dump: Switch to /proc/$pid/children parsing to obtain children set

This also depends on kernel's inteface being changed,
so kernel/ is updated as well.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>

cr-dump.c

@@ -727,6 +727,23 @@ static struct pstree_item *find_pstree_entry(pid_t pid)
 
 	pr_debug("pid: %d\n", pid);
 
+	file = fopen_proc("%d/children", "r", pid);
+	if (!file) {
+		pr_perror("Can't open %d children", pid);
+		goto err;
+	}
+
+	if (!(fgets(loc_buf, sizeof(loc_buf), file))) {
+		pr_perror("Can't read %d children content", pid);
+		goto err;
+	}
+
+	children_str = xstrdup(loc_buf);
+	if (!children_str)
+		goto err;
+
+	fclose(file), file = NULL;
+
 	file = fopen_proc("%d/status", "r", pid);
 	if (!file) {
 		pr_perror("Can't open %d status", pid);
@@ -734,13 +751,7 @@ static struct pstree_item *find_pstree_entry(pid_t pid)
 	}
 
 	while ((fgets(loc_buf, sizeof(loc_buf), file))) {
-		if (!strncmp(loc_buf, "Children:", 9)) {
-			children_str = xstrdup(&loc_buf[10]);
-			if (!children_str)
-				goto err;
-			if (nr_threads)
-				break;
-		} else if (!strncmp(loc_buf, "Threads:", 8)) {
+		if (!strncmp(loc_buf, "Threads:", 8)) {
 			nr_threads = atoi(&loc_buf[9]);
 			if (children_str)
 				break;
@@ -790,6 +801,8 @@ static struct pstree_item *find_pstree_entry(pid_t pid)
 	item->threads		= threads;
 
 err:
+	if (file)
+		fclose(file);
 	xfree(children_str);
 	return item;
 

kernel/fs-proc-Introduce-the-Children-line-in-proc-pid-stat

-fs, proc: Introduce the Children: line in /proc/<pid>/status
-
-From: Pavel Emelyanov <xemul@parallels.com>
-
-There is no easy way to make a reverse parent->children chain
-from the task status, in turn children->parent provided with "PPid"
-field.
-
-So instead of walking over all pids in system to figure out what
-children the task have -- we add explicit "Children" member to
-/proc/<pid>/status since kernel already knows this kind of information
-but it was not yet exported.
-
-Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
-Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
-Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
----
- fs/proc/array.c |   14 ++++++++++++++
- 1 files changed, 14 insertions(+), 0 deletions(-)
-
---- a/fs/proc/array.c
-+++ b/fs/proc/array.c
-@@ -158,6 +158,18 @@ static inline const char *get_task_state(struct task_struct *tsk)
- 	return *p;
- }
- 
-+static void task_children(struct seq_file *m, struct task_struct *p, struct pid_namespace *ns)
-+{
-+	struct task_struct *c;
-+
-+	seq_printf(m, "Children:");
-+	read_lock(&tasklist_lock);
-+	list_for_each_entry(c, &p->children, sibling)
-+		seq_printf(m, " %d", pid_nr_ns(task_pid(c), ns));
-+	read_unlock(&tasklist_lock);
-+	seq_putc(m, '\n');
-+}
-+
- static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
- 				struct pid *pid, struct task_struct *p)
- {
-@@ -192,6 +204,8 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
- 		cred->uid, cred->euid, cred->suid, cred->fsuid,
- 		cred->gid, cred->egid, cred->sgid, cred->fsgid);
- 
-+	task_children(m, p, ns);
-+
- 	task_lock(p);
- 	if (p->files)
- 		fdt = files_fdtable(p->files);
--- 
-1.7.7.3
-

kernel/fs-proc-add-children-entry

+fs, proc: Introduce the /proc/<pid>/children entry
+
+There is no easy way to make a reverse parent->children chain
+from the task status, in turn children->parent provided with "PPid"
+field.
+
+So instead of walking over all pids in system to figure out what
+children the task have -- we add explicit /proc/<pid>/children entry,
+since kernel already knows this kind of information but it was not
+yet exported.
+
+Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
+Cc: Pavel Emelyanov <xemul@parallels.com>
+Cc: Serge Hallyn <serge.hallyn@canonical.com>
+Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
+---
+ fs/proc/array.c    |   14 ++++++++++++++
+ fs/proc/base.c     |    1 +
+ fs/proc/internal.h |    3 +++
+ 3 files changed, 18 insertions(+)
+
+Index: linux-2.6.git/fs/proc/array.c
+===================================================================
+--- linux-2.6.git.orig/fs/proc/array.c
++++ linux-2.6.git/fs/proc/array.c
+@@ -547,3 +547,17 @@ int proc_pid_statm(struct seq_file *m, s
+ 
+ 	return 0;
+ }
++
++int proc_pid_children(struct seq_file *m, struct pid_namespace *ns,
++		      struct pid *pid, struct task_struct *task)
++{
++	struct task_struct *c;
++
++	read_lock(&tasklist_lock);
++	list_for_each_entry(c, &task->children, sibling)
++		seq_printf(m, " %d", pid_nr_ns(task_pid(c), ns));
++	read_unlock(&tasklist_lock);
++	seq_putc(m, '\n');
++
++	return 0;
++}
+Index: linux-2.6.git/fs/proc/base.c
+===================================================================
+--- linux-2.6.git.orig/fs/proc/base.c
++++ linux-2.6.git/fs/proc/base.c
+@@ -3204,6 +3204,7 @@ static const struct pid_entry tgid_base_
+ 	INF("cmdline",    S_IRUGO, proc_pid_cmdline),
+ 	ONE("stat",       S_IRUGO, proc_tgid_stat),
+ 	ONE("statm",      S_IRUGO, proc_pid_statm),
++	ONE("children",   S_IRUGO, proc_pid_children),
+ 	REG("maps",       S_IRUGO, proc_maps_operations),
+ #ifdef CONFIG_NUMA
+ 	REG("numa_maps",  S_IRUGO, proc_numa_maps_operations),
+Index: linux-2.6.git/fs/proc/internal.h
+===================================================================
+--- linux-2.6.git.orig/fs/proc/internal.h
++++ linux-2.6.git/fs/proc/internal.h
+@@ -51,6 +51,9 @@ extern int proc_pid_status(struct seq_fi
+ 				struct pid *pid, struct task_struct *task);
+ extern int proc_pid_statm(struct seq_file *m, struct pid_namespace *ns,
+ 				struct pid *pid, struct task_struct *task);
++extern int proc_pid_children(struct seq_file *m, struct pid_namespace *ns,
++			     struct pid *pid, struct task_struct *task);
++
+ extern loff_t mem_lseek(struct file *file, loff_t offset, int orig);
+ 
+ extern const struct file_operations proc_maps_operations;

kernel/series

@@ -3,7 +3,7 @@ fs-proc-Introduce-the-proc-pid-map_files-directory
 procfs-introduce-the-proc-pid-map_files-directory-checkpatch
 clone-Introduce-the-CLONE_CHILD_USEPID-functionality
 fs-proc-Add-start_data-end_data-start_brk-members
-fs-proc-Introduce-the-Children-line-in-proc-pid-stat
+fs-proc-add-children-entry
 prctl-tune-up-mm_struct-members-2
 mincore-Add-named-constant-for-reported-present-bit
 mincore-Report-whether-page-is-anon-or-not