From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 49046C10F0E for ; Fri, 12 Apr 2019 14:51:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 016DA20850 for ; Fri, 12 Apr 2019 14:51:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=tycho-ws.20150623.gappssmtp.com header.i=@tycho-ws.20150623.gappssmtp.com header.b="KDCoIiuX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726825AbfDLOvO (ORCPT ); Fri, 12 Apr 2019 10:51:14 -0400 Received: from mail-pl1-f193.google.com ([209.85.214.193]:40396 "EHLO mail-pl1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726768AbfDLOvO (ORCPT ); Fri, 12 Apr 2019 10:51:14 -0400 Received: by mail-pl1-f193.google.com with SMTP id b3so5249641plr.7 for ; Fri, 12 Apr 2019 07:51:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tycho-ws.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=gJ7mrR0FJdKtUm9hgWTgDFwxTZouCV5ViaCav1iI6lw=; b=KDCoIiuXP1IvzM3NacxtCzJt5ZAtaKyVT97VuqiihxJDQz2yaKpZp0nU5IVvVno2Ge F2oQvaYFCkoufVWHbKVSj59niFP4Ol4N8LinsR8r1J/G+LgQMUM0xVBV3EHcm5AmJNk0 BBOb88ErqUzhhs4RLPSrOX2zFvuj4jIYWN4t9P4EcAl0p13UJSSUl1yCmZ8dtkvJaon7 Ec+JgCa6jZMDh/R4mJwPLwlCiJ8a1Hsp03NHOmQbdVSiGU+sXwEeLcByDMjKkOztUfDW d5MR6wq9KMdIgW1OPKoSUv0ux3En/QFbMOyo/wQy0DRvIeLUIM3eD/SxZ90GNszHDYZZ E8fQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=gJ7mrR0FJdKtUm9hgWTgDFwxTZouCV5ViaCav1iI6lw=; b=PH+vHYWfkdyvS4JbGHjWw2MmI3PTAXDNL4sIhco4zA4IfhAj1heIMtUdZ+ys/qDBOr n1ERUBvK6m58drtp59tky19mDkq8L/4GJwAJ9HVd7SsVqK89ht6sUKJOhoe/kEkSQi0D jGMcq+Nmz1rVr7ypv4QDwSUu2OzgREfuMDSAAoTUqZ6QKkVbRE6v6LkaJXO6Feg2H6nk fm0QvLhpqre68ujMeMx7M0EctWLsvyhiu/YyGYmkWlByycovzN8oxV8JOo0cl0GIVc4Y 5iddKkQ8WjwLSaxNsfr/nWqjaTv6J0VHs+x8bRU3RrhFkKQW5rKeH7NUdnJ/G7ziIy/N umRw== X-Gm-Message-State: APjAAAWF36bp9K0GtnKwEqHdUqUHVIVwr+aRj7q8W9/hbHeCYQuecoXn Lf2AmF6/E11PFNmNte/2yMMaBA== X-Google-Smtp-Source: APXvYqzhq94ZLZfVJPG/qnZ9qdHh4IlI9yoQJ7PIKRsZA4a0llF8szDW1zzgirgf2HLDIbTJVaF1zw== X-Received: by 2002:a17:902:70c8:: with SMTP id l8mr58303624plt.177.1555080672815; Fri, 12 Apr 2019 07:51:12 -0700 (PDT) Received: from cisco ([2601:282:901:dd7b:e0a2:3243:c21a:e844]) by smtp.gmail.com with ESMTPSA id p7sm76120189pfp.70.2019.04.12.07.51.10 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 12 Apr 2019 07:51:12 -0700 (PDT) Date: Fri, 12 Apr 2019 08:51:09 -0600 From: Tycho Andersen To: "Joel Fernandes (Google)" Cc: linux-kernel@vger.kernel.org, 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 Subject: Re: [PATCH RFC 2/2] Add selftests for pidfd polling Message-ID: <20190412145109.GA25793@cisco> References: <20190411175043.31207-1-joel@joelfernandes.org> <20190411175043.31207-2-joel@joelfernandes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190411175043.31207-2-joel@joelfernandes.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, Apr 11, 2019 at 01:50:43PM -0400, Joel Fernandes (Google) wrote: > 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) I think you can do static here? > +{ > + 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)); You execl(), but then print stuff after that? Might also be worth switching to execlp(). > + return NULL; > +} > + > +static int poll_pidfd(const char *test_name, int pidfd) > +{ > + int c; > + int epoll_fd = epoll_create1(0); A style point, but I find it's best not to do resource allocation in variable declarations like this. It breaks up the usual pattern of: ret = -ENOMEM; resource = allocate(); if (allocation_failed(resource)) goto err; ... out: free(resource); err: return ret; You're not closing this fd on every path (they all exit [for now :D] so it's probably ok), but it might be nice to make this match a more regular pattern. > + 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); Might be worth checking errno == EPERM here too (which according to the man page is the error for "epoll not supported", which is weird :). > + _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) I think this can be static too. > +{ > + 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) Another static I think? Tycho