1 files changed, 88 insertions, 15 deletions

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index c9cf48b21f05..aaad0ec34194 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -60,11 +60,15 @@ static void ptrace_untrace(struct task_struct *child)
 {
         spin_lock(&child->sighand->siglock);
         if (task_is_traced(child)) {
-                if (child->signal->flags & SIGNAL_STOP_STOPPED) {
+                /*
+                 * If the group stop is completed or in progress,
+                 * this thread was already counted as stopped.
+                 */
+                if (child->signal->flags & SIGNAL_STOP_STOPPED ||
+                    child->signal->group_stop_count)
                         __set_task_state(child, TASK_STOPPED);
-                } else {
+                else
                         signal_wake_up(child, 1);
-                }
         }
         spin_unlock(&child->sighand->siglock);
 }
@@ -235,18 +239,58 @@ out:
         return retval;
 }
 
-static inline void __ptrace_detach(struct task_struct *child, unsigned int data)
+/*
+ * Called with irqs disabled, returns true if childs should reap themselves.
+ */
+static int ignoring_children(struct sighand_struct *sigh)
 {
-        child->exit_code = data;
-        /* .. re-parent .. */
-        __ptrace_unlink(child);
-        /* .. and wake it up. */
-        if (child->exit_state != EXIT_ZOMBIE)
-                wake_up_process(child);
+        int ret;
+        spin_lock(&sigh->siglock);
+        ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
+              (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
+        spin_unlock(&sigh->siglock);
+        return ret;
+}
+
+/*
+ * Called with tasklist_lock held for writing.
+ * Unlink a traced task, and clean it up if it was a traced zombie.
+ * Return true if it needs to be reaped with release_task().
+ * (We can't call release_task() here because we already hold tasklist_lock.)
+ *
+ * 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, 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.
+ */
+static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
+{
+        __ptrace_unlink(p);
+
+        if (p->exit_state == EXIT_ZOMBIE) {
+                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)) {
+                        /* Mark it as in the process of being reaped. */
+                        p->exit_state = EXIT_DEAD;
+                        return true;
+                }
+        }
+
+        return false;
 }
 
 int ptrace_detach(struct task_struct *child, unsigned int data)
 {
+        bool dead = false;
+
         if (!valid_signal(data))
                 return -EIO;
 
@@ -255,14 +299,45 @@ int ptrace_detach(struct task_struct *child, unsigned int data)
         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 
         write_lock_irq(&tasklist_lock);
-        /* protect against de_thread()->release_task() */
-        if (child->ptrace)
-                __ptrace_detach(child, data);
+        /*
+         * This child can be already killed. Make sure de_thread() or
+         * our sub-thread doing do_wait() didn't do release_task() yet.
+         */
+        if (child->ptrace) {
+                child->exit_code = data;
+                dead = __ptrace_detach(current, child);
+        }
         write_unlock_irq(&tasklist_lock);
 
+        if (unlikely(dead))
+                release_task(child);
+
         return 0;
 }
 
+/*
+ * Detach all tasks we were using ptrace on.
+ */
+void exit_ptrace(struct task_struct *tracer)
+{
+        struct task_struct *p, *n;
+        LIST_HEAD(ptrace_dead);
+
+        write_lock_irq(&tasklist_lock);
+        list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
+                if (__ptrace_detach(tracer, p))
+                        list_add(&p->ptrace_entry, &ptrace_dead);
+        }
+        write_unlock_irq(&tasklist_lock);
+
+        BUG_ON(!list_empty(&tracer->ptraced));
+
+        list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
+                list_del_init(&p->ptrace_entry);
+                release_task(p);
+        }
+}
+
 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
 {
         int copied = 0;
@@ -612,8 +687,6 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, long, addr, long, data)
                 goto out_put_task_struct;
 
         ret = arch_ptrace(child, request, addr, data);
-        if (ret < 0)
-                goto out_put_task_struct;
 
  out_put_task_struct:
         put_task_struct(child);