From patchwork Wed Sep 2 10:21:27 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 11750255 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9FDAB1709 for ; Wed, 2 Sep 2020 10:23:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8E22A20BED for ; Wed, 2 Sep 2020 10:23:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726285AbgIBKXV (ORCPT ); Wed, 2 Sep 2020 06:23:21 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:49490 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726177AbgIBKXU (ORCPT ); Wed, 2 Sep 2020 06:23:20 -0400 Received: from ip5f5af70b.dynamic.kabel-deutschland.de ([95.90.247.11] helo=wittgenstein.fritz.box) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1kDPvC-00069F-5z; Wed, 02 Sep 2020 10:23:18 +0000 From: Christian Brauner To: linux-kernel@vger.kernel.org Cc: Christian Brauner , "Peter Zijlstra (Intel)" , Ingo Molnar , Thomas Gleixner , Oleg Nesterov , "Eric W. Biederman" , Kees Cook , Sargun Dhillon , Aleksa Sarai , linux-kselftest@vger.kernel.org, Josh Triplett , Jens Axboe , linux-api@vger.kernel.org, Christian Brauner Subject: [PATCH v2 1/4] pidfd: support PIDFD_NONBLOCK in pidfd_open() Date: Wed, 2 Sep 2020 12:21:27 +0200 Message-Id: <20200902102130.147672-2-christian.brauner@ubuntu.com> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200902102130.147672-1-christian.brauner@ubuntu.com> References: <20200902102130.147672-1-christian.brauner@ubuntu.com> MIME-Version: 1.0 Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Introduce PIDFD_NONBLOCK to support non-blocking pidfd file descriptors. Ever since the introduction of pidfds and more advanced async io various programming languages such as Rust have grown support for async event libraries. These libraries are created to help build epoll-based event loops around file descriptors. A common pattern is to automatically make all file descriptors they manage to O_NONBLOCK. For such libraries the EAGAIN error code is treated specially. When a function is called that returns EAGAIN the function isn't called again until the event loop indicates the the file descriptor is ready. Supporting EAGAIN when waiting on pidfds makes such libraries just work with little effort. In the following patch we will extend waitid() internally to support non-blocking pidfds. This introduces a new flag PIDFD_NONBLOCK that is equivalent to O_NONBLOCK. This follows the same patterns we have for other (anon inode) file descriptors such as EFD_NONBLOCK, IN_NONBLOCK, SFD_NONBLOCK, TFD_NONBLOCK and the same for close-on-exec flags. Link: https://lore.kernel.org/lkml/20200811181236.GA18763@localhost/ Link: https://github.com/joshtriplett/async-pidfd Cc: Kees Cook Cc: Sargun Dhillon Cc: Oleg Nesterov Suggested-by: Josh Triplett Signed-off-by: Christian Brauner Reviewed-by: Oleg Nesterov Reviewed-by: Josh Triplett --- /* v2 */ - Christian Brauner : - Improve commit message. --- include/uapi/linux/pidfd.h | 12 ++++++++++++ kernel/pid.c | 12 +++++++----- 2 files changed, 19 insertions(+), 5 deletions(-) create mode 100644 include/uapi/linux/pidfd.h diff --git a/include/uapi/linux/pidfd.h b/include/uapi/linux/pidfd.h new file mode 100644 index 000000000000..5406fbc13074 --- /dev/null +++ b/include/uapi/linux/pidfd.h @@ -0,0 +1,12 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ + +#ifndef _UAPI_LINUX_PIDFD_H +#define _UAPI_LINUX_PIDFD_H + +#include +#include + +/* Flags for pidfd_open(). */ +#define