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restore: Switch task fork-ing into clone-ing

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In order to restore task in namespaces we'll have to clone() them,
not fork. Thus switch the restorer into using clone.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
This commit is contained in:
Pavel Emelyanov
2012-01-26 15:26:00 +04:00
committed by Cyrill Gorcunov
parent 2e48f0528b
commit b5e5aac9e9
1 changed files with 42 additions and 34 deletions
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76
cr-restore.c
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@@ -101,7 +101,7 @@ static int nr_pipes;
static pid_t pstree_pid;
static int restore_task_with_children(int pid);
static int restore_task_with_children(void *);
static void sigreturn_restore(pid_t pstree_pid, pid_t pid);
static void show_saved_shmems(void)
@@ -1235,57 +1235,57 @@ static int restore_one_task(int pid)
}
}
#define STACK_SIZE (8 * 4096)
struct cr_clone_arg {
int pid, fd;
};
static inline int fork_with_pid(int pid)
{
int ret = -1, fd = -1;
int ret = -1;
char buf[32];
struct cr_clone_arg ca;
void *stack;
stack = mmap(NULL, STACK_SIZE, PROT_WRITE | PROT_READ,
MAP_PRIVATE | MAP_GROWSDOWN | MAP_ANONYMOUS, -1, 0);
if (stack == MAP_FAILED) {
pr_perror("Failed to map stack for kid\n");
goto err;
}
snprintf(buf, sizeof(buf), "%d", pid - 1);
fd = open(LAST_PID_PATH, O_RDWR);
if (fd < 0) {
ca.pid = pid;
ca.fd = open(LAST_PID_PATH, O_RDWR);
if (ca.fd < 0) {
pr_perror("%d: Can't open %s\n", pid, LAST_PID_PATH);
goto err;
}
if (flock(fd, LOCK_EX)) {
if (flock(ca.fd, LOCK_EX)) {
pr_perror("%d: Can't lock %s\n", pid, LAST_PID_PATH);
goto err;
}
if (write_img_buf(fd, buf, strlen(buf)))
if (write_img_buf(ca.fd, buf, strlen(buf)))
goto err_unlock;
ret = fork();
if (ret < 0) {
ret = clone(restore_task_with_children, stack + STACK_SIZE,
SIGCHLD, &ca);
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;
}
/*
* We should never return here.
*/
ret = restore_task_with_children(pid);
pr_err("%d: Something failed with code %d\n", pid, ret);
exit(1);
}
err_unlock:
if (flock(fd, LOCK_UN))
if (flock(ca.fd, LOCK_UN))
pr_perror("%d: Can't unlock %s\n", pid, LAST_PID_PATH);
err:
close_safe(&fd);
if (stack != MAP_FAILED)
munmap(stack, STACK_SIZE);
close_safe(&ca.fd);
return ret;
}
@@ -1303,12 +1303,22 @@ static void sigchld_handler(int signal, siginfo_t *siginfo, void *data)
cr_wait_set(&task_entries->nr_in_progress, -1);
}
static int restore_task_with_children(int pid)
static int restore_task_with_children(void *_arg)
{
struct cr_clone_arg *ca = _arg;
int *pids;
int fd, ret, i;
struct pstree_entry e;
sigset_t blockmask;
int pid;
close_safe(&ca->fd);
pid = getpid();
if (ca->pid != pid) {
pr_err("%d: Pid do not match expected %d\n", pid, ca->pid);
exit(-1);
}
/*
* The block mask will be restored in sigresturn.
@@ -1368,7 +1378,6 @@ static int restore_task_with_children(int pid)
pr_info("%d: Restoring %d children:\n", pid, e.nr_children);
for (i = 0; i < e.nr_children; i++) {
pr_info("\tFork %d from %d\n", pids[i], pid);
ret = fork_with_pid(pids[i]);
if (ret < 0)
exit(1);
@@ -1407,7 +1416,6 @@ static int restore_root_task(int fd, struct cr_options *opts)
return -1;
}
pr_info("Forking root with %d pid\n", e.pid);
ret = fork_with_pid(e.pid);
if (ret < 0)
return -1;