diff options
| -rw-r--r-- | include/qemu/async-teardown.h | 22 | ||||
| -rw-r--r-- | meson.build | 1 | ||||
| -rw-r--r-- | os-posix.c | 6 | ||||
| -rw-r--r-- | qemu-options.hx | 19 | ||||
| -rw-r--r-- | util/async-teardown.c | 150 | ||||
| -rw-r--r-- | util/meson.build | 1 |
6 files changed, 199 insertions, 0 deletions
diff --git a/include/qemu/async-teardown.h b/include/qemu/async-teardown.h new file mode 100644 index 0000000000..092e7a37e7 --- /dev/null +++ b/include/qemu/async-teardown.h @@ -0,0 +1,22 @@ +/* + * Asynchronous teardown + * + * Copyright IBM, Corp. 2022 + * + * Authors: + * Claudio Imbrenda <imbrenda@linux.ibm.com> + * + * This work is licensed under the terms of the GNU GPL, version 2 or (at your + * option) any later version. See the COPYING file in the top-level directory. + * + */ +#ifndef QEMU_ASYNC_TEARDOWN_H +#define QEMU_ASYNC_TEARDOWN_H + +#include "config-host.h" + +#ifdef CONFIG_LINUX +void init_async_teardown(void); +#endif + +#endif diff --git a/meson.build b/meson.build index 37737913df..17834b3c3d 100644 --- a/meson.build +++ b/meson.build @@ -1949,6 +1949,7 @@ if targetos == 'windows' endif # has_function +config_host_data.set('CONFIG_CLOSE_RANGE', cc.has_function('close_range')) config_host_data.set('CONFIG_ACCEPT4', cc.has_function('accept4')) config_host_data.set('CONFIG_CLOCK_ADJTIME', cc.has_function('clock_adjtime')) config_host_data.set('CONFIG_DUP3', cc.has_function('dup3')) diff --git a/os-posix.c b/os-posix.c index 321fc4bd13..4858650c3e 100644 --- a/os-posix.c +++ b/os-posix.c @@ -39,6 +39,7 @@ #ifdef CONFIG_LINUX #include <sys/prctl.h> +#include "qemu/async-teardown.h" #endif /* @@ -150,6 +151,11 @@ int os_parse_cmd_args(int index, const char *optarg) case QEMU_OPTION_daemonize: daemonize = 1; break; +#if defined(CONFIG_LINUX) + case QEMU_OPTION_asyncteardown: + init_async_teardown(); + break; +#endif default: return -1; } diff --git a/qemu-options.hx b/qemu-options.hx index eb38e5dc40..e26d1dad39 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -4774,6 +4774,25 @@ HXCOMM Internal use DEF("qtest", HAS_ARG, QEMU_OPTION_qtest, "", QEMU_ARCH_ALL) DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL) +#ifdef __linux__ +DEF("async-teardown", 0, QEMU_OPTION_asyncteardown, + "-async-teardown enable asynchronous teardown\n", + QEMU_ARCH_ALL) +#endif +SRST +``-async-teardown`` + Enable asynchronous teardown. A new process called "cleanup/<QEMU_PID>" + will be created at startup sharing the address space with the main qemu + process, using clone. It will wait for the main qemu process to + terminate completely, and then exit. + This allows qemu to terminate very quickly even if the guest was + huge, leaving the teardown of the address space to the cleanup + process. Since the cleanup process shares the same cgroups as the + main qemu process, accounting is performed correctly. This only + works if the cleanup process is not forcefully killed with SIGKILL + before the main qemu process has terminated completely. +ERST + DEF("msg", HAS_ARG, QEMU_OPTION_msg, "-msg [timestamp[=on|off]][,guest-name=[on|off]]\n" " control error message format\n" diff --git a/util/async-teardown.c b/util/async-teardown.c new file mode 100644 index 0000000000..62bfce1b3c --- /dev/null +++ b/util/async-teardown.c @@ -0,0 +1,150 @@ +/* + * Asynchronous teardown + * + * Copyright IBM, Corp. 2022 + * + * Authors: + * Claudio Imbrenda <imbrenda@linux.ibm.com> + * + * This work is licensed under the terms of the GNU GPL, version 2 or (at your + * option) any later version. See the COPYING file in the top-level directory. + * + */ +#include <stdlib.h> +#include <stdio.h> +#include <sys/types.h> +#include <dirent.h> +#include <sys/prctl.h> +#include <signal.h> +#include <sched.h> +#include <unistd.h> + +#include "qemu/osdep.h" +#include "qemu/async-teardown.h" + +#ifdef _SC_THREAD_STACK_MIN +#define CLONE_STACK_SIZE sysconf(_SC_THREAD_STACK_MIN) +#else +#define CLONE_STACK_SIZE 16384 +#endif + +static pid_t the_ppid; + +/* + * Close all open file descriptors. + */ +static void close_all_open_fd(void) +{ + struct dirent *de; + int fd, dfd; + DIR *dir; + +#ifdef CONFIG_CLOSE_RANGE + int r = close_range(0, ~0U, 0); + if (!r) { + /* Success, no need to try other ways. */ + return; + } +#endif + + dir = opendir("/proc/self/fd"); + if (!dir) { + /* If /proc is not mounted, there is nothing that can be done. */ + return; + } + /* Avoid closing the directory. */ + dfd = dirfd(dir); + + for (de = readdir(dir); de; de = readdir(dir)) { + fd = atoi(de->d_name); + if (fd != dfd) { + close(fd); + } + } + closedir(dir); +} + +static void hup_handler(int signal) +{ + /* Check every second if this process has been reparented. */ + while (the_ppid == getppid()) { + /* sleep() is safe to use in a signal handler. */ + sleep(1); + } + + /* At this point the parent process has terminated completely. */ + _exit(0); +} + +static int async_teardown_fn(void *arg) +{ + struct sigaction sa = { .sa_handler = hup_handler }; + sigset_t hup_signal; + char name[16]; + + /* Set a meaningful name for this process. */ + snprintf(name, 16, "cleanup/%d", the_ppid); + prctl(PR_SET_NAME, (unsigned long)name); + + /* + * Close all file descriptors that might have been inherited from the + * main qemu process when doing clone, needed to make libvirt happy. + * Not using close_range for increased compatibility with older kernels. + */ + close_all_open_fd(); + + /* Set up a handler for SIGHUP and unblock SIGHUP. */ + sigaction(SIGHUP, &sa, NULL); + sigemptyset(&hup_signal); + sigaddset(&hup_signal, SIGHUP); + sigprocmask(SIG_UNBLOCK, &hup_signal, NULL); + + /* Ask to receive SIGHUP when the parent dies. */ + prctl(PR_SET_PDEATHSIG, SIGHUP); + + /* + * Sleep forever, unless the parent process has already terminated. The + * only interruption can come from the SIGHUP signal, which in normal + * operation is received when the parent process dies. + */ + if (the_ppid == getppid()) { + pause(); + } + + /* At this point the parent process has terminated completely. */ + _exit(0); +} + +/* + * Allocate a new stack of a reasonable size, and return a pointer to its top. + */ +static void *new_stack_for_clone(void) +{ + size_t stack_size = CLONE_STACK_SIZE; + char *stack_ptr; + + /* Allocate a new stack and get a pointer to its top. */ + stack_ptr = qemu_alloc_stack(&stack_size); +#if !defined(HOST_HPPA) + /* The top is at the end of the area, except on HPPA. */ + stack_ptr += stack_size; +#endif + + return stack_ptr; +} + +/* + * Block all signals, start (clone) a new process sharing the address space + * with qemu (CLONE_VM), then restore signals. + */ +void init_async_teardown(void) +{ + sigset_t all_signals, old_signals; + + the_ppid = getpid(); + + sigfillset(&all_signals); + sigprocmask(SIG_BLOCK, &all_signals, &old_signals); + clone(async_teardown_fn, new_stack_for_clone(), CLONE_VM, NULL); + sigprocmask(SIG_SETMASK, &old_signals, NULL); +} diff --git a/util/meson.build b/util/meson.build index 5e282130df..63acd59bb0 100644 --- a/util/meson.build +++ b/util/meson.build @@ -2,6 +2,7 @@ util_ss.add(files('osdep.c', 'cutils.c', 'unicode.c', 'qemu-timer-common.c')) if not config_host_data.get('CONFIG_ATOMIC64') util_ss.add(files('atomic64.c')) endif +util_ss.add(when: 'CONFIG_LINUX', if_true: files('async-teardown.c')) util_ss.add(when: 'CONFIG_POSIX', if_true: files('aio-posix.c')) util_ss.add(when: 'CONFIG_POSIX', if_true: files('fdmon-poll.c')) if config_host_data.get('CONFIG_EPOLL_CREATE1') |