Re: simple handling of module removals Re: [OKS] Module removal

In article <[e-mail]>,
you write:
>
>Is it just the mod_dec_use_count; return/unload race we're worried about? 
>>I'm not clear on why this is hard.  I'd think it would be sufficient just
>to 
>walk all runnable processes to ensure none has an execution address inside
>the
>module.  For smp, an ipi would pick up the current process on each cpu.
>
>At this point the use count must be zero and the module deregistered, so
>all 
>we're interested in is that every process that dec'ed the module's use
>count 
>has succeeded in executing its way out of the module.  If not, we try
>again 
>later, or if we're impatient, also bump any processes still inside the
>module 
>to the front of the run queue.
>
>I'm sure I must have missed something.
>

Identifying the valid execution address in a stack traceback isn't
possible on many architectures (in particular, i386 without debugging
support enabled) so this wouldn't work if one of the functions had
called into a function outside the module.

On the other hand, if it was made a rule that any code in a module that
might theoretically be running without reference counts wasn't allowed
to call out of the module (or maybe was allowed to call out to a very
specific small set of library functions that were known to the module
system), then something like this might work.

Paul