lkml.org 
[lkml]   [2003]   [Feb]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC] Is an alternative module interface needed/possible?
Roman Zippel wrote:
> If it was perfectly good, we hadn't a problem. :)

I said we he have the method. Now we need to use it properly :-)

> You're skipping ahead. You haven't solved the problem yet, but you're
> already jumping to conclusions. :-)

The solution is another issue. I simply stated that the problem
happens with or without modules.

> module count: by design this only works for entries, which are removed
> during module exit, but not for dynamic entries.

Works only for modules, not good.

> failure: if the object is still busy, we just return -EBUSY. This is
> simple, but this doesn't work for modules, since during module exit you
> can't fail anymore.

That's a modules API problem. And yes, I think modules should
eventually be able to say that they're busy.

> callbacks: the callback function itself had to be protected somehow, so
> just to unregister a proc entry, you have to register a callback. To
> unregister that callback, it would be silly to use another callback and

If all you want to do is to decrement the module count, you could
have a global handler for this that is guaranteed not to reside
in a module.

By the way, a loong time ago, in the modules thread, I suggested
a "decrement_module_count_and_return" function [1]. Such a
construct would be useful in this specific case.

[1] http://www.uwsg.iu.edu/hypermail/linux/kernel/0207.0/0147.html

> failure doesn't work with modules, so that only leaves the module count.

And how would you ensure correct access to static data in the
absence of modules ? Any solution that _requires_ a module count
looks highly suspicious to me.

Likewise, possibly dynamically allocated data that is synchronized
by the caller, e.g. "user" in "struct proc_dir_entry".

> The last solution sounds complicated, but exactly this is done for
> filesystems and we didn't really get rid of the second reference count, we
> just moved it somewhere else, where it hurts least.

Hmm, I'm confused. With "filesystem", do you mean the file system
driver per se (e.g. "ext3"), or a specific instance of such a file
system (e.g. /dev/hda1 mounted on /) ?

- Werner

--
_________________________________________________________________________
/ Werner Almesberger, Buenos Aires, Argentina wa@almesberger.net /
/_http://www.almesberger.net/____________________________________________/
-
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 13:33    [W:0.121 / U:4.908 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site