PIDFD_NONBLOCK O_NONBLOCK + +#endif /* _UAPI_LINUX_PIDFD_H */ diff --git a/kernel/pid.c b/kernel/pid.c index b2562a7ce525..74ddbff1a6ba 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -43,6 +43,7 @@ #include #include #include +#include struct pid init_struct_pid = { .count = REFCOUNT_INIT(1), @@ -522,7 +523,8 @@ struct pid *find_ge_pid(int nr, struct pid_namespace *ns) /** * pidfd_create() - Create a new pid file descriptor. * - * @pid: struct pid that the pidfd will reference + * @pid: struct pid that the pidfd will reference + * @flags: flags to pass * * This creates a new pid file descriptor with the O_CLOEXEC flag set. * @@ -532,12 +534,12 @@ struct pid *find_ge_pid(int nr, struct pid_namespace *ns) * Return: On success, a cloexec pidfd is returned. * On error, a negative errno number will be returned. */ -static int pidfd_create(struct pid *pid) +static int pidfd_create(struct pid *pid, unsigned int flags) { int fd; fd = anon_inode_getfd("[pidfd]", &pidfd_fops, get_pid(pid), - O_RDWR | O_CLOEXEC); + flags | O_RDWR | O_CLOEXEC); if (fd < 0) put_pid(pid); @@ -565,7 +567,7 @@ SYSCALL_DEFINE2(pidfd_open, pid_t, pid, unsigned int, flags) int fd; struct pid *p; - if (flags) + if (flags & ~PIDFD_NONBLOCK) return -EINVAL; if (pid <= 0) @@ -576,7 +578,7 @@ SYSCALL_DEFINE2(pidfd_open, pid_t, pid, unsigned int, flags) return -ESRCH; if (pid_has_task(p, PIDTYPE_TGID)) - fd = pidfd_create(p); + fd = pidfd_create(p, flags); else fd = -EINVAL; From patchwork Wed Sep 2 10:21:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 11750259 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 72E561575 for ; Wed, 2 Sep 2020 10:23:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6585A208DB for ; Wed, 2 Sep 2020 10:23:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726377AbgIBKXY (ORCPT ); Wed, 2 Sep 2020 06:23:24 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:49494 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726210AbgIBKXV (ORCPT ); Wed, 2 Sep 2020 06:23:21 -0400 Received: from ip5f5af70b.dynamic.kabel-deutschland.de ([95.90.247.11] helo=wittgenstein.fritz.box) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1kDPvC-00069F-UV; Wed, 02 Sep 2020 10:23:19 +0000 From: Christian Brauner To: linux-kernel@vger.kernel.org Cc: Christian Brauner , "Peter Zijlstra (Intel)" , Ingo Molnar , Thomas Gleixner , Oleg Nesterov , "Eric W. Biederman" , Kees Cook , Sargun Dhillon , Aleksa Sarai , linux-kselftest@vger.kernel.org, Josh Triplett , Jens Axboe , linux-api@vger.kernel.org, Christian Brauner , Jann Horn Subject: [PATCH v2 2/4] exit: support non-blocking pidfds Date: Wed, 2 Sep 2020 12:21:28 +0200 Message-Id: <20200902102130.147672-3-christian.brauner@ubuntu.com> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200902102130.147672-1-christian.brauner@ubuntu.com> References: <20200902102130.147672-1-christian.brauner@ubuntu.com> MIME-Version: 1.0 Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Passing a non-blocking pidfd to waitid() currently has no effect, i.e. is not supported. There are users which would like to use waitid() on pidfds that are O_NONBLOCK and mix it with pidfds that are blocking and both pass them to waitid(). The expected behavior is to have waitid() return -EAGAIN for non-blocking pidfds and to block for blocking pidfds without needing to perform any additional checks for flags set on the pidfd before passing it to waitid(). Non-blocking