ptrace_attach_task:
engine = utrace_attach_task(CREATE | EXCLUSIVE);
err = utrace_set_events();
WARN_ON(err && !tracee->exit_state);
Looks correct but it is not. utrace_attach_task() can return EINPROGRESS.
Note that start_callback/etc sets ->reporting = engine even if we are not
going to call ->report_any(). I'll try to think, perhaps we can change this
code to check engine->flags first...
Note that EINPROGRESS can happen even if there are no other tracers.
utrace_add_engine() sets ->report and the tracee can call utrace_resume()
before we do utrace_set_events().
I think that it makes sense to check utrace_flags & QUIESCE in utrace_resume()
and return if it is not set. But even with this change EINPROGRESS is still
possible if we have other engines.
But the real problem is, _sometimes_ "make xcheck" triggers this warning,
and I can not understand:
1. Why I didn't see it before context->options was added
2. I changed utrace_resume() to check QUIESCE. But I still
see the warning!
Still investigating...
---
kernel/ptrace.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- PU/kernel/ptrace.c~23_ATTACH_KILL_WARNING 2009-09-04 19:50:35.000000000
+0200
+++ PU/kernel/ptrace.c 2009-09-04 19:57:47.000000000 +0200
@@ -505,8 +505,7 @@ static int ptrace_attach_task(struct tas
* It can fail only if the tracee is dead, the caller
* must notice this before setting PT_PTRACED.
*/
- err = __ptrace_set_options(tracee, engine, options);
- WARN_ON(err && !tracee->exit_state);
+ __ptrace_set_options(tracee, engine, options);
utrace_engine_put(engine);
return 0;
}
