
+ .nl_family = AF_NETLINK,
+ };
+
+ if (sendto(fd, buf, len, 0, (struct sockaddr *)&addr, sizeof(addr)) < 0)
+ return -errno;
+
+ return 0;
+}
+
+static int get_family_id(int fd, const char *name)
+{
+ struct {
+ struct nlmsghdr nlh;
+ struct genlmsghdr genl;
+ char buf[256];
+ } req = { 0 };
+ char resp[8192];
+ struct nlmsghdr *nlh;
+ struct genlmsghdr *genl;
+ struct nlattr *na;
+ int len;
+ int rem;
+ int ret;
+
+ req.nlh.nlmsg_len = NLMSG_LENGTH(GENL_HDRLEN);
+ req.nlh.nlmsg_type = GENL_ID_CTRL;
+ req.nlh.nlmsg_flags = NLM_F_REQUEST;
+ req.nlh.nlmsg_seq = 1;
+ req.nlh.nlmsg_pid = getpid();
+
+ req.genl.cmd = CTRL_CMD_GETFAMILY;
+ req.genl.version = 1;
+
+ na = (struct nlattr *)((char *)&req + NLMSG_ALIGN(req.nlh.nlmsg_len));
+ na->nla_type = CTRL_ATTR_FAMILY_NAME;
+ na->nla_len = NLA_HDRLEN + strlen(name) + 1;
+ memcpy(taskstats_nla_data(na), name, strlen(name) + 1);
+ req.nlh.nlmsg_len = NLMSG_ALIGN(req.nlh.nlmsg_len) + NLA_ALIGN(na->nla_len);
+
+ ret = send_request(fd, &req, req.nlh.nlmsg_len);
+ if (ret)
+ return ret;
+
+ len = recv(fd, resp, sizeof(resp), 0);
+ if (len < 0)
+ return -errno;
+
+ for (nlh = (struct nlmsghdr *)resp; NLMSG_OK(nlh, len);
+ nlh = NLMSG_NEXT(nlh, len)) {
+ if (nlh->nlmsg_type == NLMSG_ERROR) {
+ struct nlmsgerr *err = NLMSG_DATA(nlh);
+
+ return err->error ? err->error : -ENOENT;
+ }
+
+ genl = (struct genlmsghdr *)NLMSG_DATA(nlh);
+ rem = nlh->nlmsg_len - NLMSG_HDRLEN - GENL_HDRLEN;
+ na = (struct nlattr *)((char *)genl + GENL_HDRLEN);
+ while (taskstats_nla_ok(na, rem)) {
+ if (na->nla_type == CTRL_ATTR_FAMILY_ID)
+ return *(uint16_t *)taskstats_nla_data(na);
+ na = taskstats_nla_next(na, &rem);
+ }
+ }
+
+ return -ENOENT;
+}
+
+static int get_taskstats(int fd, int family_id, uint16_t attr_type, uint32_t id,
+ struct taskstats *stats)
+{
+ struct {
+ struct nlmsghdr nlh;
+ struct genlmsghdr genl;
+ char buf[256];
+ } req = { 0 };
+ char resp[16384];
+ struct nlmsghdr *nlh;
+ struct genlmsghdr *genl;
+ struct nlattr *na;
+ struct nlattr *nested;
+ int len;
+ int rem;
+ int nrem;
+ int ret;
+
+ memset(stats, 0, sizeof(*stats));
+
+ req.nlh.nlmsg_len = NLMSG_LENGTH(GENL_HDRLEN);
+ req.nlh.nlmsg_type = family_id;
+ req.nlh.nlmsg_flags = NLM_F_REQUEST;
+ req.nlh.nlmsg_seq = 2;
+ req.nlh.nlmsg_pid = getpid();
+
+ req.genl.cmd = TASKSTATS_CMD_GET;
+ req.genl.version = 1;
+
+ na = (struct nlattr *)((char *)&req + NLMSG_ALIGN(req.nlh.nlmsg_len));
+ na->nla_type = attr_type;
+ na->nla_len = NLA_HDRLEN + sizeof(id);
+ memcpy(taskstats_nla_data(na), &id, sizeof(id));
+ req.nlh.nlmsg_len = NLMSG_ALIGN(req.nlh.nlmsg_len) + NLA_ALIGN(na->nla_len);
+
+ ret = send_request(fd, &req, req.nlh.nlmsg_len);
+ if (ret)
+ return ret;
+
+ len = recv(fd, resp, sizeof(resp), 0);
+ if (len < 0)
+ return -errno;
+
+ for (nlh = (struct nlmsghdr *)resp; NLMSG_OK(nlh, len);
+ nlh = NLMSG_NEXT(nlh, len)) {
+ if (nlh->nlmsg_type == NLMSG_ERROR) {
+ struct nlmsgerr *err = NLMSG_DATA(nlh);
+
+ return err->error ? err->error : -ENOENT;
+ }
+
+ genl = (struct genlmsghdr *)NLMSG_DATA(nlh);
+ rem = nlh->nlmsg_len - NLMSG_HDRLEN - GENL_HDRLEN;
+ na = (struct nlattr *)((char *)genl + GENL_HDRLEN);
+ while (taskstats_nla_ok(na, rem)) {
+ if (na->nla_type == TASKSTATS_TYPE_AGGR_PID ||
+ na->nla_type == TASKSTATS_TYPE_AGGR_TGID) {
+ nested = (struct nlattr *)taskstats_nla_data(na);
+ nrem = na->nla_len - NLA_HDRLEN;
+ while (taskstats_nla_ok(nested, nrem)) {
+ if (nested->nla_type == TASKSTATS_TYPE_STATS) {
+ memcpy(stats, taskstats_nla_data(nested),
+ sizeof(*stats));
+ return 0;
+ }
+ nested = taskstats_nla_next(nested, &nrem);
+ }
+ }
+ na = taskstats_nla_next(na, &rem);
