ia64/linux-2.6.18-xen.hg

view drivers/block/swim_iop.c @ 897:329ea0ccb344

balloon: try harder to balloon up under memory pressure.

Currently if the balloon driver is unable to increase the guest's
reservation it assumes the failure was due to reaching its full
allocation, gives up on the ballooning operation and records the limit
it reached as the "hard limit". The driver will not try again until
the target is set again (even to the same value).

However it is possible that ballooning has in fact failed due to
memory pressure in the host and therefore it is desirable to keep
attempting to reach the target in case memory becomes available. The
most likely scenario is that some guests are ballooning down while
others are ballooning up and therefore there is temporary memory
pressure while things stabilise. You would not expect a well behaved
toolstack to ask a domain to balloon to more than its allocation nor
would you expect it to deliberately over-commit memory by setting
balloon targets which exceed the total host memory.

This patch drops the concept of a hard limit and causes the balloon
driver to retry increasing the reservation on a timer in the same
manner as when decreasing the reservation.

Also if we partially succeed in increasing the reservation
(i.e. receive less pages than we asked for) then we may as well keep
those pages rather than returning them to Xen.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Fri Jun 05 14:01:20 2009 +0100 (2009-06-05)
parents 831230e53067
children
line source
1 /*
2 * Driver for the SWIM (Super Woz Integrated Machine) IOP
3 * floppy controller on the Macintosh IIfx and Quadra 900/950
4 *
5 * Written by Joshua M. Thompson (funaho@jurai.org)
6 * based on the SWIM3 driver (c) 1996 by Paul Mackerras.
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
12 *
13 * 1999-06-12 (jmt) - Initial implementation.
14 */
16 /*
17 * -------------------
18 * Theory of Operation
19 * -------------------
20 *
21 * Since the SWIM IOP is message-driven we implement a simple request queue
22 * system. One outstanding request may be queued at any given time (this is
23 * an IOP limitation); only when that request has completed can a new request
24 * be sent.
25 */
27 #include <linux/stddef.h>
28 #include <linux/kernel.h>
29 #include <linux/sched.h>
30 #include <linux/timer.h>
31 #include <linux/delay.h>
32 #include <linux/fd.h>
33 #include <linux/ioctl.h>
34 #include <linux/blkdev.h>
35 #include <asm/io.h>
36 #include <asm/uaccess.h>
37 #include <asm/mac_iop.h>
38 #include <asm/swim_iop.h>
40 #define DRIVER_VERSION "Version 0.1 (1999-06-12)"
42 #define MAX_FLOPPIES 4
44 enum swim_state {
45 idle,
46 available,
47 revalidating,
48 transferring,
49 ejecting
50 };
52 struct floppy_state {
53 enum swim_state state;
54 int drive_num; /* device number */
55 int secpercyl; /* disk geometry information */
56 int secpertrack;
57 int total_secs;
58 int write_prot; /* 1 if write-protected, 0 if not, -1 dunno */
59 int ref_count;
60 struct timer_list timeout;
61 int ejected;
62 struct wait_queue *wait;
63 int wanted;
64 int timeout_pending;
65 };
67 struct swim_iop_req {
68 int sent;
69 int complete;
70 __u8 command[32];
71 struct floppy_state *fs;
72 void (*done)(struct swim_iop_req *);
73 };
75 static struct swim_iop_req *current_req;
76 static int floppy_count;
78 static struct floppy_state floppy_states[MAX_FLOPPIES];
79 static DEFINE_SPINLOCK(swim_iop_lock);
81 #define CURRENT elv_next_request(swim_queue)
83 static char *drive_names[7] = {
84 "not installed", /* DRV_NONE */
85 "unknown (1)", /* DRV_UNKNOWN */
86 "a 400K drive", /* DRV_400K */
87 "an 800K drive" /* DRV_800K */
88 "unknown (4)", /* ???? */
