xref: /dragonfly/sys/bus/cam/cam_queue.c (revision d77a7c90) 
1 /*
2  * CAM request queue management functions.
3  *
4  * Copyright (c) 1997 Justin T. Gibbs.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions, and the following disclaimer,
12  *    without modification, immediately at the beginning of the file.
13  * 2. The name of the author may not be used to endorse or promote products
14  *    derived from this software without specific prior written permission.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
20  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  *
28  * $FreeBSD: src/sys/cam/cam_queue.c,v 1.5 1999/08/28 00:40:41 peter Exp $
29  * $DragonFly: src/sys/bus/cam/cam_queue.c,v 1.4 2004/03/12 03:23:13 dillon Exp $
30  */
31 #include <sys/param.h>
32 #include <sys/systm.h>
33 #include <sys/types.h>
34 #include <sys/malloc.h>
35 
36 #include "cam.h"
37 #include "cam_ccb.h"
38 #include "cam_queue.h"
39 #include "cam_debug.h"
40 
41 static __inline int
42 		queue_cmp(cam_pinfo **queue_array, int i, int j);
43 static __inline void
44 		swap(cam_pinfo **queue_array, int i, int j);
45 static void	heap_up(cam_pinfo **queue_array, int new_index);
46 static void	heap_down(cam_pinfo **queue_array, int index,
47 			  int last_index);
48 
49 struct camq *
50 camq_alloc(int size)
51 {
52 	struct camq *camq;
53 
54 	camq = malloc(sizeof(*camq), M_DEVBUF, M_INTWAIT);
55 	camq_init(camq, size);
56 	return (camq);
57 }
58 
59 int
60 camq_init(struct camq *camq, int size)
61 {
62 	bzero(camq, sizeof(*camq));
63 	camq->array_size = size;
64 	if (camq->array_size != 0) {
65 		camq->queue_array = malloc(size * sizeof(cam_pinfo *),
66 					M_DEVBUF, M_INTWAIT);
67 		/*
68 		 * Heap algorithms like everything numbered from 1, so
69 		 * offset our pointer into the heap array by one element.
70 		 *
71 		 * XXX this is a really dumb idea.
72 		 */
73 		camq->queue_array--;
74 	}
75 	return (0);
76 }
77 
78 /*
79  * Free a camq structure.  This should only be called if a controller
80  * driver failes somehow during its attach routine or is unloaded and has
81  * obtained a camq structure.  The XPT should ensure that the queue
82  * is empty before calling this routine.
83  */
84 void
85 camq_free(struct camq *queue)
86 {
87 	if (queue != NULL) {
88 		camq_fini(queue);
89 		free(queue, M_DEVBUF);
90 	}
91 }
92 
93 void
94 camq_fini(struct camq *queue)
95 {
96 	if (queue->queue_array != NULL) {
97 		/*
98 		 * Heap algorithms like everything numbered from 1, so
99 		 * our pointer into the heap array is offset by one element.
100 		 */
101 		queue->queue_array++;
102 		free(queue->queue_array, M_DEVBUF);
103 	}
104 }
105 
106 u_int32_t
107 camq_resize(struct camq *queue, int new_size)
108 {
109 	cam_pinfo **new_array;
110 
111 #ifdef DIAGNOSTIC
112 	if (new_size < queue->entries)
113 		panic("camq_resize: New queue size can't accomodate "
114 		      "queued entries.");
115 #endif
116 	new_array = malloc(new_size * sizeof(cam_pinfo *), M_DEVBUF, M_INTWAIT);
117 
118 	/*
119 	 * Heap algorithms like everything numbered from 1, so
120 	 * remember that our pointer into the heap array is offset
121 	 * by one element.
122 	 */
123 	if (queue->queue_array != NULL) {
124 		queue->queue_array++;
125 		bcopy(queue->queue_array, new_array,
126 		      queue->entries * sizeof(cam_pinfo *));
127 		free(queue->queue_array, M_DEVBUF);
128 	}
129 	queue->queue_array = new_array-1;
130 	queue->array_size = new_size;
131 	return (CAM_REQ_CMP);
132 }
133 
134 /*
135  * camq_insert: Given an array of cam_pinfo* elememnts with
136  * the Heap(1, num_elements) property and array_size - num_elements >= 1,
137  * output Heap(1, num_elements+1) including new_entry in the array.
