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Thomas Orgis" , Yiyang Chen Subject: [PATCH 2/2] selftests/acct: add cgroupstats functional test Date: Sat, 11 Jul 2026 04:07:37 +0800 Message-ID: <2a56921276f0962f97f00863e8c7d3c3f6893d5a.1783713230.git.cyyzero16@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add a self-contained test for the CGROUPSTATS_CMD_GET genl command that covers three cases: - querying a cgroup v1 hierarchy and verifying the response contains non-zero task counts - rejecting an invalid fd without NLM_F_ACK - rejecting an invalid fd with NLM_F_ACK Signed-off-by: Yiyang Chen --- tools/testing/selftests/acct/Makefile | 1 + tools/testing/selftests/acct/cgroupstats.c | 354 +++++++++++++++++++++ 2 files changed, 355 insertions(+) create mode 100644 tools/testing/selftests/acct/cgroupstats.c diff --git a/tools/testing/selftests/acct/Makefile b/tools/testing/selftests/acct/Makefile index 083cab5ddb72..db88d65f5581 100644 --- a/tools/testing/selftests/acct/Makefile +++ b/tools/testing/selftests/acct/Makefile @@ -1,6 +1,7 @@ # SPDX-License-Identifier: GPL-2.0 TEST_GEN_PROGS := acct_syscall TEST_GEN_PROGS += taskstats_fill_stats_tgid +TEST_GEN_PROGS += cgroupstats CFLAGS += -Wall LDLIBS += -lpthread diff --git a/tools/testing/selftests/acct/cgroupstats.c b/tools/testing/selftests/acct/cgroupstats.c new file mode 100644 index 000000000000..e2836383ed50 --- /dev/null +++ b/tools/testing/selftests/acct/cgroupstats.c @@ -0,0 +1,354 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#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 RECV_TIMEOUT_SEC 2 + +static void *nla_data(const struct nlattr *na) +{ + return (void *)((char *)na + NLA_HDRLEN); +} + +static int netlink_open(void) +{ + struct timeval tv = { .tv_sec = RECV_TIMEOUT_SEC }; + 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; + + /* + * Ensure that a missing kernel reply fails the individual test + * case instead of hanging the whole test binary. + */ + if (setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)) < 0) { + int err = -errno; + + close(fd); + return err; + } + + 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(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 (rem >= (int)sizeof(*na) && + na->nla_len >= (int)sizeof(*na) && + na->nla_len <= rem) { + if (na->nla_type == CTRL_ATTR_FAMILY_ID) + return *(uint16_t *)nla_data(na); + rem -= NLA_ALIGN(na->nla_len); + na = (struct nlattr *)((char *)na + NLA_ALIGN(na->nla_len)); + } + } + + return -ENOENT; +} + +static int send_cgroupstats_cmd(int fd, int family_id, uint32_t cgroup_fd, + int flags) +{ + struct { + struct nlmsghdr nlh; + struct genlmsghdr genl; + char buf[256]; + } req = { 0 }; + struct nlattr *na; + + req.nlh.nlmsg_len = NLMSG_LENGTH(GENL_HDRLEN); + req.nlh.nlmsg_type = family_id; + req.nlh.nlmsg_flags = NLM_F_REQUEST | flags; + req.nlh.nlmsg_seq = 2; + req.nlh.nlmsg_pid = getpid(); + + req.genl.cmd = CGROUPSTATS_CMD_GET; + req.genl.version = 1; + + na = (struct nlattr *)((char *)&req + NLMSG_ALIGN(req.nlh.nlmsg_len)); + na->nla_type = CGROUPSTATS_CMD_ATTR_FD; + na->nla_len = NLA_HDRLEN + sizeof(cgroup_fd); + memcpy(nla_data(na), &cgroup_fd, sizeof(cgroup_fd)); + req.nlh.nlmsg_len = NLMSG_ALIGN(req.nlh.nlmsg_len) + NLA_ALIGN(na->nla_len); + + return send_request(fd, &req, req.nlh.nlmsg_len); +} + +/* + * Receive and decode a cgroupstats response. + * + * Returns: + * 0 — success, stats filled from CGROUPSTATS_CMD_NEW reply + * <0 — NLMSG_ERROR errno (e.g. -EBADF, -EINVAL) + */ +static int recv_cgroupstats_response(int fd, struct cgroupstats *stats) +{ + char resp[8192]; + struct nlmsghdr *nlh; + struct genlmsghdr *genl; + struct nlattr *na; + int len; + int rem; + + memset(stats, 0, sizeof(*stats)); + + 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; + } + + genl = (struct genlmsghdr *)NLMSG_DATA(nlh); + if (genl->cmd != CGROUPSTATS_CMD_NEW) + continue; + + rem = nlh->nlmsg_len - NLMSG_HDRLEN - GENL_HDRLEN; + na = (struct nlattr *)((char *)genl + GENL_HDRLEN); + while (rem >= (int)sizeof(*na) && + na->nla_len >= (int)sizeof(*na) && + na->nla_len <= rem) { + if (na->nla_type == CGROUPSTATS_TYPE_CGROUP_STATS) { + memcpy(stats, nla_data(na), sizeof(*stats)); + return 0; + } + rem -= NLA_ALIGN(na->nla_len); + na = (struct nlattr *)((char *)na + NLA_ALIGN(na->nla_len)); + } + } + + return -EIO; +} + +/* mkdtemp() modifies the template in place, so this cannot be const. */ +static char cg_mountpoint[32]; +static bool cg_mounted; + +static int setup_cgroup_v1(void) +{ + strcpy(cg_mountpoint, "/tmp/cgstats_test_XXXXXX"); + + if (!mkdtemp(cg_mountpoint)) + return -errno; + + if (mount("cgstats_test", cg_mountpoint, "cgroup", 0, + "none,name=cgstats_test") < 0) { + int ret = -errno; + + rmdir(cg_mountpoint); + return ret; + } + + cg_mounted = true; + return 0; +} + +static void cleanup_cgroup_v1(void) +{ + if (!cg_mounted) + return; + umount2(cg_mountpoint, MNT_DETACH); + rmdir(cg_mountpoint); + cg_mounted = false; +} + +int main(void) +{ + struct cgroupstats stats; + uint64_t total_tasks; + int family_id; + int nl_fd; + int cg_fd; + int ret; + + ksft_print_header(); + + nl_fd = netlink_open(); + if (nl_fd < 0) + ksft_exit_skip("failed to open generic netlink socket: %s\n", + strerror(-nl_fd)); + + family_id = get_family_id(nl_fd, TASKSTATS_GENL_NAME); + if (family_id < 0) + ksft_exit_skip("taskstats generic netlink family unavailable: %s\n", + strerror(-family_id)); + + ksft_set_plan(3); + + /* + * Test 1: mount a private cgroup v1 hierarchy, query it, and + * verify the response contains sane task counts. If the test + * environment cannot create a private cgroup v1 mount, skip this + * case and continue with the unprivileged regression checks below. + */ + ret = setup_cgroup_v1(); + if (ret) { + ksft_test_result_skip("cgroupstats query: cannot mount cgroup v1: %s\n", + strerror(-ret)); + } else { + cg_fd = open(cg_mountpoint, O_RDONLY | O_DIRECTORY); + if (cg_fd < 0) { + ksft_test_result_fail("cgroupstats query: open mountpoint: %s\n", + strerror(errno)); + } else { + ret = send_cgroupstats_cmd(nl_fd, family_id, + (uint32_t)cg_fd, 0); + if (ret) { + ksft_test_result_fail("cgroupstats query: send: %s\n", + strerror(-ret)); + } else { + ret = recv_cgroupstats_response(nl_fd, &stats); + if (ret < 0) { + ksft_test_result_fail("cgroupstats query: %s\n", + strerror(-ret)); + } else { + total_tasks = (uint64_t)stats.nr_sleeping + + (uint64_t)stats.nr_running + + (uint64_t)stats.nr_stopped + + (uint64_t)stats.nr_uninterruptible + + (uint64_t)stats.nr_io_wait; + + ksft_print_msg("cgroupstats query: total_tasks=%llu\n", + (unsigned long long)total_tasks); + + ksft_test_result(total_tasks > 0, + "cgroupstats query returns valid stats\n"); + } + } + close(cg_fd); + } + } + cleanup_cgroup_v1(); + + /* + * Test 2: invalid fd without NLM_F_ACK. The kernel should + * return -EBADF via NLMSG_ERROR regardless of whether the + * client requested an explicit ACK. + */ + ret = send_cgroupstats_cmd(nl_fd, family_id, 0xFFFFFFFF, 0); + if (ret) + ksft_exit_fail_msg("send test 2 failed: %s\n", strerror(-ret)); + + ret = recv_cgroupstats_response(nl_fd, &stats); + ksft_print_msg("bad fd (no ACK): response=%d (%s)\n", + ret, ret < 0 ? strerror(-ret) : "unexpected success"); + ksft_test_result(ret == -EBADF, + "cgroupstats rejects bad fd without NLM_F_ACK\n"); + + /* + * Test 3: invalid fd with NLM_F_ACK. Same expectation as + * test 2, but exercised through a different netlink flag + * path in the kernel's ack/error handling. + */ + ret = send_cgroupstats_cmd(nl_fd, family_id, 0xFFFFFFFF, NLM_F_ACK); + if (ret) + ksft_exit_fail_msg("send test 3 failed: %s\n", strerror(-ret)); + + ret = recv_cgroupstats_response(nl_fd, &stats); + ksft_print_msg("bad fd (with ACK): response=%d (%s)\n", + ret, ret < 0 ? strerror(-ret) : "unexpected success"); + ksft_test_result(ret == -EBADF, + "cgroupstats rejects bad fd with NLM_F_ACK\n"); + + close(nl_fd); + ksft_finished(); + return ksft_get_fail_cnt() ? KSFT_FAIL : KSFT_PASS; +} -- 2.43.0