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utils: Make call_in_child_process() use parent's stack

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1)Use CLONE_VFORK to create subprocess, as it's safe after patch
"clone_noasan: Allow to create CLONE_VM|CLONE_VFORK processe".

2)add more CLONE_XXX to flags to speedup the syscall.

3)Do not send SIGCHLD, as parent sees child's exit() synchronuos anyway.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
This commit is contained in:
Kirill Tkhai 2017-05-17 17:37:13 +03:00 committed by Andrei Vagin
parent 0315082e06
commit 522d9c7180
1 changed files with 12 additions and 31 deletions
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43
criu/util.c
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@ -47,6 +47,7 @@
#include "namespaces.h"
#include "criu-log.h"
#include "clone-noasan.h"
#include "cr_options.h"
#include "servicefd.h"
#include "cr-service.h"
@ -1423,50 +1424,30 @@ int open_fd_of_real_pid(pid_t pid, int fd, int flags)
int call_in_child_process(int (*fn)(void *), void *arg)
{
sigset_t blockmask, oldmask;
int size, status, ret = -1;
char *stack;
int status, ret = -1;
pid_t pid;
size = 2 * 1024 * 1024; /* 2Mb */
stack = mmap(NULL, size, PROT_WRITE | PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
if (stack == MAP_FAILED) {
pr_perror("Can't allocate stack");
return -1;
}
sigemptyset(&blockmask);
sigaddset(&blockmask, SIGCHLD);
if (sigprocmask(SIG_BLOCK, &blockmask, &oldmask) == -1) {
pr_perror("Can not set mask of blocked signals");
goto out_munmap;
}
pid = clone(fn, stack + size, CLONE_VM | CLONE_FILES | SIGCHLD, arg);
/*
* Parent freezes till child exit, so child may use the same stack.
* No SIGCHLD flag, so it's not need to block signal.
*/
pid = clone_noasan(fn, CLONE_VFORK | CLONE_VM | CLONE_FILES |
CLONE_IO | CLONE_SIGHAND | CLONE_SYSVSEM, arg);
if (pid == -1) {
pr_perror("Can't clone");
goto out_unblock;
return -1;
}
errno = 0;
if (waitpid(pid, &status, 0) != pid || !WIFEXITED(status) || WEXITSTATUS(status)) {
if (waitpid(pid, &status, __WALL) != pid || !WIFEXITED(status) || WEXITSTATUS(status)) {
pr_err("Can't wait or bad status: errno=%d, status=%d", errno, status);
goto out_close;
goto out;
}
ret = 0;
out_close:
/*
* Child opened PROC_SELF for pid. If we create one more child
* with the same pid later, it will try to reuse this /proc/self.
*/
out:
close_pid_proc();
out_unblock:
if (sigprocmask(SIG_SETMASK, &oldmask, NULL) == -1) {
pr_perror("Can not unset mask of blocked signals");
ret = -1;
}
out_munmap:
munmap(stack, size);
return ret;
}