From: Jon Smirl <jonsmirl@yahoo.com>
To: Andrew Morton <akpm@osdl.org>
Cc: linux-kernel@vger.kernel.org, keithp@keithp.com
Subject: Re: Is it possible to implement interrupt time printk's reliably?
Date: Fri, 7 May 2004 06:34:03 -0700 (PDT) [thread overview]
Message-ID: <20040507133403.39224.qmail@web14923.mail.yahoo.com> (raw)
In-Reply-To: <20040506221746.7bb45421.akpm@osdl.org>
--- Andrew Morton <akpm@osdl.org> wrote:
> Jon Smirl <jonsmirl@yahoo.com> wrote:
> >
> > Problem:
> > 1) Some operations on graphics cards cannot be stopped once they are
> started.
> > It's not reasonable to turn interrupts off around these operations.
> > 2) Kernel developers want console printk's to work from interrupt routines.
> >
> > How do you fix this situation?
>
> Really you should use spin_lock_irqsave() on some driver-private lock
> around the operation. Why is it not reasonable to disable irq's?
> Duration, presumably?
The operations take a while and would ruin latency. You might be copying 8MB of
data.
> If you're in process context you can use acquire_console_sem(), which will
> serialise against printk.
>
Won't I deadlock if I have acquire_console_sem(), take an interrupt, and then a
printk is issued from the interrupt handelr?
=====
Jon Smirl
jonsmirl@yahoo.com
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next prev parent reply other threads:[~2004-05-07 13:34 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-05-07 2:52 Jon Smirl
2004-05-07 5:17 ` Andrew Morton
2004-05-07 13:34 ` Jon Smirl [this message]
2004-05-07 19:13 ` Andrew Morton
2004-05-07 19:26 ` Jon Smirl
2004-05-07 20:01 ` Andrew Morton
2004-05-09 16:33 ` Jon Smirl
2004-05-10 21:55 ` James Simmons
2004-05-10 22:22 ` Jon Smirl
2004-05-11 0:23 ` James Simmons
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