Messages in this thread | | | From | David Howells <> | Subject | Re: [PATCH v4 2/3] genirq: reimplement exit_irq_thread() hook via task_work_add() | Date | Tue, 17 Apr 2012 15:11:18 +0100 |
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Oleg Nesterov <oleg@redhat.com> wrote:
> 2. change irq_thread() to do task_queue_work(irq_thread_dtor) > at the start and task_work_cancel() before return. > > tracehook_notify_resume() can never play with kthreads, > only do_exit()->exit_task_work() can call the callback > and this is what we want.
Hmmm... This seems wrong. You're now using the hook in two distinct ways: the primary use of that the hook is to detect that userspace is about to resume processing (via TIF_NOTIFY_RESUME) and then you're abusing the fact that the hook is also invoked via do_exit() to perform a clean up because we've got to get rid of it somehow under that circumstance.
This only works for you because you're operating in a kernel thread which doesn't have a userspace (and so will never see TIF_NOTIFY_RESUME). However, if someone tries that in an ordinary thread, it is liable to malfunction as the record could be executed and deleted at some unpredictable point in the future.
David
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