[PATCH 7/9] ptrace: Simplify the wait_task_inactive call in ptrace_check_attach

[Oleg Nesterov]

On 04/26, Eric W. Biederman wrote:
>
> Asking wait_task_inactive to verify that tsk->__state == __TASK_TRACED
> was needed to detect the when ptrace_stop would decide not to stop
> after calling "set_special_state(TASK_TRACED)".  With the recent
> cleanups ptrace_stop will always stop after calling set_special_state.
>
> Take advatnage of this by no longer asking wait_task_inactive to
> verify the state.  If a bug is hit and wait_task_inactive does not
> succeed warn and return -ESRCH.

ACK, but I think that the changelog is wrong.

We could do this right after may_ptrace_stop() has gone. This doesn't
depend on the previous changes in this series.

Oleg.