pidfds will return EAGAIN from waitid() when no child process is ready yet. Returning -EAGAIN for non-blocking pidfds makes it easier for event loops that handle EAGAIN specially. It also makes the API more consistent and uniform. In essence, waitid() is treated like a read on a non-blocking pidfd or a recvmsg() on a non-blocking socket. With the addition of support for non-blocking pidfds we support the same functionality that sockets do. For sockets() recvmsg() supports MSG_DONTWAIT for pidfds waitid() supports WNOHANG. Both flags are per-call options. In contrast non-blocking pidfds and non-blocking sockets are a setting on an open file description affecting all threads in the calling process as well as other processes that hold file descriptors referring to the same open file description. Both behaviors, per call and per open file description, have genuine use-cases. The implementation should be straightforward, we simply raise the WNOHANG flag when a non-blocking pidfd is passed and when do_wait() returns without finding an eligible task and the pidfd is non-blocking we set EAGAIN. If no child process exists non-blocking pidfd users will continue to see ECHILD but if child processes exist but have not yet exited users will see EAGAIN. A concrete use-case that was brought on-list was Josh's async pidfd library. Ever since the introduction of pidfds and more advanced async io various programming languages such as Rust have grown support for async event libraries. These libraries are created to help build epoll-based event loops around file descriptors. A common pattern is to automatically make all file descriptors they manage to O_NONBLOCK. For such libraries the EAGAIN error code is treated specially. When a function is called that returns EAGAIN the function isn't called again until the event loop indicates the the file descriptor is ready. Supporting EAGAIN when waiting on pidfds makes such libraries just work with little effort. Link: https://lore.kernel.org/lkml/20200811181236.GA18763@localhost/ Link: https://github.com/joshtriplett/async-pidfd Cc: Kees Cook Cc: Sargun Dhillon Cc: Jann Horn Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Oleg Nesterov Cc: "Peter Zijlstra (Intel)" Suggested-by: Josh Triplett Signed-off-by: Christian Brauner Reviewed-by: Oleg Nesterov Reviewed-by: Josh Triplett --- /* v2 */ - Oleg Nesterov : - Remove the eagain_error and simple set to EAGAIN in kernel_waitid() if pidfd is non-blocking and no child process has yet exited. --- kernel/exit.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index 733e80f334e7..254ea3efe954 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1474,7 +1474,7 @@ static long do_wait(struct wait_opts *wo) return retval; } -static struct pid *pidfd_get_pid(unsigned int fd) +static struct pid *pidfd_get_pid(unsigned int fd, unsigned int *flags) { struct fd f; struct pid *pid; @@ -1484,8 +1484,10 @@ static struct pid *pidfd_get_pid(unsigned int fd) return ERR_PTR(-EBADF); pid = pidfd_pid(f.file); - if (!IS_ERR(pid)) + if (!IS_ERR(pid)) { get_pid(pid); + *flags = f.file->f_flags; + } fdput(f); return pid; @@ -1498,6 +1500,7 @@ static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop, struct pid *pid = NULL; enum pid_type type; long ret; + unsigned int f_flags = 0; if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED| __WNOTHREAD|__WCLONE|__WALL)) @@ -1531,9 +1534,10 @@ static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop, if (upid < 0) return -EINVAL; - pid = pidfd_get_pid(upid); + pid = pidfd_get_pid(upid, &f_flags); if (IS_ERR(pid)) return PTR_ERR(pid); + break; default: return -EINVAL; @@ -1544,7 +1548,12 @@ static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop, wo.wo_flags = options; wo.wo_info = infop; wo.wo_rusage = ru; + if (f_flags & O_NONBLOCK) + wo.wo_flags |= WNOHANG; + ret = do_wait(&wo); + if (!ret && (f_flags & O_NONBLOCK)) + ret = -EAGAIN; put_pid(pid); return ret; From patchwork Wed Sep 2 10:21:29 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 11750263 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6490D166C for ; Wed, 2 Sep 2020 10:23:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4E9D22084C for ; Wed, 2 Sep 2020 10:23:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726406AbgIBKXZ (ORCPT ); Wed, 2 Sep 2020 06:23:25 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:49497 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726226AbgIBKXX (ORCPT ); Wed, 2 Sep 2020 06:23:23 -0400 Received: from ip5f5af70b.dynamic.kabel-deutschland.de ([95.90.247.11] helo=wittgenstein.fritz.box) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1kDPvD-00069F-Kh; Wed, 02 Sep 2020 10:23:19 +0000 From: Christian Brauner To: linux-kernel@vger.kernel.org Cc: Christian Brauner , "Peter Zijlstra (Intel)" , Ingo Molnar , Thomas Gleixner , Oleg Nesterov , "Eric W. Biederman" , Kees Cook , Sargun Dhillon , Aleksa Sarai , linux-kselftest@vger.kernel.org, Josh Triplett , Jens Axboe , linux-api@vger.kernel.org, Christian Brauner , Shuah Khan Subject: [PATCH v2 3/4] tests: port pidfd_wait to kselftest harness Date: Wed, 2 Sep 2020 12:21:29 +0200 Message-Id: <20200902102130.147672-4-christian.brauner@ubuntu.com> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200902102130.147672-1-christian.brauner@ubuntu.com> References: <20200902102130.147672-1-christian.brauner@ubuntu.com> MIME-Version: 1.0 Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org All of the new pidfd selftests already use the new kselftest harness infrastructure. It makes for clearer output, makes the code easier to understand, and makes adding new tests way simpler. Cc: Shuah Khan Cc: linux-kselftest@vger.kernel.org Signed-off-by: Christian Brauner --- /* v2 */ unchanged --- tools/testing/selftests/pidfd/pidfd_wait.c | 213 ++++----------------- 1 file changed, 39 insertions(+), 174 deletions(-) diff --git a/tools/testing/selftests/pidfd/pidfd_wait.c b/tools/testing/selftests/pidfd/pidfd_wait.c index 7079f8eef792..075c716f6fb8 100644 --- a/tools/testing/selftests/pidfd/pidfd_wait.c +++ b/tools/testing/selftests/pidfd/pidfd_wait.c @@ -17,7 +17,7 @@ #include #include "pidfd.h" -#include "../kselftest.h" +#include "../kselftest_harness.h" #define ptr_to_u64(ptr) ((__u64)((uintptr_t)(ptr))) @@ -32,9 +32,8 @@ static int sys_waitid(int which, pid_t pid, siginfo_t *info, int options, return syscall(__NR_waitid, which, pid, info, options, ru); } -static int test_pidfd_wait_simple(void) +TEST(wait_simple) { - const char *test_name = "pidfd wait simple"; int pidfd = -1, status = 0; pid_t parent_tid = -1; struct clone_args args = { @@ -50,76 +49,40 @@ static int test_pidfd_wait_simple(void) }; pidfd = open("/proc/self", O_DIRECTORY | O_RDONLY | O_CLOEXEC); - if (pidfd < 0) - ksft_exit_fail_msg("%s test: failed to open /proc/self %s\n", - test_name, strerror(errno)); + ASSERT_GE(pidfd, 0); pid = sys_waitid(P_PIDFD, pidfd, &info, WEXITED, NULL); - if (pid == 0) - ksft_exit_fail_msg( - "%s test: succeeded to wait on invalid pidfd %s\n", - test_name, strerror(errno)); - close(pidfd); + ASSERT_NE(pid, 0); + EXPECT_EQ(close(pidfd), 0); pidfd = -1; pidfd = open("/dev/null", O_RDONLY | O_CLOEXEC); - if (pidfd == 0) - ksft_exit_fail_msg("%s test: failed to open /dev/null %s\n", - test_name, strerror(errno)); + ASSERT_GE(pidfd, 0); pid = sys_waitid(P_PIDFD, pidfd, &info, WEXITED, NULL); - if (pid == 0) - ksft_exit_fail_msg( - "%s test: succeeded to wait on invalid pidfd %s\n", - test_name, strerror(errno)); - close(pidfd); + ASSERT_NE(pid, 0); + EXPECT_EQ(close(pidfd), 0); pidfd = -1; pid = sys_clone3(&args); - if (pid < 0) - ksft_exit_fail_msg("%s test: failed to create new process %s\n", - test_name, strerror(errno)); + ASSERT_GE(pid, 1); if (pid == 0) exit(EXIT_SUCCESS); pid = sys_waitid(P_PIDFD, pidfd, &info, WEXITED, NULL); - if (pid < 0) - ksft_exit_fail_msg( - "%s test: failed to wait on process with pid %d and pidfd %d: %s\n", - test_name, parent_tid, pidfd, strerror(errno)); - - if (!WIFEXITED(info.si_status) || WEXITSTATUS(info.si_status)) - ksft_exit_fail_msg( - "%s test: unexpected status received after waiting on process with pid %d and pidfd %d: %s\n", - test_name, parent_tid, pidfd, strerror(errno)); - close(pidfd); - - if (info.si_signo != SIGCHLD) - ksft_exit_fail_msg( - "%s test: unexpected si_signo value %d received after waiting on process with pid %d and pidfd %d: %s\n", - test_name, info.si_signo, parent_tid, pidfd, - strerror(errno)); - - if (info.si_code != CLD_EXITED) - ksft_exit_fail_msg( - "%s test: unexpected si_code value %d received after waiting on process with pid %d and pidfd %d: %s\n", - test_name, info.si_code, parent_tid, pidfd, - strerror(errno)); - - if (info.si_pid != parent_tid) - ksft_exit_fail_msg( - "%s test: unexpected si_pid value %d received after waiting on process with pid %d and pidfd %d: %s\n", - test_name, info.si_pid, parent_tid, pidfd, - strerror(errno)); - - ksft_test_result_pass("%s test: Passed\n", test_name); - return 0; + ASSERT_GE(pid, 0); + ASSERT_EQ(WIFEXITED(info.si_status), true); + ASSERT_EQ(WEXITSTATUS(info.si_status), 0); + EXPECT_EQ(close(pidfd), 0); + + ASSERT_EQ(info.si_signo, SIGCHLD); + ASSERT_EQ(info.si_code, CLD_EXITED); + ASSERT_EQ(info.si_pid, parent_tid); } -static int test_pidfd_wait_states(void) +TEST(wait_states) { - const char *test_name = "pidfd wait states"; int pidfd = -1, status = 0; pid_t parent_tid = -1; struct clone_args args = { @@ -135,9 +98,7 @@ static int test_pidfd_wait_states(void) }; pid = sys_clone3(&args); - if (pid < 0) - ksft_exit_fail_msg("%s test: failed to create new process %s\n", - test_name, strerror(errno)); + ASSERT_GE(pid, 0); if (pid == 0) { kill(getpid(), SIGSTOP); @@ -145,127 +106,31 @@ static int test_pidfd_wait_states(void) exit(EXIT_SUCCESS); } - ret = sys_waitid(P_PIDFD, pidfd, &info, WSTOPPED, NULL); - if (ret < 0) - ksft_exit_fail_msg( - "%s test: failed to wait on WSTOPPED process with pid %d and pidfd %d: %s\n", - test_name, parent_tid, pidfd, strerror(errno)); - - if (info.si_signo != SIGCHLD) - ksft_exit_fail_msg( - "%s test: unexpected si_signo value %d received after waiting on process with pid %d and pidfd %d: %s\n", - test_name, info.si_signo, parent_tid, pidfd, - strerror(errno)); - - if (info.si_code != CLD_STOPPED) - ksft_exit_fail_msg( - "%s test: unexpected si_code value %d received after waiting on process with pid %d and pidfd %d: %s\n", - test_name, info.si_code, parent_tid, pidfd, - strerror(errno)); - - if (info.si_pid != parent_tid) - ksft_exit_fail_msg( - "%s test: unexpected si_pid value %d received after waiting on process with pid %d and pidfd %d: %s\n", - test_name, info.si_pid, parent_tid, pidfd, - strerror(errno)); - - ret = sys_pidfd_send_signal(pidfd, SIGCONT, NULL, 0); - if (ret < 0) - ksft_exit_fail_msg( - "%s test: failed to send signal to process with pid %d and pidfd %d: %s\n", - test_name, parent_tid, pidfd, strerror(errno)); - - ret = sys_waitid(P_PIDFD, pidfd, &info, WCONTINUED, NULL); - if (ret < 0) - ksft_exit_fail_msg( - "%s test: failed to wait WCONTINUED on process with pid %d and pidfd %d: %s\n", - test_name, parent_tid, pidfd, strerror(errno)); + ASSERT_EQ(sys_waitid(P_PIDFD, pidfd, &info, WSTOPPED, NULL), 0); + ASSERT_EQ(info.si_signo, SIGCHLD); + ASSERT_EQ(info.si_code, CLD_STOPPED); + ASSERT_EQ(info.si_pid, parent_tid); - if (info.si_signo != SIGCHLD) - ksft_exit_fail_msg( - "%s test: unexpected si_signo value %d received after waiting on process with pid %d and pidfd %d: %s\n", - test_name, info.si_signo, parent_tid, pidfd, - strerror(errno)); + ASSERT_EQ(sys_pidfd_send_signal(pidfd, SIGCONT, NULL, 0), 0); - if (info.si_code != CLD_CONTINUED) - ksft_exit_fail_msg( - "%s test: unexpected si_code value %d received after waiting on process with pid %d and pidfd %d: %s\n", - test_name, info.si_code, parent_tid, pidfd, - strerror(errno)); + ASSERT_EQ(sys_waitid(P_PIDFD, pidfd, &info, WCONTINUED, NULL), 0); + ASSERT_EQ(info.si_signo, SIGCHLD); + ASSERT_EQ(info.si_code, CLD_CONTINUED); + ASSERT_EQ(info.si_pid, parent_tid); - if (info.si_pid != parent_tid) - ksft_exit_fail_msg( - "%s test: unexpected si_pid value %d received after waiting on process with pid %d and pidfd %d: %s\n", - test_name, info.si_pid, parent_tid, pidfd, - strerror(errno)); + ASSERT_EQ(sys_waitid(P_PIDFD, pidfd, &info, WUNTRACED, NULL), 0); + ASSERT_EQ(info.si_signo, SIGCHLD); + ASSERT_EQ(info.si_code, CLD_STOPPED); + ASSERT_EQ(info.si_pid, parent_tid); - ret = sys_waitid(P_PIDFD, pidfd, &info, WUNTRACED, NULL); - if (ret < 0) - ksft_exit_fail_msg( - "%s test: failed to wait on WUNTRACED process with pid %d and pidfd %d: %s\n", - test_name, parent_tid, pidfd, strerror(errno)); + ASSERT_EQ(sys_pidfd_send_signal(pidfd, SIGKILL, NULL, 0), 0); - if (info.si_signo != SIGCHLD) - ksft_exit_fail_msg( - "%s test: unexpected si_signo value %d received after waiting on process with pid %d and pidfd %d: %s\n", - test_name, info.si_signo, parent_tid, pidfd, - strerror(errno)); + ASSERT_EQ(sys_waitid(P_PIDFD, pidfd, &info, WEXITED, NULL), 0); + ASSERT_EQ(info.si_signo, SIGCHLD); + ASSERT_EQ(info.si_code, CLD_KILLED); + ASSERT_EQ(info.si_pid, parent_tid); - if (info.si_code != CLD_STOPPED) - ksft_exit_fail_msg( - "%s test: unexpected si_code value %d received after waiting on process with pid %d and pidfd %d: %s\n", - test_name, info.si_code, parent_tid, pidfd, - strerror(errno)); - - if (info.si_pid != parent_tid) - ksft_exit_fail_msg( - "%s test: unexpected si_pid value %d received after waiting on process with pid %d and pidfd %d: %s\n", - test_name, info.si_pid, parent_tid, pidfd, - strerror(errno)); - - ret = sys_pidfd_send_signal(pidfd, SIGKILL, NULL, 0); - if (ret < 