timers: Split posix timers restore into two stages

1st stage is -- creating the timers. It may fail if kernel
allocated IDs in a manner we don't expect or runs out of
memory.

2nd stage is -- arm the timers. It cannot fail, since we've
validated the timespecs in advance and should happen after
we've waited for all the other tasks to complete the restore.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

include/restorer.h

@@ -64,7 +64,7 @@ struct rst_sched_param {
 };
 
 struct str_posix_timer {
-	int it_id;
+	long it_id;
 	int clock_id;
 	int si_signo;
 	int it_sigev_notify;

pie/restorer.c

@@ -473,7 +473,7 @@ static int vma_remap(unsigned long src, unsigned long dst, unsigned long len)
 	return 0;
 }
 
-static int restore_posix_timers(struct task_restore_core_args *args)
+static int create_posix_timers(struct task_restore_core_args *args)
 {
 	int ret, i;
 	timer_t next_id;
@@ -505,17 +505,22 @@ static int restore_posix_timers(struct task_restore_core_args *args)
 				return -1;
 			}
 		}
-
-		ret = sys_timer_settime(next_id, 0, &args->posix_timers[i].val, NULL);
-		if (ret < 0) {
-			pr_err("Can't set posix timer %lx\n", (long) next_id);
-			return ret;
-		}
 	}
 
 	return 0;
 }
 
+static void restore_posix_timers(struct task_restore_core_args *args)
+{
+	int i;
+	struct restore_posix_timer *rt;
+
+	for (i = 0; i < args->timer_n; i++) {
+		rt = &args->posix_timers[i];
+		sys_timer_settime((timer_t)rt->spt.it_id, 0, &rt->val, NULL);
+	}
+}
+
 /*
  * The main routine to restore task via sigreturn.
  * This one is very special, we never return there
@@ -882,7 +887,7 @@ long __export_restore_task(struct task_restore_core_args *args)
 		}
 	}
 
-	ret = restore_posix_timers(args);
+	ret = create_posix_timers(args);
 	if (ret < 0) {
 		pr_err("Can't restore posix timers %ld\n", ret);
 		goto core_restore_end;
@@ -926,6 +931,8 @@ long __export_restore_task(struct task_restore_core_args *args)
 	if (itimer_armed(args, 2))
 		sys_setitimer(ITIMER_PROF, &args->itimers[2], NULL);
 
+	restore_posix_timers(args);
+
 	ret = sys_munmap(args->task_entries, TASK_ENTRIES_SIZE);
 	if (ret < 0) {
 		ret = ((long)__LINE__ << 16) | ((-ret) & 0xffff);

proc_parse.c

@@ -1210,7 +1210,7 @@ int parse_posix_timers(pid_t pid, struct proc_posix_timers_stat *args)
 
 		timer = xzalloc(sizeof(struct proc_posix_timer));
 
-		ret = sscanf(line1, "%s %d", str_name, &timer->spt.it_id);
+		ret = sscanf(line1, "%s %ld", str_name, &timer->spt.it_id);
 		if (ret != 2 || str_name[0] != 'I')
 			goto parse_err_posix;
 		ret = sscanf(line2, "%s %d%s", str_name, &timer->spt.si_signo, siginfo_tmp);