ptrace: reintroduce __ptrace_detach() as a callee of ptrace_exit()

No functional changes, preparation for the next patch.

Move the "should we release this child" logic into the separate handler,
__ptrace_detach().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 33 insertions, 29 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 7a8311422930..576eae233b53 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -744,6 +744,38 @@ static int ignoring_children(struct sighand_struct *sigh)
         return ret;
 }
 
+/* Returns nonzero if the tracee should be released. */
+int __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
+{
+        __ptrace_unlink(p);
+
+        if (p->exit_state != EXIT_ZOMBIE)
+                return 0;
+        /*
+         * If it's a zombie, our attachedness prevented normal
+         * parent notification or self-reaping.  Do notification
+         * now if it would have happened earlier.  If it should
+         * reap itself we return true.
+         *
+         * If it's our own child, there is no notification to do.
+         * But if our normal children self-reap, then this child
+         * was prevented by ptrace and we must reap it now.
+         */
+        if (!task_detached(p) && thread_group_empty(p)) {
+                if (!same_thread_group(p->real_parent, tracer))
+                        do_notify_parent(p, p->exit_signal);
+                else if (ignoring_children(tracer->sighand))
+                        p->exit_signal = -1;
+        }
+
+        if (!task_detached(p))
+                return 0;
+
+        /* Mark it as in the process of being reaped. */
+        p->exit_state = EXIT_DEAD;
+        return 1;
+}
+
 /*
  * Detach all tasks we were using ptrace on.
  * Any that need to be release_task'd are put on the @dead list.
@@ -755,36 +787,8 @@ static void ptrace_exit(struct task_struct *parent, struct list_head *dead)
         struct task_struct *p, *n;
 
         list_for_each_entry_safe(p, n, &parent->ptraced, ptrace_entry) {
-                __ptrace_unlink(p);
-
-                if (p->exit_state != EXIT_ZOMBIE)
-                        continue;
-
-                /*
-                 * If it's a zombie, our attachedness prevented normal
-                 * parent notification or self-reaping.  Do notification
-                 * now if it would have happened earlier.  If it should
-                 * reap itself, add it to the @dead list.  We can't call
-                 * release_task() here because we already hold tasklist_lock.
-                 *
-                 * If it's our own child, there is no notification to do.
-                 * But if our normal children self-reap, then this child
-                 * was prevented by ptrace and we must reap it now.
-                 */
-                if (!task_detached(p) && thread_group_empty(p)) {
-                        if (!same_thread_group(p->real_parent, parent))
-                                do_notify_parent(p, p->exit_signal);
-                        else if (ignoring_children(parent->sighand))
-                                p->exit_signal = -1;
-                }
-
-                if (task_detached(p)) {
-                        /*
-                         * Mark it as in the process of being reaped.
-                         */
-                        p->exit_state = EXIT_DEAD;
+                if (__ptrace_detach(parent, p))
                         list_add(&p->ptrace_entry, dead);
-                }
         }
 }