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ptrace children revamp

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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>
This commit is contained in:
Roland McGrath 2008-03-24 18:36:23 -07:00
commit f470021adb
5 changed files with 163 additions and 142 deletions
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26
include/linux/sched.h
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@ -1062,12 +1062,6 @@ struct task_struct {
#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 @@ struct task_struct {
/*
* 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 @@ extern void wait_task_inactive(struct task_struct * p);
#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) \