From: "Paul E. McKenney" <paulmck@us.ibm.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Dipankar Sarma <dipankar@in.ibm.com>,
Sven Dietrich <sdietrich@mvista.com>,
Daniel Walker <dwalker@mvista.com>, Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org, abatyrshin@ru.mvista.com,
amakarov@ru.mvista.com, emints@ru.mvista.com,
ext-rt-dev@mvista.com, hzhang@ch.mvista.com, yyang@ch.mvista.com,
"Witold. Jaworski@Unibw-Muenchen. De"
<witold.jaworski@unibw-muenchen.de>,
arnd.heursch@unibw-muenchen.de
Subject: Re: [ANNOUNCE] Linux 2.6 Real Time Kernel
Date: Fri, 15 Oct 2004 09:40:39 -0700 [thread overview]
Message-ID: <20041015164039.GA1265@us.ibm.com> (raw)
In-Reply-To: <20041015154542.GA8257@elte.hu>
On Fri, Oct 15, 2004 at 05:45:42PM +0200, Ingo Molnar wrote:
>
> * Paul E. McKenney <paulmck@us.ibm.com> wrote:
>
> > One caution (which you are no doubt already aware of) -- if an RCU
> > algorithm that reads (rcu_read_lock()/rcu_read_unlock()) in process
> > context and updates in softirq/bh/irq context, you can see deadlocks.
>
> yeah - but in the PREEMPT_REALTIME kernel there are simply no irq or
> softirq contexts in process contexts - everything is a task. So
> everything can (and does) block.
OK, am probably confused, but I thought that the whole point of your
PREEMPT_REALTIME implementation of rcu_read_lock_rt() was to enable
preemption in the RCU read-side critical section. If this is indeed
the case, then it looks to me like code that would run in softirq/bh/irq
context in a kernel compiled non-PREEMPT_REALTIME could now run during
the time that a code path running under rcu_read_lock_rt() was preempted.
If so, then the kernel can end up freeing a data item that the preempted
RCU read-side critical section is still referencing.
OK, so what am I missing here?
Thanx, Paul
next prev parent reply other threads:[~2004-10-15 16:46 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-09 5:59 [ANNOUNCE] Linux 2.6 Real Time Kernel Sven-Thorsten Dietrich
2004-10-09 6:40 ` Lee Revell
2004-10-09 7:33 ` Daniel Walker
2004-10-09 7:42 ` Lee Revell
2004-10-09 23:40 ` Matthias Urlichs
2004-10-09 8:52 ` Lee Revell
2004-10-09 23:20 ` Dave Hansen
2004-10-09 23:24 ` Lee Revell
2004-10-09 10:51 ` Måns Rullgård
2004-10-09 13:15 ` Måns Rullgård
2004-10-09 21:20 ` Lee Revell
2004-10-09 21:35 ` Måns Rullgård
2004-10-09 21:37 ` Lee Revell
2004-10-09 21:45 ` Måns Rullgård
2004-10-09 21:55 ` Lee Revell
2004-10-09 22:21 ` Måns Rullgård
2004-10-09 23:52 ` Lee Revell
2004-10-10 0:05 ` Måns Rullgård
2004-10-10 0:45 ` Lee Revell
2004-10-10 1:05 ` Måns Rullgård
2004-10-10 1:09 ` Lee Revell
2004-10-10 0:43 ` Micha Feigin
2004-10-10 1:08 ` Måns Rullgård
2004-10-09 17:41 ` Karim Yaghmour
2004-10-09 18:30 ` Lee Revell
2004-10-09 21:26 ` stefan.eletzhofer
2004-10-09 19:30 ` Lee Revell
2004-10-09 19:38 ` Måns Rullgård
