Messages in this thread | | | From | Daniel Phillips <> | Subject | Re: [PATCH] In-kernel module loader 1/7 | Date | Tue, 15 Oct 2002 17:28:33 +0200 |
| |
On Tuesday 15 October 2002 05:25, Rusty Russell wrote: > In message <E17w2XF-0005oW-00@starship> you write: > > Not being able to unload LSM would suck enormously. At last count, we > > knew how to do this: > > > > 1) Unhook the function hooks (using a call table simplifies this) > > 2) Schedule on each CPU to ensure all tasks are out of the module > > 3) A schedule where the module count is incremented doesn't count > > > > and we rely on the rule that and module code that could sleep must be > > bracketed by inc/dec of the module count. > > > > Did somebody come up with a reason why this will not work? > > It won't quite work if the hooks can sleep. You can say "don't sleep" > or have a wedge which does the "try_inc_mod_count()" then calls into > the module (and returns some default if it can't inc the module count).
Right. By coincidence, I found myself thinking about this very problem as I re-materialized this morning. If TRY_INC_MOD_COUNT also ors a flag (which it does now, for other reasons) then:
1) Clear the mod_inc flag 2) Unhook the function hooks 3) Schedule on each CPU 4) If the mod_inc flag is set, repeat from (1)
This should perform acceptably well, and would only be done in cases where the existing TRY_INC_MOD_COUNT strategy can't be used.
> You can't disable preemption before calling in, because there is no > way to sleep with preemption disabled. 8(
Why is that harder than bumping a counter that makes preempt_schedule return without doing anything?
-- 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/
| |