[Devel] [PATCH 2/2] Dump/restore start_time param from /proc/[pid]/stat for each task

[Valeriy Vdovin]

https://jira.sw.ru/browse/PSBM-100083
Signed-off-by: Valeriy Vdovin <valeriy.vdovin at virtuozzo.com>
---
 criu/cr-dump.c    | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 criu/cr-restore.c | 40 ++++++++++++++++++++++++++++++++++++++++
 images/core.proto |  2 ++
 3 files changed, 91 insertions(+)

diff --git a/criu/cr-dump.c b/criu/cr-dump.c
index 45626e8..859cfa9 100644
--- a/criu/cr-dump.c
+++ b/criu/cr-dump.c
@@ -1037,6 +1037,47 @@ int dump_thread_core(int pid, CoreEntry *core, const struct parasite_dump_thread
 	return ret;
 }
 
+struct get_internal_start_time_rq {
+	int pid;
+	unsigned long long result;
+};
+
+static int child_get_internal_start_time(void *arg)
+{
+	struct proc_pid_stat p;
+	struct get_internal_start_time_rq *r =
+		(struct get_internal_start_time_rq *)arg;
+
+	/* We need to join ve to access container relative
+	 * value of task's start_time, otherwize we will see
+	 * start_time visible to host.
+	 */
+	join_ve(r->pid, true);
+
+	parse_pid_stat(r->pid, &p);
+	r->result = p.start_time;
+	return 0;
+}
+
+static int dump_task_internal_start_time(int pid, TaskCoreEntry *tc)
+{
+	int ret;
+	struct get_internal_start_time_rq r = {
+		.pid = pid,
+		.result = 0
+	};
+
+	ret = call_in_child_process(child_get_internal_start_time, &r);
+	if (ret) {
+		pr_err("Failed to exec in child\n");
+		return ret;
+	}
+
+	tc->has_start_time = 1;
+	tc->start_time = r.result;
+	return 0;
+}
+
 static int dump_task_core_all(struct parasite_ctl *ctl,
 			      struct pstree_item *item,
 			      const struct proc_pid_stat *stat,
@@ -1063,6 +1104,14 @@ static int dump_task_core_all(struct parasite_ctl *ctl,
 	core->tc->task_state = item->pid->state;
 	core->tc->exit_code = 0;
 
+	ret = dump_task_internal_start_time(pid, core->tc);
+	if (ret) {
+		pr_err("Failed to dump start_time for task %d\n", pid);
+		goto err;
+	}
+
+	pr_info("Dumped start_time of task %d is %lu\n", pid, core->tc->start_time);
+
 	if (stat->tty_nr) {
 		struct pstree_item *p = item;
 
diff --git a/criu/cr-restore.c b/criu/cr-restore.c
index 170beab..fe04d67 100644
--- a/criu/cr-restore.c
+++ b/criu/cr-restore.c
@@ -947,6 +947,42 @@ static int prepare_proc_misc(pid_t pid, TaskCoreEntry *tc)
 static int prepare_itimers(int pid, struct task_restore_args *args, CoreEntry *core);
 static int prepare_mm(pid_t pid, struct task_restore_args *args);
 
+static int restore_start_time(int pid, CoreEntry *core)
+{
+	unsigned long long total_nsec;
+	unsigned long flags;
+	long tps;
+	struct prctl_task_ct_fields ct_fields;
+
+	if (!core) {
+		pr_err("Skipping restore_start_time for pid %d, core is NULL\n", pid);
+		return -1;
+	}
+
+	if (!core->tc->has_start_time) {
+		pr_warn("Skipping restore_start_time for old image version.\n");
+		return -1;
+	}
+
+	tps = sysconf(_SC_CLK_TCK);
+	if (tps == -1) {
+		pr_perror("Failed to get clock ticks via sysconf");
+		return -1;
+	}
+
+	total_nsec = core->tc->start_time * (NSEC_PER_SEC / tps);
+
+	ct_fields.real_start_time = total_nsec;
+	flags = PR_TASK_CT_FIELDS_START_TIME;
+
+	if (prctl(PR_SET_TASK_CT_FIELDS, (unsigned long)&ct_fields, flags, 0, 0)) {
+		pr_perror("Can't set process start time");
+		return -1;
+	}
+
+	return 0;
+}
+
 static int restore_one_alive_task(int pid, CoreEntry *core)
 {
 	unsigned args_len;
@@ -955,6 +991,10 @@ static int restore_one_alive_task(int pid, CoreEntry *core)
 
 	rst_mem_switch_to_private();
 
+	restore_start_time(pid, core);
+	pr_info("Restored start_time of task %d is %lu\n",
+		pid, core->tc->start_time);
+
 	args_len = round_up(sizeof(*ta) + sizeof(struct thread_restore_args) *
 			current->nr_threads, page_size());
 	ta = mmap(NULL, args_len, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
diff --git a/images/core.proto b/images/core.proto
index 6ef5f50..c2b6099 100644
--- a/images/core.proto
+++ b/images/core.proto
@@ -50,6 +50,7 @@ message task_core_entry_VZ730 {
 	optional int32			tty_nr		= 15;
 	optional int32			tty_pgrp	= 16;
 	repeated sa_entry		sigactions	= 17;
+	optional uint64			start_time	= 18;
 }
 
 message task_core_entry {
@@ -79,6 +80,7 @@ message task_core_entry {
 	repeated sa_entry		sigactions	= 15;
 	optional int32			tty_nr		= 16;
 	optional int32			tty_pgrp	= 17;
+	optional uint64			start_time	= 18;
 }
 
 message task_kobj_ids_entry {
-- 
1.8.3.1