89 "an FDHD", /* DRV_FDHD */
90 "unknown (6)", /* ???? */
91 "an Apple HD20" /* DRV_HD20 */
92 };
94 int swimiop_init(void);
95 static void swimiop_init_request(struct swim_iop_req *);
96 static int swimiop_send_request(struct swim_iop_req *);
97 static void swimiop_receive(struct iop_msg *, struct pt_regs *);
98 static void swimiop_status_update(int, struct swim_drvstatus *);
99 static int swimiop_eject(struct floppy_state *fs);
101 static int floppy_ioctl(struct inode *inode, struct file *filp,
102 unsigned int cmd, unsigned long param);
103 static int floppy_open(struct inode *inode, struct file *filp);
104 static int floppy_release(struct inode *inode, struct file *filp);
105 static int floppy_check_change(struct gendisk *disk);
106 static int floppy_revalidate(struct gendisk *disk);
107 static int grab_drive(struct floppy_state *fs, enum swim_state state,
108 int interruptible);
109 static void release_drive(struct floppy_state *fs);
110 static void set_timeout(struct floppy_state *fs, int nticks,
111 void (*proc)(unsigned long));
112 static void fd_request_timeout(unsigned long);
113 static void do_fd_request(request_queue_t * q);
114 static void start_request(struct floppy_state *fs);
116 static struct block_device_operations floppy_fops = {
117 .open = floppy_open,
118 .release = floppy_release,
119 .ioctl = floppy_ioctl,
120 .media_changed = floppy_check_change,
121 .revalidate_disk= floppy_revalidate,
122 };
124 static struct request_queue *swim_queue;
125 /*
126 * SWIM IOP initialization
127 */
129 int swimiop_init(void)
130 {
131 volatile struct swim_iop_req req;
132 struct swimcmd_status *cmd = (struct swimcmd_status *) &req.command[0];
133 struct swim_drvstatus *ds = &cmd->status;
134 struct floppy_state *fs;
135 int i;
137 current_req = NULL;
138 floppy_count = 0;
140 if (!iop_ism_present)
141 return -ENODEV;
143 if (register_blkdev(FLOPPY_MAJOR, "fd"))
144 return -EBUSY;
146 swim_queue = blk_init_queue(do_fd_request, &swim_iop_lock);
147 if (!swim_queue) {
148 unregister_blkdev(FLOPPY_MAJOR, "fd");
149 return -ENOMEM;
150 }
152 printk("SWIM-IOP: %s by Joshua M. Thompson (funaho@jurai.org)\n",
153 DRIVER_VERSION);
155 if (iop_listen(SWIM_IOP, SWIM_CHAN, swimiop_receive, "SWIM") != 0) {
156 printk(KERN_ERR "SWIM-IOP: IOP channel already in use; can't initialize.\n");
157 unregister_blkdev(FLOPPY_MAJOR, "fd");
158 blk_cleanup_queue(swim_queue);
159 return -EBUSY;
160 }
162 printk(KERN_ERR "SWIM_IOP: probing for installed drives.\n");
164 for (i = 0 ; i < MAX_FLOPPIES ; i++) {
165 memset(&floppy_states[i], 0, sizeof(struct floppy_state));
166 fs = &floppy_states[floppy_count];
168 swimiop_init_request(&req);
169 cmd->code = CMD_STATUS;
170 cmd->drive_num = i + 1;
171 if (swimiop_send_request(&req) != 0) continue;
172 while (!req.complete);
173 if (cmd->error != 0) {
174 printk(KERN_ERR "SWIM-IOP: probe on drive %d returned error %d\n", i, (uint) cmd->error);
175 continue;
176 }
177 if (ds->installed != 0x01) continue;
178 printk("SWIM-IOP: drive %d is %s (%s, %s, %s, %s)\n", i,
179 drive_names[ds->info.type],
180 ds->info.external? "ext" : "int",
181 ds->info.scsi? "scsi" : "floppy",
182 ds->info.fixed? "fixed" : "removable",
183 ds->info.secondary? "secondary" : "primary");
184 swimiop_status_update(floppy_count, ds);
185 fs->state = idle;
187 init_timer(&fs->timeout);
188 floppy_count++;
189 }
190 printk("SWIM-IOP: detected %d installed drives.\n", floppy_count);
192 for (i = 0; i < floppy_count; i++) {
193 struct gendisk *disk = alloc_disk(1);
194 if (!disk)
195 continue;
196 disk->major = FLOPPY_MAJOR;
197 disk->first_minor = i;
198 disk->fops = &floppy_fops;
199 sprintf(disk->disk_name, "fd%d", i);
