From: george anzinger <george@mvista.com>
To: Oliver Neukum <oliver@neukum.name>
Cc: Thunder from the hill <thunder@lightweight.ods.org>,
Ralf Baechle <ralf@uni-koblenz.de>,
linux-kernel@vger.kernel.org
Subject: Re: question on spinlocks
Date: Tue, 03 Sep 2002 15:13:09 -0700 [thread overview]
Message-ID: <3D7533F5.F00BB8E6@mvista.com> (raw)
In-Reply-To: 200209020033.23113.oliver@neukum.name
Oliver Neukum wrote:
>
> Am Montag, 2. September 2002 00:09 schrieb Thunder from the hill:
> > Hi,
> >
> > On Mon, 2 Sep 2002, Oliver Neukum wrote:
> > > > > No; spin_lock_irqsave/spin_unlock_irqrestore and
> > > > > spin_lock/spin_unlock have to be used in matching pairs.
> > > >
> > > > If it was his least problem! He'll run straight into a "schedule
> > > > w/IRQs disabled" bug.
> > >
> > > OK, how do I drop an irqsave spinlock if I don't have flags?
> >
> > IMHO you might even ask "How do I start a car when I don't have the
> > keys?"
>
> Break off the lock, touch some cables ... ;-)
>
> > You might find a way, but it's not desired. Are you sure you want to
> > reschedule in an interrupt handler? If it's none, are you sure you want
> > to disable interrupts?
>
> I am not in an interrupt handler. It's not my fault that the scsi layer
> calls queuecommand with a spinlock held. But I need to sleep,
> I have to get rid of that spinlock's effects. If possible I even want
> interrupts to be enabled.
I don't know scsi, but if the coder decided that the lock
and irq were needed, I suspect that messing with them will
get you in big trouble. I think you need to rethink this
thing at the scsi layer...
-g
>
> Regards
> Oliver
>
> -
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--
George Anzinger george@mvista.com
High-res-timers:
http://sourceforge.net/projects/high-res-timers/
Preemption patch:
http://www.kernel.org/pub/linux/kernel/people/rml
next prev parent reply other threads:[~2002-09-03 22:09 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-01 17:27 question on spinlocks Oliver Neukum
2002-09-01 19:05 ` Ralf Baechle
2002-09-01 21:53 ` Thunder from the hill
2002-09-01 22:02 ` Oliver Neukum
2002-09-01 22:09 ` Thunder from the hill
2002-09-01 22:11 ` Robert Love
2002-09-01 22:33 ` Oliver Neukum
2002-09-02 22:30 ` Jan Hudec
2002-09-03 22:13 ` george anzinger [this message]
2002-09-01 22:11 ` Robert Love
2002-09-01 22:08 ` Robert Love
2002-09-01 22:16 ` Thunder from the hill
[not found] ` <mailman.1030918200.24262.linux-kernel2news@redhat.com>
2002-09-03 20:09 ` Pete Zaitcev
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