2004-10-09 21:38 ` stefan.eletzhofer
2004-10-09 19:47 ` Lee Revell
2004-10-09 20:11 ` Karim Yaghmour
2004-10-09 20:14 ` Lee Revell
2004-10-09 20:53 ` Karim Yaghmour
2004-10-09 20:59 ` Lee Revell
2004-10-09 20:20 ` Robert Love
2004-10-09 20:25 ` Lee Revell
2004-10-10 1:15 ` Lee Revell
2004-10-10 8:46 ` Ingo Molnar
2004-10-10 19:41 ` Daniel Walker
2004-10-10 19:46 ` Ingo Molnar
2004-10-10 21:20 ` Andrew Morton
2004-10-10 21:59 ` Ingo Molnar
2004-10-11 17:53 ` Daniel Walker
2004-10-11 20:49 ` Ingo Molnar
2004-10-11 21:44 ` Sven Dietrich
2004-10-11 21:54 ` Ingo Molnar
2004-10-11 23:05 ` Sven Dietrich
2004-10-12 5:50 ` Ingo Molnar
2004-10-14 5:09 ` Dipankar Sarma
2004-10-14 7:18 ` Ingo Molnar
2004-10-15 14:59 ` Paul E. McKenney
2004-10-15 15:45 ` Ingo Molnar
2004-10-15 16:40 ` Paul E. McKenney [this message]
2004-10-15 16:45 ` Paul E. McKenney
2004-10-17 17:12 ` Ingo Molnar
2004-10-12 18:50 ` Daniel Walker
2004-10-12 19:46 ` [Ext-rt-dev] " Thomas Gleixner
2004-10-12 20:31 ` Sven Dietrich
2004-10-12 20:37 ` Thomas Gleixner
2004-10-13 0:30 ` George Anzinger
2004-10-12 21:12 ` Bill Huey
2004-10-12 21:24 ` Bill Huey
2004-10-12 21:32 ` Thomas Gleixner
2004-10-12 23:13 ` Bill Huey
2004-10-12 21:41 ` Sven Dietrich
2004-10-12 22:57 ` Bill Huey
2004-10-12 23:17 ` Adam Heath
2004-10-12 23:36 ` Lee Revell
2004-10-12 23:25 ` Thomas Gleixner
2004-10-13 2:02 ` K.R. Foley
2004-10-13 13:39 ` Martijn Sipkema
2004-10-13 13:26 ` La Monte H.P. Yarroll
2004-10-13 15:04 ` Martijn Sipkema
2004-10-13 14:55 ` Kurt Wall
2004-10-13 14:52 ` Christoph Hellwig
2004-10-13 15:56 ` Lee Revell
2004-10-13 16:13 ` Robert Love
2004-10-13 17:14 ` Martijn Sipkema
2004-10-13 3:55 ` Bill Huey
2004-10-12 22:00 ` Thomas Gleixner
2004-10-12 22:36 ` Bill Huey
2004-10-12 23:10 ` Thomas Gleixner
2004-10-12 23:33 ` Bill Huey
2004-10-12 23:37 ` Thomas Gleixner
2004-10-12 23:52 ` Bill Huey
2004-10-13 0:59 ` Valdis.Kletnieks
2004-10-10 12:21 ` John Richard Moser
2004-10-10 17:26 ` Lee Revell
2004-10-10 18:45 ` John Richard Moser
2004-10-10 20:20 ` Ingo Molnar
2004-10-10 20:44 ` John Richard Moser
2004-10-10 17:29 ` Daniel Walker
-- strict thread matches above, loose matches on Subject: below --
2004-10-09 11:38 John Hedditch
2004-10-09 22:54 Sven Dietrich
2004-10-11 15:28 Vadim Lebedev
2004-10-11 15:50 ` Eugeny S. Mints
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=20041015164039.GA1265@us.ibm.com \
--to=paulmck@us.ibm.com \
--cc=abatyrshin@ru.mvista.com \
--cc=akpm@osdl.org \
--cc=amakarov@ru.mvista.com \
--cc=arnd.heursch@unibw-muenchen.de \
--cc=dipankar@in.ibm.com \
--cc=dwalker@mvista.com \
--cc=emints@ru.mvista.com \
--cc=ext-rt-dev@mvista.com \
--cc=hzhang@ch.mvista.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=sdietrich@mvista.com \
--cc=witold.jaworski@unibw-muenchen.de \
--cc=yyang@ch.mvista.com \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.