From: Christoph Hellwig <hch@caldera.de>
To: kaos@ocs.com.au (Keith Owens)
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
linux-kernel@vger.kernel.org,
Philipp Rumpf <prumpf@mandrakesoft.com>
Subject: Re: Linux 2.4.1-ac15
Date: Mon, 19 Feb 2001 14:25:39 +0100 [thread overview]
Message-ID: <200102191325.OAA12026@ns.caldera.de> (raw)
In-Reply-To: <30512.982588558@ocs3.ocs-net>
In article <30512.982588558@ocs3.ocs-net> you wrote:
> No need for a callin routine, you can get this for free as part of
> normal scheduling. The sequence goes :-
>
> if (use_count == 0) {
> module_unregister();
> wait_for_at_least_one_schedule_on_every_cpu();
> if (use_count != 0) {
> module_register(); /* lost the unregister race */
> }
> else {
> /* nobody can enter the module now */
> module_release_resources();
> unlink_module_from_list();
> wait_for_at_least_one_schedule_on_every_cpu();
> free_module_storage();
> }
> }
>
> wait_for_at_least_one_schedule_on_every_cpu() prevents the next
> operation until at least one schedule has been executed on every cpu.
> Whether this is done as a call back or a separate kernel thread that
> schedules itself on every cpu or the current process scheduling itself
> on every cpu is an implementation detail. All that matters is that any
> other cpu that might have been accessing the module has gone through
> schedule and therefore is no longer accessing the module's data or
> code.
You just reinvented the read-copy-update model
(http://www.rdrop.com/users/paulmck/rclock/intro/rclock_intro.html)...
The mail proposing that locking model for module unloading is not yet
in the arvhices, sorry.
Christoph
P.S. Weren't you Cc:'ed on that mail?
--
Of course it doesn't work. We've performed a software upgrade.
next prev parent reply other threads:[~2001-02-19 13:26 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-02-15 23:15 Linux 2.4.1-ac15 Alan Cox
2001-02-19 9:47 ` Philipp Rumpf
2001-02-19 11:35 ` Alan Cox
2001-02-19 11:54 ` Philipp Rumpf
2001-02-19 16:03 ` Alan Cox
2001-02-19 16:21 ` Philipp Rumpf
2001-02-19 16:27 ` Alan Cox
2001-02-19 16:34 ` Philipp Rumpf
2001-02-19 16:41 ` Alan Cox
2001-02-19 16:48 ` Philipp Rumpf
2001-02-19 17:03 ` Alan Cox
2001-02-21 3:02 ` Rusty Russell
2001-02-21 12:01 ` Alan Cox
2001-02-22 2:05 ` Rusty Russell
2001-02-22 10:22 ` Alan Cox
2001-02-23 0:01 ` Philipp Rumpf
2001-02-22 2:27 ` Linus Torvalds
2001-02-22 10:29 ` Alan Cox
2001-02-23 20:40 ` Andrea Arcangeli
2001-02-23 21:09 ` Linus Torvalds
2001-02-24 4:04 ` Andrea Arcangeli
2001-02-24 4:54 ` Andrea Arcangeli
2001-02-19 11:54 ` Keith Owens
2001-02-19 12:15 ` Philipp Rumpf
2001-02-19 13:15 ` Keith Owens
2001-02-19 13:25 ` Christoph Hellwig [this message]
2001-02-19 21:32 ` Keith Owens
2001-02-19 13:36 ` Philipp Rumpf
2001-02-19 15:23 ` Manfred Spraul
2001-02-19 16:04 ` Alan Cox
2001-02-19 21:52 ` Keith Owens
2001-02-20 12:29 ` Philipp Rumpf
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