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authorOleg Nesterov <oleg@redhat.com>2017-01-30 18:06:11 +0300
committerEric W. Biederman <ebiederm@xmission.com>2017-02-03 16:34:41 +1300
commit0f1b92cbdd0309afae0af1963e8cccddb3d2eaff (patch)
treef30ecfd58043e4a2b32de2b053efac37a4f03b21 /kernel/fork.c
parent015bb305b8ebe8d601a238ab70ebdc394c7a19ba (diff)
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introduce the walk_process_tree() helper
Add the new helper to walk the process tree, the next patch adds a user. Note that it visits the group leaders only, proc_visitor can do for_each_thread itself or we can trivially extend walk_process_tree() to do this. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'kernel/fork.c')
-rw-r--r--kernel/fork.c32
1 files changed, 32 insertions, 0 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 11c5c8ab827c..135b7a49ad59 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2053,6 +2053,38 @@ SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
}
#endif
+void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data)
+{
+ struct task_struct *leader, *parent, *child;
+ int res;
+
+ read_lock(&tasklist_lock);
+ leader = top = top->group_leader;
+down:
+ for_each_thread(leader, parent) {
+ list_for_each_entry(child, &parent->children, sibling) {
+ res = visitor(child, data);
+ if (res) {
+ if (res < 0)
+ goto out;
+ leader = child;
+ goto down;
+ }
+up:
+ ;
+ }
+ }
+
+ if (leader != top) {
+ child = leader;
+ parent = child->real_parent;
+ leader = parent->group_leader;
+ goto up;
+ }
+out:
+ read_unlock(&tasklist_lock);
+}
+
#ifndef ARCH_MIN_MMSTRUCT_ALIGN
#define ARCH_MIN_MMSTRUCT_ALIGN 0
#endif