Subversion Repositories planix.SVN

Rev

Rev 2 | Details | Compare with Previous | Last modification | View Log | RSS feed

Rev Author Line No. Line
2 - 1 
#include "u.h"
2 
#include "lib.h"
3 
#include "dat.h"
4 
#include "fns.h"
5 
 
6 
static void
7 
queue(Proc **first, Proc **last)
8 
{
9 
	Proc *t;
10 
 
11 
	t = *last;
12 
	if(t == 0)
13 
		*first = up;
14 
	else
15 
		t->qnext = up;
16 
	*last = up;
17 
	up->qnext = 0;
18 
}
19 
 
20 
static Proc*
21 
dequeue(Proc **first, Proc **last)
22 
{
23 
	Proc *t;
24 
 
25 
	t = *first;
26 
	if(t == 0)
27 
		return 0;
28 
	*first = t->qnext;
29 
	if(*first == 0)
30 
		*last = 0;
31 
	return t;
32 
}
33 
 
34 
void
35 
qlock(QLock *q)
36 
{
37 
	lock(&q->lk);
38 
 
39 
	if(q->hold == 0) {
40 
		q->hold = up;
41 
		unlock(&q->lk);
42 
		return;
43 
	}
44 
 
45 
	/*
46 
	 * Can't assert this because of RWLock
47 
	assert(q->hold != up);
48 
	 */
49 
 
50 
	queue((Proc**)&q->first, (Proc**)&q->last);
51 
	unlock(&q->lk);
52 
	procsleep();
53 
}
54 
 
55 
int
56 
canqlock(QLock *q)
57 
{
58 
	lock(&q->lk);
59 
	if(q->hold == 0) {
60 
		q->hold = up;
61 
		unlock(&q->lk);
62 
		return 1;
63 
	}
64 
	unlock(&q->lk);
65 
	return 0;
66 
}
67 
 
68 
void
69 
qunlock(QLock *q)
70 
{
71 
	Proc *p;
72 
 
73 
	lock(&q->lk);
74 
	/*
75 
	 * Can't assert this because of RWlock
76 
	assert(q->hold == CT);
77 
	 */
78 
	p = dequeue((Proc**)&q->first, (Proc**)&q->last);
79 
	if(p) {
80 
		q->hold = p;
81 
		unlock(&q->lk);
82 
		procwakeup(p);
83 
	} else {
84 
		q->hold = 0;
85 
		unlock(&q->lk);
86 
	}
87 
}
88 
 
89 
int
90 
holdqlock(QLock *q)
91 
{
92 
	return q->hold == up;
93 
}
94