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restore: Switch to the new ns_last_pid kernel facility while forking children

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Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
This commit is contained in:
Cyrill Gorcunov
2011-12-01 18:21:17 +04:00
parent 762a5a16a7
commit 8d36f08765
2 changed files with 41 additions and 17 deletions
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54
cr-restore.c
View File

@@ -16,6 +16,7 @@
#include <sys/ptrace.h> #include <sys/ptrace.h>
#include <sys/user.h> #include <sys/user.h>
#include <sys/wait.h> #include <sys/wait.h>
#include <sys/file.h>
#include <sched.h> #include <sched.h>
@@ -1154,29 +1155,50 @@ static int restore_one_task(int pid)
return prepare_and_sigreturn(pid); return prepare_and_sigreturn(pid);
} }
static int do_child(void *arg)
{
return restore_task_with_children(getpid(), arg);
}
static inline int fork_with_pid(int pid, char *pstree_path) static inline int fork_with_pid(int pid, char *pstree_path)
{ {
const int stack_size = 32 << 10; int ret = -1, fd = -1;
int ret = 0; char buf[32];
void *stack;
stack = mmap(0, stack_size, PROT_READ | PROT_WRITE, snprintf(buf, sizeof(buf), "%d", pid - 1);
MAP_PRIVATE | MAP_ANON | MAP_GROWSDOWN, 0, 0);
if (stack == MAP_FAILED) { fd = open(LAST_PID_PATH, O_RDWR);
pr_perror("%d: mmap failed\n", pid); if (fd < 0) {
pr_perror("%d: Can't open %s\n", pid, LAST_PID_PATH);
goto err;
}
if (flock(fd, LOCK_EX)) {
pr_perror("%d: Can't lock %s\n", pid, LAST_PID_PATH);
goto err;
}
write_safe(fd, buf, strlen(buf), err_unlock);
ret = fork();
if (ret < 0) {
pr_perror("Can't fork for %d\n", pid);
goto err_unlock;
} else if (!ret) {
int my_pid = getpid();
close_safe(&fd);
if (my_pid != pid) {
pr_err("%d: Pids do not match got %d but expected %d\n",
my_pid, my_pid, pid);
return -1; return -1;
} }
stack += stack_size; return restore_task_with_children(my_pid, pstree_path);
ret = clone(do_child, stack, SIGCHLD | CLONE_CHILD_USEPID, pstree_path, NULL, NULL, &pid); }
if (ret < 0)
pr_perror("%d: clone failed\n", pid);
err_unlock:
if (flock(fd, LOCK_UN))
pr_perror("%d: Can't unlock %s\n", pid, LAST_PID_PATH);
err:
close_safe(&fd);
return ret; return ret;
} }

2
include/crtools.h
View File

@@ -54,6 +54,8 @@ struct cr_fd_desc_tmpl {
#define FMT_FNAME_VMAS "vmas-%d.img" #define FMT_FNAME_VMAS "vmas-%d.img"
#define FMT_FNAME_SIGACTS "sigacts-%d.img" #define FMT_FNAME_SIGACTS "sigacts-%d.img"
#define LAST_PID_PATH "/proc/sys/kernel/ns_last_pid"
/* file descriptors */ /* file descriptors */
struct cr_fd_desc { struct cr_fd_desc {
struct cr_fd_desc_tmpl *tmpl; /* template we refer to */ struct cr_fd_desc_tmpl *tmpl; /* template we refer to */