[PATCH 37] introduce ptrace_event->ev_options

[Oleg Nesterov]

When the tracee resumes from TASK_TRACED, context->options can be changed.

Introduce ptrace_event->ev_options. If a callback sets ->ev_options != 0,
do_ptrace_resume() checks that context->options matches or discards the
event.

This will be used to validate PTRACE_EVENT_VFORK_DONE and SYSCALL_EXIT
reports.

---

 kernel/ptrace.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

--- PU/kernel/ptrace.c~37_EV_OPTIONS    2009-09-15 18:05:42.000000000 +0200
+++ PU/kernel/ptrace.c  2009-09-15 18:06:53.000000000 +0200
@@ -31,6 +31,8 @@ struct ptrace_event {
        int             ev_code;
        unsigned long   ev_message;
        resume_func_t   ev_resume;
+
+       int             ev_options;
 };
 
 struct ptrace_context {
@@ -1007,9 +1009,13 @@ static void do_ptrace_resume(struct utra
                if (ev->ev_resume)
                        ev->ev_resume(engine, tracee, data);
 
-               if (!ev_empty(context)) {
-                       do_ptrace_notify_stop(context, tracee);
-                       return;
+               while (!ev_empty(context)) {
+                       int ev_o = ev_current(context)->ev_options;
+                       if (!ev_o || (ev_o & context->options)) {
+                               do_ptrace_notify_stop(context, tracee);
+                               return;
+                       }
+                       ev_pop(context);
                }
        }