From patchwork Thu Apr 11 17:50:43 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 10896543 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4C249139A for ; Thu, 11 Apr 2019 17:51:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 347CB28D3E for ; Thu, 11 Apr 2019 17:51:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2812E28D64; Thu, 11 Apr 2019 17:51:09 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 59E0728D3E for ; Thu, 11 Apr 2019 17:51:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726633AbfDKRvH (ORCPT ); Thu, 11 Apr 2019 13:51:07 -0400 Received: from mail-pf1-f195.google.com ([209.85.210.195]:33942 "EHLO mail-pf1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726667AbfDKRvG (ORCPT ); Thu, 11 Apr 2019 13:51:06 -0400 Received: by mail-pf1-f195.google.com with SMTP id b3so3823261pfd.1 for ; Thu, 11 Apr 2019 10:51:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=1WrIR0QOrJAwS3O8qZx8u0RVTe8tfr2CaORBL+Co0xk=; b=uccv7bV+PZGraUVfb64/3l/Z98RLjyH4tb9mc9oMi5T53UkrcJMaLyW+6zVzEOSpOR KGtzqyO6v5QmmKrnOk8zD5bU2ucC0sYc+v6+MuLSjRox6qjDXb3hOdaGWF8BohTKgV88 q9UroqE3nKPUwL5MeJbnSBIDuw73IwaNN6CYE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=1WrIR0QOrJAwS3O8qZx8u0RVTe8tfr2CaORBL+Co0xk=; b=IQus6Qisj8PQUdzhXugbexYAbhiwx/UhKKzrs0eSr1aR7aJ1ISIgv4lfqEMu+gWXG/ GJKQaF1PgqjpUebznGyJhF4kEd1J2IOYcKmkFaMVQxVimKhGLx6HInh3XOqIj44NfGZ6 LXzQlMenEFyFqAHOveW1xAukZcf4tsF8u2WzwC4G63PsyE7rV4FS5Xt988dX6agC4aO8 Eie+4o1zv8yvbU+YYwCAaSayYzoZoRKZ6AAmbKtAsuZWXJL3HSQN80IB5j7tYqToXQzB hLsK4V0Dmvz8SVrMVTcJWqTUqW5NnYBYiRwpbBDmjsbdj7xkGtr1k2xAISQB3oM0C2X8 Viuw== X-Gm-Message-State: APjAAAWfKvPglu5LZ49mwhVeu/ltcKyM1gXMgxXrMz6R3Om8VYq93JF3 VVHpPXBlzWEtS5kj/M/e0QfxSg== X-Google-Smtp-Source: APXvYqyEBspSgCilT9XDbXPdxcIHARn2vp2dVZyccuVlh8ElwuJF902L52cribKxzCo9TRfaeh34Ig== X-Received: by 2002:a62:6490:: with SMTP id y138mr51320380pfb.230.1555005065044; Thu, 11 Apr 2019 10:51:05 -0700 (PDT) Received: from joelaf.cam.corp.google.com ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id d68sm58776474pfg.16.2019.04.11.10.51.01 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 11 Apr 2019 10:51:04 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org Cc: "Joel Fernandes (Google)" , Alexey Dobriyan , Al Viro , Andrei Vagin , Andrew Morton , Arnd Bergmann , Christian Brauner , dancol@google.com, "Eric W. Biederman" , jannh@google.com, Kees Cook , linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, luto@amacapital.net, Michal Hocko , Nadav Amit , Oleg Nesterov , rostedt@goodmis.org, Serge Hallyn , Shuah Khan , Stephen Rothwell , surenb@google.com, Taehee Yoo , Tejun Heo , Thomas Gleixner , torvalds@linux-foundation.org, Tycho Andersen Subject: [PATCH RFC 2/2] Add selftests for pidfd polling Date: Thu, 11 Apr 2019 13:50:43 -0400 Message-Id: <20190411175043.31207-2-joel@joelfernandes.org> X-Mailer: git-send-email 2.21.0.392.gf8f6787159e-goog In-Reply-To: <20190411175043.31207-1-joel@joelfernandes.org> References: <20190411175043.31207-1-joel@joelfernandes.org> MIME-Version: 1.0 Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Other than verifying pidfd based polling, the tests make sure that wait semantics are preserved with the pidfd poll. Notably the 2 cases: 1. If a thread group leader exits while threads still there, then no pidfd poll notifcation should happen. 2. If a non-thread group leader does an execve, then the thread group leader is signaled to exit and is replaced with the execing thread as the new leader, however the parent is not notified in this case. Signed-off-by: Joel Fernandes (Google) --- tools/testing/selftests/pidfd/Makefile | 2 +- tools/testing/selftests/pidfd/pidfd_test.c | 216 ++++++++++++++++++++- 2 files changed, 208 insertions(+), 10 deletions(-) diff --git a/tools/testing/selftests/pidfd/Makefile b/tools/testing/selftests/pidfd/Makefile index deaf8073bc06..4b31c14f273c 100644 --- a/tools/testing/selftests/pidfd/Makefile +++ b/tools/testing/selftests/pidfd/Makefile @@ -1,4 +1,4 @@ -CFLAGS += -g -I../../../../usr/include/ +CFLAGS += -g -I../../../../usr/include/ -lpthread TEST_GEN_PROGS := pidfd_test diff --git a/tools/testing/selftests/pidfd/pidfd_test.c b/tools/testing/selftests/pidfd/pidfd_test.c index d59378a93782..4d5206280091 100644 --- a/tools/testing/selftests/pidfd/pidfd_test.c +++ b/tools/testing/selftests/pidfd/pidfd_test.c @@ -4,18 +4,26 @@ #include #include #include +#include #include #include #include #include #include #include +#include +#include #include #include +#include #include #include "../kselftest.h" +#define CHILD_THREAD_MIN_WAIT 3 /* seconds */ +#define MAX_EVENTS 5 +#define __NR_pidfd_send_signal 424 + static inline int sys_pidfd_send_signal(int pidfd, int sig, siginfo_t *info, unsigned int flags) { @@ -30,6 +38,22 @@ static void set_signal_received_on_sigusr1(int sig) signal_received = 1; } +static int open_pidfd(const char *test_name, pid_t pid) +{ + char buf[256]; + int pidfd; + + snprintf(buf, sizeof(buf), "/proc/%d", pid); + pidfd = open(buf, O_DIRECTORY | O_CLOEXEC); + + if (pidfd < 0) + ksft_exit_fail_msg( + "%s test: Failed to open process file descriptor\n", + test_name); + + return pidfd; +} + /* * Straightforward test to see whether pidfd_send_signal() works is to send * a signal to ourself. @@ -87,7 +111,6 @@ static int wait_for_pid(pid_t pid) static int test_pidfd_send_signal_exited_fail(void) { int pidfd, ret, saved_errno; - char buf[256]; pid_t pid; const char *test_name = "pidfd_send_signal signal exited process"; @@ -99,17 +122,10 @@ static int test_pidfd_send_signal_exited_fail(void) if (pid == 0) _exit(EXIT_SUCCESS); - snprintf(buf, sizeof(buf), "/proc/%d", pid); - - pidfd = open(buf, O_DIRECTORY | O_CLOEXEC); + pidfd = open_pidfd(test_name, pid); (void)wait_for_pid(pid); - if (pidfd < 0) - ksft_exit_fail_msg( - "%s test: Failed to open process file descriptor\n", - test_name); - ret = sys_pidfd_send_signal(pidfd, 0, NULL, 0); saved_errno = errno; close(pidfd); @@ -368,10 +384,192 @@ static int test_pidfd_send_signal_syscall_support(void) return 0; } +void *test_pidfd_poll_exec_thread(void *priv) +{ + char waittime[256]; + + ksft_print_msg("Child Thread: starting. pid %d tid %d ; and sleeping\n", + getpid(), syscall(SYS_gettid)); + ksft_print_msg("Child Thread: doing exec of sleep\n"); + + sprintf(waittime, "%d", CHILD_THREAD_MIN_WAIT); + execl("/bin/sleep", "sleep", waittime, (char *)NULL); + + ksft_print_msg("Child Thread: DONE. pid %d tid %d\n", + getpid(), syscall(SYS_gettid)); + return NULL; +} + +static int poll_pidfd(const char *test_name, int pidfd) +{ + int c; + int epoll_fd = epoll_create1(0); + struct epoll_event event, events[MAX_EVENTS]; + + if (epoll_fd == -1) + ksft_exit_fail_msg("%s test: Failed to create epoll file descriptor\n", + test_name); + + event.events = EPOLLIN; + event.data.fd = pidfd; + + if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, pidfd, &event)) { + ksft_print_msg("%s test: Failed to add epoll file descriptor: Skipping\n", + test_name); + _exit(PIDFD_SKIP); + } + + c = epoll_wait(epoll_fd, events, MAX_EVENTS, 5000); + if (c != 1 || !(events[0].events & EPOLLIN)) + ksft_exit_fail_msg("%s test: Unexpected epoll_wait result (c=%d, events=%x)\n", + test_name, c, events[0].events); + + close(epoll_fd); + return events[0].events; + +} + +int test_pidfd_poll_exec(int use_waitpid) +{ + int pid, pidfd; + int status, ret; + pthread_t t1; + time_t prog_start = time(NULL); + const char *test_name = "pidfd_poll check for premature notification on child thread exec"; + + ksft_print_msg("Parent: pid: %d\n", getpid()); + pid = fork(); + if (pid == 0) { + ksft_print_msg("Child: starting. pid %d tid %d\n", getpid(), + syscall(SYS_gettid)); + pthread_create(&t1, NULL, test_pidfd_poll_exec_thread, NULL); + /* + * Exec in the non-leader thread will destroy the leader immediately. + * If the wait in the parent returns too soon, the test fails. + */ + while (1) + ; + } + + ksft_print_msg("Parent: Waiting for Child (%d) to complete.