summaryrefslogtreecommitdiffstats
path: root/sys/kern/subr_rlist.c
blob: 3a61debcadac8311cc345a8ad6457b86d00d3e72 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
/*
 * Copyright (c) 1992 William F. Jolitz, TeleMuse
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This software is a component of "386BSD" developed by
	William F. Jolitz, TeleMuse.
 * 4. Neither the name of the developer nor the name "386BSD"
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS A COMPONENT OF 386BSD DEVELOPED BY WILLIAM F. JOLITZ
 * AND IS INTENDED FOR RESEARCH AND EDUCATIONAL PURPOSES ONLY. THIS
 * SOFTWARE SHOULD NOT BE CONSIDERED TO BE A COMMERCIAL PRODUCT.
 * THE DEVELOPER URGES THAT USERS WHO REQUIRE A COMMERCIAL PRODUCT
 * NOT MAKE USE THIS WORK.
 *
 * FOR USERS WHO WISH TO UNDERSTAND THE 386BSD SYSTEM DEVELOPED
 * BY WILLIAM F. JOLITZ, WE RECOMMEND THE USER STUDY WRITTEN
 * REFERENCES SUCH AS THE  "PORTING UNIX TO THE 386" SERIES
 * (BEGINNING JANUARY 1991 "DR. DOBBS JOURNAL", USA AND BEGINNING
 * JUNE 1991 "UNIX MAGAZIN", GERMANY) BY WILLIAM F. JOLITZ AND
 * LYNNE GREER JOLITZ, AS WELL AS OTHER BOOKS ON UNIX AND THE
 * ON-LINE 386BSD USER MANUAL BEFORE USE. A BOOK DISCUSSING THE INTERNALS
 * OF 386BSD ENTITLED "386BSD FROM THE INSIDE OUT" WILL BE AVAILABLE LATE 1992.
 *
 * THIS SOFTWARE IS PROVIDED BY THE DEVELOPER ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE DEVELOPER BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */
/*
 * Changes Copyright (C) 1995, David Greenman & John Dyson; This software may
 * be used, modified, copied, distributed, and sold, in both source and
 * binary form provided that the above copyright and these terms are
 * retained. Under no circumstances is the author responsible for the proper
 * functioning of this software, nor does the author assume any responsibility
 * for damages incurred with its use.
 *
 *	$Id: subr_rlist.c,v 1.22 1997/09/02 20:05:51 bde Exp $
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/rlist.h>
#include <vm/vm.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>

/*
 * Resource lists.
 */

#define RLIST_MIN 128
static int rlist_count=0;
static struct rlist *rlfree;

static struct rlist	*rlist_malloc __P((void));
static inline void	rlist_mfree __P((struct rlist *rl));

static struct rlist *
rlist_malloc()
{
	struct rlist *rl;
	int i;
	while( rlist_count < RLIST_MIN) {
		int s = splhigh();
		rl = (struct rlist *)kmem_alloc(kernel_map, PAGE_SIZE);
		splx(s);
		if( !rl)
			break;

		for(i=0;i<(PAGE_SIZE/(sizeof *rl));i++) {
			rl->rl_next = rlfree;
			rlfree = rl;
			rlist_count++;
			rl++;
		}
	}

	if( (rl = rlfree) == 0 )
		panic("Cannot get an rlist entry");

	--rlist_count;
	rlfree = rl->rl_next;
	return rl;
}

static inline void
rlist_mfree(rl)
	struct rlist *rl;
{
	rl->rl_next = rlfree;
	rlfree = rl;
	++rlist_count;
}

void
rlist_free(rlh, start, end)
	struct rlisthdr *rlh;
	u_int start, end;
{
	struct rlist **rlp = &rlh->rlh_list;
	struct rlist *prev_rlp = NULL, *cur_rlp = *rlp, *next_rlp = NULL;
	int s;

	s = splhigh();
	while (rlh->rlh_lock & RLH_LOCKED) {
		rlh->rlh_lock |= RLH_DESIRED;
		tsleep(rlh, PSWP, "rlistf", 0);
	}
	rlh->rlh_lock |= RLH_LOCKED;
	splx(s);

