[CRIU] [PATCH] pstree: Do not populate zero levels of task's pid

[Kirill Tkhai]

If task's pid were hashed before the task itself
(this may happen, when another task has sid or pgid
equal to this pid), the pid mustn't contain zero
levels. So, if pgid or sid has zero levels, we should
not add them.

Otherwise, session04 --iter 3 fails with:

=[log]=> dump/zdtm/static/session04/30/2/restore.log
------------------------ grep Error ------------------------
(01.858187)      6: Restoring children in our session:
(01.858206)      6: Forking task with 303 pid (flags 0x600)
(01.869893)      1: PID: real 145 virt 15
(01.870247)      1: Forking task with 20 pid (flags 0x0)
(01.872948) Error (criu/cr-restore.c:381): 0: Write -1 to sys/kernel/ns_last_pid: Invalid argument
(01.873030) Error (criu/namespaces.c:2664): Can't set next pid
(01.873103)      1: Error (criu/ns-common.c:46): Error answer
(01.873123)      1: Error (criu/cr-restore.c:404): Can't request next pid
(01.873135)      1: Error (criu/cr-restore.c:1321): Can't set next pid
(01.873310)      1: Error (criu/cr-restore.c:1434): Can't fork for 20: No such file or directory

Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
---
 criu/pstree.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/criu/pstree.c b/criu/pstree.c
index 9ae191292..c211c1492 100644
--- a/criu/pstree.c
+++ b/criu/pstree.c
@@ -533,9 +533,9 @@ static struct pid *find_pid_or_place_in_hier(struct rb_node **root, pid_t pid, i
 static struct pid *lookup_create_pid(pid_t *pid, int level, struct pid *pid_node, int ns_id)
 {
 	struct rb_node **new = NULL, *parent = NULL;
-	int i, orig_level = level;
 	struct pid *found;
 	struct ns_id *ns;
+	int i;
 
 	ns = lookup_ns_by_id(ns_id, &pid_ns_desc);
 
@@ -561,11 +561,11 @@ static struct pid *lookup_create_pid(pid_t *pid, int level, struct pid *pid_node
 	if (!pid_node) {
 		struct pstree_item *item;
 
-		item = __alloc_pstree_item(true, orig_level);
+		item = __alloc_pstree_item(true, level);
 		if (item == NULL)
 			return NULL;
 
-		for (i = 0; i < orig_level; i++)
+		for (i = 0; i < level; i++)
 			item->pid->ns[i].virt = pid[i];
 		pid_node = item->pid;
 	}