util/async-teardown.c: move to softmmu/, only build it when system build is requested

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-ID: <20230901101302.3618955-9-mjt@tls.msk.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 0 insertions, 147 deletions

diff --git a/util/async-teardown.c b/util/async-teardown.c
deleted file mode 100644
index 62cdeb0f20..0000000000
--- a/util/async-teardown.c
+++ /dev/null
@@ -1,146 +0,0 @@
-/*
- * 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 "qemu/osdep.h"
-#include <dirent.h>
-#include <sys/prctl.h>
-#include <sched.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 a375160286..c4827fd70a 100644
--- a/util/meson.build
+++ b/util/meson.build
@@ -3,7 +3,6 @@ util_ss.add(files('thread-context.c'), numa)
 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')