0) - ksft_exit_fail_msg( - "%s test: failed to send SIGKILL to process with pid %d and pidfd %d: %s\n", - test_name, parent_tid, pidfd, strerror(errno)); - - ret = sys_waitid(P_PIDFD, pidfd, &info, WEXITED, NULL); - if (ret < 0) - ksft_exit_fail_msg( - "%s test: failed to wait on WEXITED process with pid %d and pidfd %d: %s\n", - test_name, parent_tid, pidfd, strerror(errno)); - - if (info.si_signo != SIGCHLD) - ksft_exit_fail_msg( - "%s test: unexpected si_signo value %d received after waiting on process with pid %d and pidfd %d: %s\n", - test_name, info.si_signo, parent_tid, pidfd, - strerror(errno)); - - if (info.si_code != CLD_KILLED) - ksft_exit_fail_msg( - "%s test: unexpected si_code value %d received after waiting on process with pid %d and pidfd %d: %s\n", - test_name, info.si_code, parent_tid, pidfd, - strerror(errno)); - - if (info.si_pid != parent_tid) - ksft_exit_fail_msg( - "%s test: unexpected si_pid value %d received after waiting on process with pid %d and pidfd %d: %s\n", - test_name, info.si_pid, parent_tid, pidfd, - strerror(errno)); - - close(pidfd); - - ksft_test_result_pass("%s test: Passed\n", test_name); - return 0; + EXPECT_EQ(close(pidfd), 0); } -int main(int argc, char **argv) -{ - ksft_print_header(); - ksft_set_plan(2); - - test_pidfd_wait_simple(); - test_pidfd_wait_states(); - - return ksft_exit_pass(); -} +TEST_HARNESS_MAIN From patchwork Wed Sep 2 10:21:30 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 11750261 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 0A3F0166C for ; Wed, 2 Sep 2020 10:23:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F19112098B for ; Wed, 2 Sep 2020 10:23:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726448AbgIBKX0 (ORCPT ); Wed, 2 Sep 2020 06:23:26 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:49502 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726247AbgIBKXX (ORCPT ); Wed, 2 Sep 2020 06:23:23 -0400 Received: from ip5f5af70b.dynamic.kabel-deutschland.de ([95.90.247.11] helo=wittgenstein.fritz.box) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1kDPvE-00069F-Af; Wed, 02 Sep 2020 10:23:20 +0000 From: Christian Brauner To: linux-kernel@vger.kernel.org Cc: Christian Brauner , "Peter Zijlstra (Intel)" , Ingo Molnar , Thomas Gleixner , Oleg Nesterov , "Eric W. Biederman" , Kees Cook , Sargun Dhillon , Aleksa Sarai , linux-kselftest@vger.kernel.org, Josh Triplett , Jens Axboe , linux-api@vger.kernel.org, Christian Brauner , Shuah Khan Subject: [PATCH v2 4/4] tests: add waitid() tests for non-blocking pidfds Date: Wed, 2 Sep 2020 12:21:30 +0200 Message-Id: <20200902102130.147672-5-christian.brauner@ubuntu.com> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200902102130.147672-1-christian.brauner@ubuntu.com> References: <20200902102130.147672-1-christian.brauner@ubuntu.com> MIME-Version: 1.0 Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Verify that the PIDFD_NONBLOCK flag works with pidfd_open() and that waitid() with a non-blocking pidfd returns EAGAIN: TAP version 13 1..3 # Starting 3 tests from 1 test cases. # RUN global.wait_simple ... # OK global.wait_simple ok 1 global.wait_simple # RUN global.wait_states ... # OK global.wait_states ok 2 global.wait_states # RUN global.wait_nonblock ... # OK global.wait_nonblock ok 3 global.wait_nonblock # PASSED: 3 / 3 tests passed. # Totals: pass:3 fail:0 xfail:0 xpass:0 skip:0 error:0 Cc: Shuah Khan Cc: linux-kselftest@vger.kernel.org