Davide Libenzi wrote: > On Fri, 24 Apr 2009, Gregory Haskins wrote: > > >> Davide Libenzi wrote: >> >>> On Thu, 23 Apr 2009, Gregory Haskins wrote: >>> >>> >>> >>>>> Take a look at init_waitqueue_func_entry(), in particula at that "func" >>>>> parameter. Then look at how __wake_up_common() does its thing. >>>>> You don't need to be "waiting" for our wakeup system to work. Callbacks >>>>> works just fine, otherwise things like epoll could not work at all. >>>>> >>>>> >>>>> >>>> Yeah, I was looking at that this afternoon after you mentioned it. That >>>> makes sense. >>>> >>>> As of right now the wqh is embedded in the eventfd, accessible only by >>>> the .read() vtable entry. In order to do this as you suggest, I imagine >>>> I need to slightly modify the eventfd interface to allow waiters other >>>> than the embedded readers to join the wait-queue. How would you like to >>>> see that interface look? >>>> >>>> >>> Actually, you need no changes in eventfd, since you can use its poll() >>> directly, by dropping a callback entry. >>> Take a look at how epoll does it in ep_insert()... >>> >>> >> Ah! I just tried your suggestion and it was simple and it works. That >> is brilliant. >> >> I will post a follow-up v2 that drops patch 2/3. Thanks, Davide. >> > > I assume you're in control of the file/fd lifetime, so that the file* > cannot vanish while you've your wait_queue dropped inside its > wait_queue_head, isn't it? > I've addressed this issue by holding the file via eventfd_fget(), but your review to make sure I got it right would be appreciated. -Greg
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