From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <b1b442067ff610597d59cd246744559b@davidashen.net>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] qunlock
Date: Thu, 24 Jun 2004 02:00:43 +0500
From: dvd@davidashen.net
In-Reply-To: <7359f0490406231324515faa83@mail.gmail.com>
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> you can't do that. what if you do the first unlock,
> then someone else locks it in the interim. you'll
> unlock his lock. bad bad bad.
> 
> -rob

It happens in a critical section guarded by another mutex. 
Noone else can unlock my lock.

Should I uncomment the commented-out calls below?


void
A()
{
againA:
	qlock(a);
	qlock(q);
		if(x) {
   			qunlock(q);
			goto againA;
		}
	/* canqlock(b); */
	qunlock(b);
	qunlock(q);
	qunlock(a);
}

void
B()
{
againB:
	qlock(b);
	qlock(q);
		if(y){
			qunlock(q);
			goto againB;
		}
	/* canqlock(a); */
	qunlock(a);
	qunlock(q);
	qunlock(b);
}