\n", pid); + + if (use_waitpid) { + ret = waitpid(pid, &status, 0); + if (ret == -1) + ksft_print_msg("Parent: error\n"); + + if (ret == pid) + ksft_print_msg("Parent: Child process waited for.\n"); + } else { + pidfd = open_pidfd(test_name, pid); + if (poll_pidfd(test_name, pidfd) & EPOLLERR) + ksft_exit_fail_msg("%s test: Unexpected epoll error\n", test_name); + } + + time_t prog_time = time(NULL) - prog_start; + + ksft_print_msg("Time waited for child: %lu\n", prog_time); + + /* Check to make sure poll_pidfd returns error after reaping */ + if (!use_waitpid && + (waitpid(pid, &status, 0) != pid || !(poll_pidfd(test_name, pidfd) & EPOLLERR))) { + ksft_exit_fail_msg("%s test: poll_pidfd EPOLLERR check failed\n", test_name); + } + close(pidfd); + + if (prog_time < CHILD_THREAD_MIN_WAIT || prog_time > CHILD_THREAD_MIN_WAIT + 2) + ksft_exit_fail_msg("%s test: Failed\n", test_name); + else + ksft_test_result_pass("%s test: Passed\n", test_name); +} + +void *test_pidfd_poll_leader_exit_thread(void *priv) +{ + char waittime[256]; + + ksft_print_msg("Child Thread: starting. pid %d tid %d ; and sleeping\n", + getpid(), syscall(SYS_gettid)); + sleep(CHILD_THREAD_MIN_WAIT); + ksft_print_msg("Child Thread: DONE. pid %d tid %d\n", getpid(), syscall(SYS_gettid)); + return NULL; +} + +static time_t *child_exit_secs; +int test_pidfd_poll_leader_exit(int use_waitpid) +{ + int pid, pidfd; + int status, ret; + pthread_t t1, t2; + time_t prog_start = time(NULL); + const char *test_name = "pidfd_poll check for premature notification on non-empty" + "group leader exit"; + + child_exit_secs = mmap(NULL, sizeof *child_exit_secs, PROT_READ | PROT_WRITE, + MAP_SHARED | MAP_ANONYMOUS, -1, 0); + + ksft_print_msg("Parent: pid: %d\n", getpid()); + pid = fork(); + if (pid == 0) { + ksft_print_msg("Child: starting. pid %d tid %d\n", getpid(), syscall(SYS_gettid)); + pthread_create(&t1, NULL, test_pidfd_poll_leader_exit_thread, NULL); + pthread_create(&t2, NULL, test_pidfd_poll_leader_exit_thread, NULL); + + /* + * glibc exit calls exit_group syscall, so explicity call exit only + * so that only the group leader exits, leaving the threads alone. + */ + *child_exit_secs = time(NULL); + syscall(SYS_exit, 0); + } + + ksft_print_msg("Parent: Waiting for Child (%d) to complete.\n", pid); + + if (use_waitpid) { + ret = waitpid(pid, &status, 0); + if (ret == -1) + ksft_print_msg("Parent: error\n"); + } else { + /* + * This sleep tests for the case where if the child exits, and is in + * EXIT_ZOMBIE, but the thread group leader is non-empty, then the poll + * doesn't prematurely return even though there are active threads + */ + sleep(1); + pidfd = open_pidfd(test_name, pid); + if (poll_pidfd(test_name, pidfd) & EPOLLERR) + ksft_exit_fail_msg("%s test: Unexpected epoll error\n", test_name); + } + + if (ret == pid) + ksft_print_msg("Parent: Child process waited for.\n"); + + time_t since_child_exit = time(NULL) - *child_exit_secs; + + ksft_print_msg("Time since child exit: %lu\n", since_child_exit); + + /* Check to make sure poll_pidfd returns error after reaping */ + if (!use_waitpid && + (waitpid(pid, &status, 0) != pid || + !(poll_pidfd(test_name, pidfd) & EPOLLERR))) { + ksft_exit_fail_msg("%s test: poll_pidfd EPOLLERR check failed\n", test_name); + } + close(pidfd); + + if (since_child_exit < CHILD_THREAD_MIN_WAIT || + since_child_exit > CHILD_THREAD_MIN_WAIT + 2) + ksft_exit_fail_msg("%s test: Failed\n", test_name); + else + ksft_test_result_pass("%s test: Passed\n", test_name); +} + int main(int argc, char **argv) { ksft_print_header(); + test_pidfd_poll_exec(0); + test_pidfd_poll_exec(1); + test_pidfd_poll_leader_exit(0); + test_pidfd_poll_leader_exit(1); test_pidfd_send_signal_syscall_support(); test_pidfd_send_signal_simple_success(); test_pidfd_send_signal_exited_fail();