138  */
139 void
140 camq_insert(struct camq *queue, cam_pinfo *new_entry)
141 {
142 #ifdef DIAGNOSTIC
143 	if (queue->entries >= queue->array_size)
144 		panic("camq_insert: Attempt to insert into a full queue");
145 #endif
146 	queue->entries++;
147 	queue->queue_array[queue->entries] = new_entry;
148 	new_entry->index = queue->entries;
149 	if (queue->entries != 0)
150 		heap_up(queue->queue_array, queue->entries);
151 }
152 
153 /*
154  * camq_remove:  Given an array of cam_pinfo* elevements with the
155  * Heap(1, num_elements) property and an index such that 1 <= index <=
156  * num_elements, remove that entry and restore the Heap(1, num_elements-1)
157  * property.
158  */
159 cam_pinfo *
160 camq_remove(struct camq *queue, int index)
161 {
162 	cam_pinfo *removed_entry;
163 
164 	if (index == 0 || index > queue->entries)
165 		return (NULL);
166 	removed_entry = queue->queue_array[index];
167 	if (queue->entries != index) {
168 		queue->queue_array[index] = queue->queue_array[queue->entries];
169 		queue->queue_array[index]->index = index;
170 		heap_down(queue->queue_array, index, queue->entries - 1);
171 	}
172 	removed_entry->index = CAM_UNQUEUED_INDEX;
173 	queue->entries--;
174 	return (removed_entry);
175 }
176 
177 /*
178  * camq_change_priority:  Given an array of cam_pinfo* elements with the
179  * Heap(1, num_entries) property, an index such that 1 <= index <= num_elements,
180  * and an new priority for the element at index, change the priority of
181  * element index and restore the Heap(0, num_elements) property.
182  */
183 void
184 camq_change_priority(struct camq *queue, int index, u_int32_t new_priority)
185 {
186 	if (new_priority > queue->queue_array[index]->priority) {
187 		queue->queue_array[index]->priority = new_priority;
188 		heap_down(queue->queue_array, index, queue->entries);
189 	} else {
190 		/* new_priority <= old_priority */
191 		queue->queue_array[index]->priority = new_priority;
192 		heap_up(queue->queue_array, index);
193 	}
194 }
195 
196 struct cam_devq *
197 cam_devq_alloc(int devices, int openings)
198 {
199 	struct cam_devq *devq;
200 
201 	devq = malloc(sizeof(*devq), M_DEVBUF, M_INTWAIT);
202 	cam_devq_init(devq, devices, openings);
203 	return (devq);
204 }
205 
206 int
207 cam_devq_init(struct cam_devq *devq, int devices, int openings)
208 {
209 	bzero(devq, sizeof(*devq));
210 	camq_init(&devq->alloc_queue, devices);
211 	camq_init(&devq->send_queue, devices);
212 	devq->alloc_openings = openings;
213 	devq->alloc_active = 0;
214 	devq->send_openings = openings;
215 	devq->send_active = 0;
216 	return (0);
217 }
218 
219 void
220 cam_devq_free(struct cam_devq *devq)
221 {
222 	camq_fini(&devq->alloc_queue);
223 	camq_fini(&devq->send_queue);
224 	free(devq, M_DEVBUF);
225 }
226 
227 u_int32_t
228 cam_devq_resize(struct cam_devq *camq, int devices)
229 {
230 	u_int32_t retval;
231 
232 	retval = camq_resize(&camq->alloc_queue, devices);
233 
234 	if (retval == CAM_REQ_CMP)
235 		retval = camq_resize(&camq->send_queue, devices);
236 
237 	return (retval);
238 }
239 
240 struct cam_ccbq *
241 cam_ccbq_alloc(int openings)
242 {
243 	struct cam_ccbq *ccbq;
244 
245 	ccbq = malloc(sizeof(*ccbq), M_DEVBUF, M_INTWAIT);
246 	cam_ccbq_init(ccbq, openings);
247 	return (ccbq);
248 }
249 
250 void
251 cam_ccbq_free(struct cam_ccbq *ccbq)
252 {
253 	if (ccbq) {
254 		camq_fini(&ccbq->queue);
255 		free(ccbq, M_DEVBUF);
256 	}
257 }
258 
259 u_int32_t
260 cam_ccbq_resize(struct cam_ccbq *ccbq, int new_size)
261 {
262 	int delta;
263 	int space_left;
264 
265 	delta = new_size - (ccbq->dev_active + ccbq->dev_openings);
266 	space_left = new_size
267 	    - ccbq->queue.entries
268 	    - ccbq->held
269 	    - ccbq->dev_active;
270 
271 	/*
272 	 * Only attempt to change the underlying queue size if we are
273 	 * shrinking it and there is space for all outstanding entries
274 	 * in the new array or we have been requested to grow the array.
