Re: PR/45909: Use of MIDI over USB interfaces crashes NetBSD

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Sat, Feb 04, 2012 at 02:50:04PM +0000, Tom Ivar Helbekkmo wrote:
>  Yeah, I don't understand that bit at all.  You get a KASSERT failure if
>  you call usbd_abort_pipe() without holding the kernel lock, though - and
>  another one if you *are* holding the thread lock, when it tries to do a
>  context change with a mutex held.  This challenges my understanding of
>  what the kernel lock is.  :)

the kernel lock is much more than a simple mutex (there's a refcount so
it can be reentrant, for example). When the kernel is going to sleep,
the kernel lock is released and reaquired on wakeup.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
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