From owner-freebsd-hackers  Mon Aug 26 10:14:38 2002
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Date: Mon, 26 Aug 2002 10:14:32 -0700
From: Maksim Yevmenkin <myevmenk@exodus.net>
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To: Bosko Milekic <bmilekic@unixdaemons.com>
Cc: John Baldwin <jhb@FreeBSD.ORG>,
	"M. Warner Losh" <imp@bsdimp.com>, hackers@FreeBSD.ORG
Subject: Re: Fast interrupts
References: <XFMail.20020826112635.jhb@FreeBSD.org> <3D6A5A47.57672729@exodus.net> <20020826130611.A48166@unixdaemons.com>
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Bosko Milekic wrote:
> 
> On Mon, Aug 26, 2002 at 09:41:43AM -0700, Maksim Yevmenkin wrote:
> > John Baldwin wrote:
> > >
> > > On 26-Aug-2002 M. Warner Losh wrote:
> > > > can you call wakeup(9) from a fast interrupt handler?
> >
> > [ ...]
> >
> > > > The only reason I ask is because sio seems to go out of its way to
> > > > schedule a soft interrupt to deal with waking up processes, which then
> > > > calls wakeup...
> > >
> > > Since wakeup only needs a spin lock, it is probably ok.  You just can't call
> > > anything that would sleep (in any interrupt handler) or block on a non-spin
                                ^^^^^^^^^^^^^^^^^^^^^^^^^^
my understanding is that John was talking about any
interrupt handler. Not just fast interrupt hander.

> > > mutex.
> >
> > what is the general locking technique for interrupt handlers?
> > there must be some sort of locking, right?
> 
>   You are allowed to use mutex locks (both spin and MTX_DEF), only you
>   are only allowed to user the former for fast interrupt handlers.

thanks,
max

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