+ }
+ }
+
+ return -ENOENT;
+}
+
+static uint64_t cpu_total(const struct taskstats *stats)
+{
+ return (uint64_t)stats->ac_utime + (uint64_t)stats->ac_stime;
+}
+
+static void print_stats(const char *label, const struct taskstats *stats)
+{
+ ksft_print_msg("%s: cpu_total=%llu nvcsw=%llu nivcsw=%llu\n",
+ label, (unsigned long long)cpu_total(stats),
+ (unsigned long long)stats->nvcsw,
+ (unsigned long long)stats->nivcsw);
+}
+
+static void *worker_thread(void *arg)
+{
+ struct worker_ctx *ctx = arg;
+
+ burn_cpu_for_ns(BUSY_NS);
+
+ pthread_mutex_lock(&ctx->lock);
+ ctx->ready = true;
+ pthread_cond_broadcast(&ctx->cond);
+ while (!ctx->release)
+ pthread_cond_wait(&ctx->cond, &ctx->lock);
+ pthread_mutex_unlock(&ctx->lock);
+
+ return NULL;
+}
+
+int main(void)
+{
+ struct worker_ctx ctx = {
+ .lock = PTHREAD_MUTEX_INITIALIZER,
+ .cond = PTHREAD_COND_INITIALIZER,
+ };
+ struct taskstats before, after;
+ pthread_t thread;
+ pid_t tgid = getpid();
+ int family_id;
+ int fd;
+ int ret;
+
+ ksft_print_header();
+ ksft_set_plan(1);
+
+ if (geteuid())
+ ksft_exit_skip("taskstats_fill_stats_tgid needs root\n");
+
+ fd = netlink_open();
+ if (fd < 0)
+ ksft_exit_skip("failed to open generic netlink socket: %s\n",
+ strerror(-fd));
+
+ family_id = get_family_id(fd, TASKSTATS_GENL_NAME);
+ if (family_id < 0)
+ ksft_exit_skip("taskstats generic netlink family unavailable: %s\n",
+ strerror(-family_id));
+
+ /* Create worker thread that burns 200ms of CPU */
+ if (pthread_create(&thread, NULL, worker_thread, &ctx) != 0)
+ ksft_exit_fail_msg("pthread_create failed: %s\n", strerror(errno));
+
+ /* Wait for worker to finish generating activity */
+ pthread_mutex_lock(&ctx.lock);
+ while (!ctx.ready)
+ pthread_cond_wait(&ctx.cond, &ctx.lock);
+ pthread_mutex_unlock(&ctx.lock);
+
+ /*
+ * Snapshot A: TGID stats while worker is alive and sleeping.
+ * Contains main thread + worker contributions.
+ */
+ ret = get_taskstats(fd, family_id, TASKSTATS_CMD_ATTR_TGID, tgid, &before);
+ if (ret)
+ ksft_exit_fail_msg("TGID query before exit failed: %s\n",
+ strerror(-ret));
+
+ /* Release worker so it can exit, then join (deterministic wait).
+ *
+ * Kernel exit path ordering guarantees:
+ * do_exit()
+ * taskstats_exit() -> fill_tgid_exit() (accumulates worker into signal->stats)
+ * exit_notify() (releases the thread)
+ * do_task_dead() -> __schedule() (wakes joiner)
+ *
+ * So pthread_join() returns only after fill_tgid_exit() has completed.
+ */
+ pthread_mutex_lock(&ctx.lock);
+ ctx.release = true;
+ pthread_cond_broadcast(&ctx.cond);
+ pthread_mutex_unlock(&ctx.lock);
+
+ pthread_join(thread, NULL);
+
+ /*
+ * Snapshot B: TGID stats after worker has exited.
+ * fill_stats_for_tgid() does:
+ * memcpy(signal->stats) <- includes fill_tgid_exit accumulation
+ * + scan live threads <- only main thread now
+ */
+ ret = get_taskstats(fd, family_id, TASKSTATS_CMD_ATTR_TGID, tgid, &after);
+ if (ret)
+ ksft_exit_fail_msg("TGID query after exit failed: %s\n",
+ strerror(-ret));
+
+ print_stats("TGID before worker exit", &before);
+ print_stats("TGID after worker exit", &after);
+
+ /*
+ * The worker burned 200ms of CPU before the first snapshot.
+ * If the kernel correctly retained its contribution via
+ * fill_tgid_exit(), then the TGID CPU total after exit must be at
+ * least as large as the TGID CPU total before exit.
+ */
+ ksft_test_result(cpu_total(&after) >= cpu_total(&before),
+ "TGID CPU stats should not regress after thread exit\n");
+
+ close(fd);
+ ksft_finished();
+ return ksft_get_fail_cnt() ? KSFT_FAIL : KSFT_PASS;
+}
projects / thirdparty / linux.git / commitdiff
