[haiku-development] Re: address space rwlock issue?
- From: David McPaul <dlmcpaul@xxxxxxxxx>
- To: haiku-development@xxxxxxxxxxxxx
- Date: Mon, 16 Mar 2009 10:32:50 +1100
On 2009-03-16, Ingo Weinhold <ingo_weinhold@xxxxxx> wrote:
>
> On 2009-03-15 at 20:08:56 [+0100], Jonas Sundström <jonas@xxxxxxxxxxx>
> wrote:
> > Ingo Weinhold <ingo_weinhold@xxxxxx> wrote:
> > ...
> > > it is not always known
> > > which thread is holding a lock.
> >
> > If the kernel doesn´t know, how can locks work
> > reliably, let alone be released when processes exit?
>
> Kernelland is a very controlled environment. Only kernel (proper) and
> driver code is executed and that code has certain responsibilities. If a
> function acquires a lock, it is also responsible for releasing it,
> respectively there's a well-defined strategy how the lock is released (e.g.
> some other called function does).
>
> There's only one point where a userland thread can die (regardless whether
> it was caused by {exit,kill}_thread() or whatever), which is in the kernel
> right before the thread would return to userland. At this point no kernel
> locks are held. Kernel threads can only exit explicitly (via exit_thread())
> and it is the responsibility of that thread/code that no further kernel
> locks are held at that time.
Is there a document I can read about debugging locks?
Because I can lock up MediaPlayer quite easily to the point where only
a reboot fixes it.
--
Cheers
David
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