275 	 * We don't fail in the case where we can't reduce the array size,
276 	 * but clients that care that the queue be "garbage collected"
277 	 * should detect this condition and call us again with the
278 	 * same size once the outstanding entries have been processed.
279 	 */
280 	if (space_left < 0
281 	 || camq_resize(&ccbq->queue, new_size) == CAM_REQ_CMP) {
282 		ccbq->devq_openings += delta;
283 		ccbq->dev_openings += delta;
284 		return (CAM_REQ_CMP);
285 	} else {
286 		return (CAM_RESRC_UNAVAIL);
287 	}
288 }
289 
290 int
291 cam_ccbq_init(struct cam_ccbq *ccbq, int openings)
292 {
293 	bzero(ccbq, sizeof(*ccbq));
294 	camq_init(&ccbq->queue, openings);
295 	ccbq->devq_openings = openings;
296 	ccbq->dev_openings = openings;
297 	TAILQ_INIT(&ccbq->active_ccbs);
298 	return (0);
299 }
300 
301 /*
302  * Heap routines for manipulating CAM queues.
303  */
304 /*
305  * queue_cmp: Given an array of cam_pinfo* elements and indexes i
306  * and j, return less than 0, 0, or greater than 0 if i is less than,
307  * equal too, or greater than j respectively.
308  */
309 static __inline int
310 queue_cmp(cam_pinfo **queue_array, int i, int j)
311 {
312 	if (queue_array[i]->priority == queue_array[j]->priority)
313 		return (  queue_array[i]->generation
314 			- queue_array[j]->generation );
315 	else
316 		return (  queue_array[i]->priority
317 			- queue_array[j]->priority );
318 }
319 
320 /*
321  * swap: Given an array of cam_pinfo* elements and indexes i and j,
322  * exchange elements i and j.
323  */
324 static __inline void
325 swap(cam_pinfo **queue_array, int i, int j)
326 {
327 	cam_pinfo *temp_qentry;
328 
329 	temp_qentry = queue_array[j];
330 	queue_array[j] = queue_array[i];
331 	queue_array[i] = temp_qentry;
332 	queue_array[j]->index = j;
333 	queue_array[i]->index = i;
334 }
335 
336 /*
337  * heap_up:  Given an array of cam_pinfo* elements with the
338  * Heap(1, new_index-1) property and a new element in location
339  * new_index, output Heap(1, new_index).
340  */
341 static void
342 heap_up(cam_pinfo **queue_array, int new_index)
343 {
344 	int child;
345 	int parent;
346 
347 	child = new_index;
348 
349 	while (child != 1) {
350 
351 		parent = child >> 1;
352 		if (queue_cmp(queue_array, parent, child) <= 0)
353 			break;
354 		swap(queue_array, parent, child);
355 		child = parent;
356 	}
357 }
358 
359 /*
360  * heap_down:  Given an array of cam_pinfo* elements with the
361  * Heap(index + 1, num_entries) property with index containing
362  * an unsorted entry, output Heap(index, num_entries).
363  */
364 static void
365 heap_down(cam_pinfo **queue_array, int index, int num_entries)
366 {
367 	int child;
368 	int parent;
369 
370 	parent = index;
371 	child = parent << 1;
372 	for (; child <= num_entries; child = parent << 1) {
373 
374 		if (child < num_entries) {
375 			/* child+1 is the right child of parent */
376 			if (queue_cmp(queue_array, child + 1, child) < 0)
377 				child++;
378 		}
379 		/* child is now the least child of parent */
380 		if (queue_cmp(queue_array, parent, child) <= 0)
381 			break;
382 		swap(queue_array, child, parent);
383 		parent = child;
384 	}
385 }
386