Re: CVS commit: src/sys/compat/sa

[Christoph Egger <Christoph_Egger%gmx.de@localhost>]

Bill Stouder-Studenmund wrote:
> On Mon, Oct 27, 2008 at 08:24:06PM +0100, Christoph Egger wrote:
>> Bill Stouder-Studenmund wrote:
>>> If I'm wrong, I think the thing to do is disable kernel preemption in 
>>> sa_upcall().
>> With kernel preemption enabled, curlwp may unlock a different lwp than
>> the one you locked.
>>
>> If you are sure, curlwp never changes between lock and unlock, then
>> my complaint is pointless. But if it can, then you have to either cache
>> curlwp in a variable or disable kernel preemption for this code section.
> 
> How could curlwp unlock a different lwp?
> 
> I agree that with preemption, curlwp could change during the call. Another 
> thread could get run. However for our unlock to run, we have to have been 
> switched _back_ to our context, so curlwp is back to whatever it was when 
> our routine started.

Sounds like you are sure, the curlwp is safe to use.
In that case, my concern is pointless.

Christoph