From: John Levon <movement@marcelothewonderpenguin.com>
To: linux-kernel@vger.kernel.org
Subject: Re: Sleeping function called from illegal context...
Date: Sat, 28 Sep 2002 18:24:50 +0100 [thread overview]
Message-ID: <20020928172449.GA54680@compsoc.man.ac.uk> (raw)
In-Reply-To: <3D95E14D.9134405C@digeo.com>
On Sat, Sep 28, 2002 at 10:05:17AM -0700, Andrew Morton wrote:
> We need a standalone CONFIG_MIGHT_SLEEP. I sinfully hooked it
> to CONFIG_DEBUG_KERNEL (it's not obvious why CONFIG_DEBUG_KERNEL
> exists actually).
Ah, OK.
> > I have a bit of a problem with __might_sleep because I call sleepable
> > stuff holding a spinlock (yes, it is justified, and yes, it is safe
> > afaics, at least with PREEMPT=n)
>
> I'm looking at you suspiciously. How come?
NMI interrupt handler cannot block so it trylocks against a spinlock
instead. Buffer processing code needs to block against concurrent NMI
interrupts so takes the spinlock for them. All actual blocks on the
spinlock are beneath a down() on another semaphore, so a sleep whilst
holding the spinlock won't actually cause deadlock.
I don't know a way out of this that can safely ensure we've finished
processing an NMI on the remote CPU the buffer processing code is about
to look at.
[I'll post a new patch against 2.5.39 in a bit so you can see in
context]
regards
john
--
"When your name is Winner, that's it. You don't need a nickname."
- Loser Lane
next prev parent reply other threads:[~2002-09-28 17:19 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-27 23:30 Sleeping function called from illegal context Greg KH
2002-09-27 23:50 ` Andrew Morton
2002-09-28 0:43 ` (more) " Luc Van Oostenryck
2002-09-28 1:22 ` Andrew Morton
2002-09-28 0:44 ` Luc Van Oostenryck
2002-09-28 1:24 ` Andrew Morton
2002-09-28 2:15 ` Greg KH
2002-09-28 0:44 ` Luc Van Oostenryck
2002-09-28 1:27 ` Andrew Morton
2002-09-30 12:50 ` [Lksctp-developers] " Jon Grimm
2002-09-30 13:34 ` Jon Grimm
2002-09-28 2:04 ` Andre Hedrick
2002-09-28 3:06 ` Robert Love
2002-09-28 3:21 ` Andre Hedrick
2002-09-28 3:29 ` Robert Love
2002-09-28 10:06 ` Alan Cox
2002-09-28 17:06 ` Robert Love
2002-09-28 0:51 ` Robert Love
2002-09-28 2:16 ` Greg KH
2002-09-28 14:54 ` John Levon
2002-09-28 17:05 ` Andrew Morton
2002-09-28 17:24 ` John Levon [this message]
2002-09-28 18:27 ` Robert Love
2002-09-28 18:38 ` John Levon
2002-09-29 0:50 ` William Lee Irwin III
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20020928172449.GA54680@compsoc.man.ac.uk \
--to=movement@marcelothewonderpenguin.com \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).