From: Helge Hafting <helgehaf@aitel.hist.no>
To: Rusty Russell <rusty@rustcorp.com.au>, linux-kernel@vger.kernel.org
Subject: Re: [RFC] Raceless module interface
Date: Fri, 13 Sep 2002 10:18:51 +0200 [thread overview]
Message-ID: <3D819F6B.FBECDF0F@aitel.hist.no> (raw)
In-Reply-To: 20020912031345.760A32C061@lists.samba.org
Rusty Russell wrote:
>
> In message <20020912030933.A13608@kushida.apsleyroad.org> you write:
> > I don't see the point in this at all.
>
> Yes, I'm starting to realize that.
>
> Frankly, I'm sick of pointing out the same problems individually to
> every shallow thinker who thinks that "it's easy".
>
> The fundamental problems with modules are as follows:
> A) Many places in the kernel do not increment module reference counts
> for you, and it is difficult currently write a module which safely
> looks after its own reference counts (see
> net/ipv4/netfilter/ip_conntrack_core.c's ip_conntrack_cleanup())
This sort of thing makes correct unloading hard, but in my eyes it
is an argument for changing the module interface to something better
and say "that thing CAN'T be a module of its own!"
What if we *require* modules to use some open/close reference count that
don't change so often as to be a performance problem?
It makes the unloading/reloading problem easier, similiar to
mount/umount.
It'll work for lots of modules, such as:
* drivers for hardware devices, char, block, and NIC.
* filesystems
Things with no easy refcounting (and it cannot even be grafted on)
will have to be non-modular, or folded into some parent module.
Maybe IP connection tracking can't be modular with these rules - so
what? Make it compiled-in, or a part of the IPV4-module. So
if you really need to load and unload that you unload the
ipv4_with_conntrack module and then load a ipv4_without_conntrack
module.
To me, it seems like the current module interface is too fine-grained,
and that cause trouble. I.e. the overhead of correct refcounting
is so high in some cases that it isn't used - causing trouble
with safe unloading. The solution is to say no to such modules.
Making them work isn't easy - but why try?
Helge Hafting
next prev parent reply other threads:[~2002-09-13 8:14 UTC|newest]
Thread overview: 90+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-04 18:02 Question about pseudo filesystems Jamie Lokier
2002-09-07 12:00 ` Daniel Phillips
2002-09-07 13:36 ` Alexander Viro
2002-09-07 18:27 ` Jamie Lokier
2002-09-07 19:47 ` Alexander Viro
2002-09-08 2:21 ` Jamie Lokier
2002-09-08 2:43 ` Alexander Viro
2002-09-15 1:41 ` Moving a mount point (was Re: Question about pseudo filesystems) Rob Landley
2002-09-08 16:00 ` Question about pseudo filesystems Daniel Phillips
2002-09-09 19:48 ` Jamie Lokier
2002-09-09 20:06 ` Daniel Phillips
2002-09-10 0:44 ` Jamie Lokier
2002-09-10 1:40 ` Daniel Phillips
2002-09-10 1:56 ` Jamie Lokier
2002-09-10 2:53 ` Daniel Phillips
2002-09-10 3:26 ` Jamie Lokier
2002-09-10 3:47 ` Daniel Phillips
2002-09-10 9:15 ` Daniel Phillips
2002-09-10 10:17 ` Roman Zippel
2002-09-11 18:35 ` [RFC] Raceless module interface Daniel Phillips
2002-09-11 18:53 ` Oliver Neukum
2002-09-11 19:20 ` Daniel Phillips
2002-09-11 20:29 ` Oliver Neukum
2002-09-11 21:15 ` Daniel Phillips
2002-09-11 21:26 ` Jamie Lokier
2002-09-11 21:47 ` Daniel Phillips
2002-09-12 1:42 ` Rusty Russell
2002-09-12 2:09 ` Jamie Lokier
2002-09-12 3:13 ` Rusty Russell
2002-09-12 3:47 ` Daniel Phillips
2002-09-12 3:53 ` Alexander Viro
2002-09-12 4:11 ` Daniel Phillips
2002-09-12 4:40 ` Rusty Russell
2002-09-12 5:27 ` Daniel Phillips
2002-09-12 14:46 ` Gerhard Mack
2002-09-13 0:39 ` Rusty Russell
2002-09-13 2:23 ` Daniel Phillips
2002-09-12 5:35 ` Rusty Russell
2002-09-12 4:52 ` Rusty Russell
2002-09-12 5:58 ` Daniel Phillips
2002-09-12 7:00 ` Rusty Russell
2002-09-13 8:18 ` Helge Hafting [this message]
2002-09-12 3:32 ` Daniel Phillips
2002-09-12 1:31 ` Rusty Russell
2002-09-12 9:10 ` Oliver Neukum
2002-09-12 11:27 ` Roman Zippel
2002-09-12 13:03 ` Rusty Russell
2002-09-12 13:44 ` Roman Zippel
2002-09-13 1:30 ` Rusty Russell
2002-09-13 2:19 ` Daniel Phillips
2002-09-13 6:51 ` Rusty Russell
2002-09-13 13:34 ` Daniel Phillips
2002-09-13 13:52 ` Thunder from the hill
2002-09-13 14:09 ` Daniel Phillips
2002-09-13 14:33 ` Thunder from the hill
2002-09-13 14:44 ` Daniel Phillips
2002-09-13 14:59 ` Thunder from the hill
2002-09-13 15:17 ` Daniel Phillips
2002-09-13 15:27 ` Thunder from the hill
2002-09-13 15:37 ` Daniel Phillips
2002-09-16 2:17 ` Rusty Russell
2002-09-16 16:13 ` Daniel Phillips
2002-09-16 16:36 ` Understanding the Principles of Argumentation #3 Daniel Phillips
2002-09-16 16:42 ` Robinson Maureira Castillo
2002-09-16 17:29 ` Cort Dougan
2002-09-16 22:31 ` David Woodhouse
2002-10-01 14:13 ` Daniel Phillips
2002-10-01 14:27 ` David Woodhouse
2002-09-13 15:59 ` [RFC] Raceless module interface Daniel Phillips
2002-09-13 3:14 ` David Gibson
2002-09-13 10:35 ` Roman Zippel
2002-09-13 13:53 ` Daniel Phillips
2002-09-13 15:13 ` Roman Zippel
2002-09-13 15:30 ` Daniel Phillips
2002-09-13 15:55 ` Roman Zippel
2002-09-13 16:09 ` Daniel Phillips
2002-09-13 16:39 ` Thunder from the hill
2002-09-13 17:12 ` Daniel Phillips
2002-09-16 0:24 ` Bill Davidsen
2002-09-16 1:49 ` Rusty Russell
2002-09-16 21:36 ` Roman Zippel
2002-09-16 21:48 ` Daniel Phillips
2002-09-16 22:44 ` Roman Zippel
2002-09-11 15:28 ` Question about pseudo filesystems Bill Davidsen
2002-09-11 19:36 ` Daniel Phillips
2002-09-09 20:12 ` Daniel Phillips
2002-09-09 22:56 ` Jamie Lokier
2002-09-10 1:39 ` Alexander Viro
2002-09-09 20:18 ` Daniel Phillips
2002-09-10 6:48 ` Kai Henningsen
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