lkml.org 
[lkml]   [2002]   [Sep]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [RFC] Raceless module interface
Date
On Friday 13 September 2002 03:30, Rusty Russell wrote:
> In message <Pine.LNX.4.44.0209121520300.28515-100000@serv> you write:
> > The usecount is optional, the only important question a module must be
> > able to answer is: Are there any objects/references belonging to the
> > module? It's a simple yes/no question. If a module can't answer that, it
> > likely has more problem than just module unloading.
>
> Ah, we're assuming you insert synchronize_kernel() between the call
> to stop and the call to exit?
>
> In which case *why* do you check the use count *inside* exit_affs_fs?
> Why not get exit_module() to do "if (mod->usecount() != 0) return
> -EBUSY; else mod->exit();"?

Because mod->usecount may be a totally inadequate way of determining
if a module is busy. How does it work for LSM, for example?

> There's the other issue of symmetry. If you allocate memory, in
> start, do you clean it up in stop or exit?

Actually, I'm going to press you on why you think you even need a
two stage stop. I know you have your reasons, but I doubt any of
the effects you aim at cannot be achieved with a single stage
stop/exit. Could you please summarize the argument in favor of the
two stage stop?

> Similarly for other
> resources: you call mod->exit() every time start fails, so that is
> supposed to check that mod->start() succeeded?

He does? That's not right. ->start should clean up after itself if
it fails, like any other good Linux citizen.

> Of course, separating start into "init" and "start" allows you to
> solve the half-initialized problem as well as clarify the rules.

I doubt it gives any new capability at all. The same with the
entrenched separation at the user level between create and init
module: what does it give you that an error exit from a single
create/init would not? Sure, I know it's not going to change,
but I'd like to know what the thinking was, and especially, if
there's a non-bogus reason, I'd like to know it.

--
Daniel
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:28    [W:0.177 / U:0.328 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site