	/*
	 * Traverse the list looking for an entry after the one we want
	 * to insert.
	 */
	while (cur_rlp != NULL) {
		if (start < cur_rlp->rl_start)
			break;
#ifdef DIAGNOSTIC
		if (prev_rlp) {
			if (prev_rlp->rl_end + 1 == cur_rlp->rl_start)
				panic("rlist_free: missed coalesce opportunity");
			if (prev_rlp->rl_end ==  cur_rlp->rl_start)
				panic("rlist_free: entries overlap");
			if (prev_rlp->rl_end > cur_rlp->rl_start)
				panic("entries out of order");
		}
#endif
		prev_rlp = cur_rlp;
		cur_rlp = cur_rlp->rl_next;
	}

	if (cur_rlp != NULL) {

		if (end >= cur_rlp->rl_start)
			panic("rlist_free: free end overlaps already freed area");

		if (prev_rlp) {
			if (start <= prev_rlp->rl_end)
				panic("rlist_free: free start overlaps already freed area");
			/*
			 * Attempt to append
			 */
			if (prev_rlp->rl_end + 1 == start) {
				prev_rlp->rl_end = end;
				/*
				 * Attempt to prepend and coalesce
				 */
				if (end + 1 == cur_rlp->rl_start) {
					prev_rlp->rl_end = cur_rlp->rl_end;
					prev_rlp->rl_next = cur_rlp->rl_next;
					rlist_mfree(cur_rlp);
				}
				goto done;
			}
		}
		/*
		 * Attempt to prepend
		 */
		if (end + 1 == cur_rlp->rl_start) {
			cur_rlp->rl_start = start;
			goto done;
		}
	}
	/*
	 * Reached the end of the list without finding a larger entry.
	 * Append to last entry if there is one and it's adjacent.
	 */
	if (prev_rlp) {
		if (start <= prev_rlp->rl_end)
			panic("rlist_free: free start overlaps already freed area at list tail");
		/*
		 * Attempt to append
		 */
		if (prev_rlp->rl_end + 1 == start) {
			prev_rlp->rl_end = end;
			goto done;
		}
	}

	/*
	 * Could neither append nor prepend; allocate a new entry.
	 */
	next_rlp = cur_rlp;
	cur_rlp = rlist_malloc();
	cur_rlp->rl_start = start;
	cur_rlp->rl_end = end;
	cur_rlp->rl_next = next_rlp;
	if (prev_rlp) {
		prev_rlp->rl_next = cur_rlp;
	} else {
		/*
		 * No previous - this entry is the new list head.
		 */
		*rlp = cur_rlp;
	}

done:
	rlh->rlh_lock &= ~RLH_LOCKED;
	if (rlh->rlh_lock & RLH_DESIRED) {
		wakeup(rlh);
		rlh->rlh_lock &= ~RLH_DESIRED;
	}
	return;
}

/*
 * Obtain a region of desired size from a resource list.
 * If nothing available of that size, return 0. Otherwise,
 * return a value of 1 and set resource start location with
 * "*loc". (Note: loc can be zero if we don't wish the value)
 */
int
rlist_alloc (rlh, size, loc)
	struct rlisthdr *rlh;
	unsigned size, *loc;
{
	struct rlist **rlp = &rlh->rlh_list;
	register struct rlist *lp;
	int s;
	register struct rlist *olp = 0;

	s = splhigh();
	while (rlh->rlh_lock & RLH_LOCKED) {
		rlh->rlh_lock |= RLH_DESIRED;
		tsleep(rlh, PSWP, "rlistf", 0);
	}
	rlh->rlh_lock |= RLH_LOCKED;
	splx(s);

	/* walk list, allocating first thing that's big enough (first fit) */
	for (; *rlp; rlp = &((*rlp)->rl_next))
		if(size <= (*rlp)->rl_end - (*rlp)->rl_start + 1) {

			/* hand it to the caller */
			if (loc) *loc = (*rlp)->rl_start;
			(*rlp)->rl_start += size;

			/* did we eat this element entirely? */
			if ((*rlp)->rl_start > (*rlp)->rl_end) {
				lp = (*rlp)->rl_next;
				rlist_mfree(*rlp);
				/*
				 * if the deleted element was in fromt
				 * of the list, adjust *rlp, else don't.
				 */
				if (olp) {
					olp->rl_next = lp;
				} else {
					*rlp = lp;
				}
			}

			rlh->rlh_lock &= ~RLH_LOCKED;
			if (rlh->rlh_lock & RLH_DESIRED) {
				wakeup(rlh);
				rlh->rlh_lock &= ~RLH_DESIRED;
			}
			return (1);
		} else {
			olp = *rlp;
		}

	rlh->rlh_lock &= ~RLH_LOCKED;
	if (rlh->rlh_lock & RLH_DESIRED) {
		wakeup(rlh);
		rlh->rlh_lock &= ~RLH_DESIRED;
	}
	/* nothing in list that's big enough */
	return (0);
}

/*
 * Finished with this resource list, reclaim all space and
 * mark it as being empty.
 */
void
rlist_destroy (rlh)
	struct rlisthdr *rlh;
{
	struct rlist **rlp = &rlh->rlh_list;
	struct rlist *lp, *nlp;

	lp = *rlp;
	*rlp = 0;
	for (; lp; lp = nlp) {
		nlp = lp->rl_next;
		rlist_mfree(lp);
	}
}
OpenPOWER on IntegriCloud