From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <b4b080851299e6d9b095d97cb2b7f834@davidashen.net>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] qunlock
Date: Thu, 24 Jun 2004 15:58:49 +0500
From: dvd@davidashen.net
In-Reply-To: <ac681a2a7a84be85080152b19f4f1f54@plan9.escet.urjc.es>
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> Maybe it's just that it's too early and I got soo few coffee, but,
> do meant this, didn't you?

No, I didn't; I mean that under certain condition each of the processes
steps aside and opens the way for the other one until the other one executes
at least once. 

The original code does exactly that.  Your changes just spin each of the processes once the corresponding condition becomes true.

> 
>> void
>> A()
>> {
> 
> 	qlock(a);
> againA:
> 
>> 	qlock(q);
>> 		if(x) {
>>    			qunlock(q);
>> 			goto againA;
>> 		}
> ....
> 
> 
>> void
>> B()
>> {
> 
>  	qlock(b);
> againB:
> 
>> 	qlock(q);
>> 		if(y){
>> 			qunlock(q);
>> 			goto againB;
>> 		}
> ....