ptrace children revamp
ptrace no longer fiddles with the children/sibling links, and the
old ptrace_children list is gone. Now ptrace, whether of one's own
children or another's via PTRACE_ATTACH, just uses the new ptraced
list instead.
There should be no user-visible difference that matters. The only
change is the order in which do_wait() sees multiple stopped
children and stopped ptrace attachees. Since wait_task_stopped()
was changed earlier so it no longer reorders the children list, we
already know this won't cause any new problems.
Signed-off-by: Roland McGrath <roland@redhat.com>
diff --git a/include/linux/sched.h b/include/linux/sched.h
index ba2f859..1941d8b 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1062,12 +1062,6 @@
#endif
struct list_head tasks;
- /*
- * ptrace_list/ptrace_children forms the list of my children
- * that were stolen by a ptracer.
- */
- struct list_head ptrace_children;
- struct list_head ptrace_list;
struct mm_struct *mm, *active_mm;
@@ -1089,18 +1083,25 @@
/*
* pointers to (original) parent process, youngest child, younger sibling,
* older sibling, respectively. (p->father can be replaced with
- * p->parent->pid)
+ * p->real_parent->pid)
*/
- struct task_struct *real_parent; /* real parent process (when being debugged) */
- struct task_struct *parent; /* parent process */
+ struct task_struct *real_parent; /* real parent process */
+ struct task_struct *parent; /* recipient of SIGCHLD, wait4() reports */
/*
- * children/sibling forms the list of my children plus the
- * tasks I'm ptracing.
+ * children/sibling forms the list of my natural children
*/
struct list_head children; /* list of my children */
struct list_head sibling; /* linkage in my parent's children list */
struct task_struct *group_leader; /* threadgroup leader */
+ /*
+ * ptraced is the list of tasks this task is using ptrace on.
+ * This includes both natural children and PTRACE_ATTACH targets.
+ * p->ptrace_entry is p's link on the p->parent->ptraced list.
+ */
+ struct list_head ptraced;
+ struct list_head ptrace_entry;
+
/* PID/PID hash table linkage. */
struct pid_link pids[PIDTYPE_MAX];
struct list_head thread_group;
@@ -1876,9 +1877,6 @@
#define wait_task_inactive(p) do { } while (0)
#endif
-#define remove_parent(p) list_del_init(&(p)->sibling)
-#define add_parent(p) list_add_tail(&(p)->sibling,&(p)->parent->children)
-
#define next_task(p) list_entry(rcu_dereference((p)->tasks.next), struct task_struct, tasks)
#define for_each_process(p) \