Re: Please do not yell at people for trying to help you.

[Matt Thomas <matt%3am-software.com@localhost>]

On Nov 12, 2010, at 8:02 PM, Johnny Billquist wrote:

> On 2010-11-13 04:49, Matt Thomas wrote:
>> 
>> simple locks are not mutexes.  mutexes are more complex and
>> test-and-set isn't adequate to do the job.
> 
> I (obviously) totally disagree... :-)
> A mutex is simply just an object that only one entity can own at a time. 
> Hence "mutex", or mutually exclusive. A test-and-set is precisely all that is 
> needed to implement this.
> And if you implement a mutex with spin locking, then you also need to make 
> sure that you do not get deadlocks. Either by detecting such things, or make 
> sure they don't happen. But that is outside the subject of the test-and-set 
> part.

Execpt most of our mutexes are sleep mutexes.  Only a small minority
are spin mutexes and those are already implemented using BBSSI/BBCCI.