Messages in this thread | | | Date | Mon, 25 Nov 2002 15:19:30 -0800 (PST) | From | Davide Libenzi <> | Subject | Re: [rfc] new poll callback'd wake up hell ... |
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On Mon, 25 Nov 2002, John Myers wrote:
> Davide Libenzi wrote: > > >No, look at the code : > > > > > Ok, I completely misread what you wrote. I thought you were suggestiong > a change to the locking behavior of wake_up() itself.
The problem with the wake_up() is its potential recursion when using the callback'd version of the wait queue. We can have two scenarios ( given '->' == CONTAINED-IN ) :
1) epfd1 -> epfd2 -> ... ->epfdN with N huge
2) epfd1 -> epfd2 -> ... -> epfd1
Now, when you call wake_up() without using any care you'll blow up the stack. This should be adressed with the 0.58 version of the patch. Also, I moved the :
/* Add the current item to the list of active epoll hook for this file */ spin_lock(&tfile->f_ep_lock); list_add_tail(&epi->fllink, &tfile->f_ep_links); spin_unlock(&tfile->f_ep_lock);
before inserting the item in the hash, so I don't need to increase the usage count in ep_insert().
- Davide
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