Signed-off-by: Christian Brauner --- /* v2 */ unchanged --- tools/testing/selftests/pidfd/pidfd.h | 4 ++ tools/testing/selftests/pidfd/pidfd_wait.c | 83 +++++++++++++++++++++- 2 files changed, 86 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/pidfd/pidfd.h b/tools/testing/selftests/pidfd/pidfd.h index a2c80914e3dc..01f8d3c0cf2c 100644 --- a/tools/testing/selftests/pidfd/pidfd.h +++ b/tools/testing/selftests/pidfd/pidfd.h @@ -46,6 +46,10 @@ #define __NR_pidfd_getfd -1 #endif +#ifndef PIDFD_NONBLOCK +#define PIDFD_NONBLOCK O_NONBLOCK +#endif + /* * The kernel reserves 300 pids via RESERVED_PIDS in kernel/pid.c * That means, when it wraps around any pid < 300 will be skipped. diff --git a/tools/testing/selftests/pidfd/pidfd_wait.c b/tools/testing/selftests/pidfd/pidfd_wait.c index 075c716f6fb8..cefce4d3d2f6 100644 --- a/tools/testing/selftests/pidfd/pidfd_wait.c +++ b/tools/testing/selftests/pidfd/pidfd_wait.c @@ -21,6 +21,11 @@ #define ptr_to_u64(ptr) ((__u64)((uintptr_t)(ptr))) +/* Attempt to de-conflict with the selftests tree. */ +#ifndef SKIP +#define SKIP(s, ...) XFAIL(s, ##__VA_ARGS__) +#endif + static pid_t sys_clone3(struct clone_args *args) { return syscall(__NR_clone3, args, sizeof(struct clone_args)); @@ -65,7 +70,7 @@ TEST(wait_simple) pidfd = -1; pid = sys_clone3(&args); - ASSERT_GE(pid, 1); + ASSERT_GE(pid, 0); if (pid == 0) exit(EXIT_SUCCESS); @@ -133,4 +138,80 @@ TEST(wait_states) EXPECT_EQ(close(pidfd), 0); } +TEST(wait_nonblock) +{ + int pidfd, status = 0; + unsigned int flags = 0; + pid_t parent_tid = -1; + struct clone_args args = { + .parent_tid = ptr_to_u64(&parent_tid), + .flags = CLONE_PARENT_SETTID, + .exit_signal = SIGCHLD, + }; + int ret; + pid_t pid; + siginfo_t info = { + .si_signo = 0, + }; + + /* + * Callers need to see ECHILD with non-blocking pidfds when no child + * processes exists. + */ + pidfd = sys_pidfd_open(getpid(), PIDFD_NONBLOCK); + EXPECT_GE(pidfd, 0) { + /* pidfd_open() doesn't support PIDFD_NONBLOCK. */ + ASSERT_EQ(errno, EINVAL); + SKIP(return, "Skipping PIDFD_NONBLOCK test"); + } + + pid = sys_waitid(P_PIDFD, pidfd, &info, WEXITED, NULL); + ASSERT_LT(pid, 0); + ASSERT_EQ(errno, ECHILD); + EXPECT_EQ(close(pidfd), 0); + + pid = sys_clone3(&args); + ASSERT_GE(pid, 0); + + if (pid == 0) { + kill(getpid(), SIGSTOP); + exit(EXIT_SUCCESS); + } + + pidfd = sys_pidfd_open(pid, PIDFD_NONBLOCK); + EXPECT_GE(pidfd, 0) { + /* pidfd_open() doesn't support PIDFD_NONBLOCK. */ + ASSERT_EQ(errno, EINVAL); + SKIP(return, "Skipping PIDFD_NONBLOCK test"); + } + + flags = fcntl(pidfd, F_GETFL, 0); + ASSERT_GT(flags, 0); + ASSERT_GT((flags & O_NONBLOCK), 0); + + /* + * Callers need to see EAGAIN/EWOULDBLOCK with non-blocking pidfd when + * child processes exist but none have exited. + */ + pid = sys_waitid(P_PIDFD, pidfd, &info, WEXITED, NULL); + ASSERT_LT(pid, 0); + ASSERT_EQ(errno, EAGAIN); + + ASSERT_EQ(sys_waitid(P_PIDFD, pidfd, &info, WSTOPPED, NULL), 0); + ASSERT_EQ(info.si_signo, SIGCHLD); + ASSERT_EQ(info.si_code, CLD_STOPPED); + ASSERT_EQ(info.si_pid, parent_tid); + + ASSERT_EQ(sys_pidfd_send_signal(pidfd, SIGCONT, NULL, 0), 0); + + ASSERT_EQ(fcntl(pidfd, F_SETFL, (flags & ~O_NONBLOCK)), 0); + + ASSERT_EQ(sys_waitid(P_PIDFD, pidfd, &info, WEXITED, NULL), 0); + ASSERT_EQ(info.si_signo, SIGCHLD); + ASSERT_EQ(info.si_code, CLD_EXITED); + ASSERT_EQ(info.si_pid, parent_tid); + + EXPECT_EQ(close(pidfd), 0); +} + TEST_HARNESS_MAIN