pstree: Add task_st bit field

(was "files: Wait transport_fd before sending a fd to peer"
and "pstree: Add task_st futex")

We are going to move to the the single per-task bit field
for notifications about file opening events. Introduce
pstree_item::task_st for that.

v5: Add FDS_EVENT_BIT description.

v2: Do not wait until a peer's socket is created
as it's guarantied by we create it before CR_STATE_FORKING.

travis-ci: success for Rework file opening scheme to make it asynchronous (rev5)
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/include/pstree.h

@@ -2,6 +2,7 @@
 #define __CR_PSTREE_H__
 
 #include "common/list.h"
+#include "common/lock.h"
 #include "pid.h"
 #include "images/core.pb-c.h"
 
@@ -24,8 +25,14 @@ struct pstree_item {
 	struct pid		*threads;	/* array of threads */
 	CoreEntry		**core;
 	TaskKobjIdsEntry	*ids;
+	futex_t			task_st;
 };
 
+enum {
+	FDS_EVENT_BIT	= 0,
+};
+#define FDS_EVENT (1 << FDS_EVENT_BIT)
+
 struct pstree_item *current;
 
 struct rst_info;

criu/pstree.c

@@ -219,6 +219,7 @@ struct pstree_item *__alloc_pstree_item(bool rst)
 	item->pid->real = -1;
 	item->born_sid = -1;
 	item->pid->item = item;
+	futex_init(&item->task_st);
 
 	return item;
 }