200 disk->private_data = &floppy_states[i];
201 disk->queue = swim_queue;
202 set_capacity(disk, 2880 * 2);
203 add_disk(disk);
204 }
206 return 0;
207 }
209 static void swimiop_init_request(struct swim_iop_req *req)
210 {
211 req->sent = 0;
212 req->complete = 0;
213 req->done = NULL;
214 }
216 static int swimiop_send_request(struct swim_iop_req *req)
217 {
218 unsigned long flags;
219 int err;
221 /* It's doubtful an interrupt routine would try to send */
222 /* a SWIM request, but I'd rather play it safe here. */
224 local_irq_save(flags);
226 if (current_req != NULL) {
227 local_irq_restore(flags);
228 return -ENOMEM;
229 }
231 current_req = req;
233 /* Interrupts should be back on for iop_send_message() */
235 local_irq_restore(flags);
237 err = iop_send_message(SWIM_IOP, SWIM_CHAN, (void *) req,
238 sizeof(req->command), (__u8 *) &req->command[0],
239 swimiop_receive);
241 /* No race condition here; we own current_req at this point */
243 if (err) {
244 current_req = NULL;
245 } else {
246 req->sent = 1;
247 }
248 return err;
249 }
251 /*
252 * Receive a SWIM message from the IOP.
253 *
254 * This will be called in two cases:
255 *
256 * 1. A message has been successfully sent to the IOP.
257 * 2. An unsolicited message was received from the IOP.
258 */
260 void swimiop_receive(struct iop_msg *msg, struct pt_regs *regs)
261 {
262 struct swim_iop_req *req;
263 struct swimmsg_status *sm;
264 struct swim_drvstatus *ds;
266 req = current_req;
268 switch(msg->status) {
269 case IOP_MSGSTATUS_COMPLETE:
270 memcpy(&req->command[0], &msg->reply[0], sizeof(req->command));
271 req->complete = 1;
272 if (req->done) (*req->done)(req);
273 current_req = NULL;
274 break;
275 case IOP_MSGSTATUS_UNSOL:
276 sm = (struct swimmsg_status *) &msg->message[0];
277 ds = &sm->status;
278 swimiop_status_update(sm->drive_num, ds);
279 iop_complete_message(msg);
280 break;
281 }
282 }
284 static void swimiop_status_update(int drive_num, struct swim_drvstatus *ds)
285 {
286 struct floppy_state *fs = &floppy_states[drive_num];
288 fs->write_prot = (ds->write_prot == 0x80);
289 if ((ds->disk_in_drive != 0x01) && (ds->disk_in_drive != 0x02)) {
290 fs->ejected = 1;
291 } else {
292 fs->ejected = 0;
293 }
294 switch(ds->info.type) {
295 case DRV_400K:
296 fs->secpercyl = 10;
297 fs->secpertrack = 10;
298 fs->total_secs = 800;
299 break;
300 case DRV_800K:
301 fs->secpercyl = 20;
302 fs->secpertrack = 10;
303 fs->total_secs = 1600;
304 break;
305 case DRV_FDHD:
306 fs->secpercyl = 36;
307 fs->secpertrack = 18;
308 fs->total_secs = 2880;
309 break;
310 default:
311 fs->secpercyl = 0;
312 fs->secpertrack = 0;
313 fs->total_secs = 0;
314 break;
315 }
316 }
318 static int swimiop_eject(struct floppy_state *fs)
319 {
320 int err, n;
321 struct swim_iop_req req;
322 struct swimcmd_eject *cmd = (struct swimcmd_eject *) &req.command[0];
324 err = grab_drive(fs, ejecting, 1);
325 if (err) return err;
327 swimiop_init_request(&req);
328 cmd->code = CMD_EJECT;
329 cmd->drive_num = fs->drive_num;
330 err = swimiop_send_request(&req);
331 if (err) {
332 release_drive(fs);
333 return err;
334 }
335 for (n = 2*HZ; n > 0; --n) {
336 if (req.complete) break;
337 if (signal_pending(current)) {
338 err = -EINTR;
339 break;
340 }
341 schedule_timeout_interruptible(1);
342 }
343 release_drive(fs);
344 return cmd->error;
345 }
347 static struct floppy_struct floppy_type =
348 { 2880,18,2,80,0,0x1B,0x00,0xCF,0x6C,NULL }; /* 7 1.44MB 3.5" */
350 static int floppy_ioctl(struct inode *inode, struct file *filp,
351 unsigned int cmd, unsigned long param)
352 {
353 struct floppy_state *fs = inode->i_bdev->bd_disk->private_data;
354 int err;
356 if ((cmd & 0x80) && !capable(CAP_SYS_ADMIN))
357 return -EPERM;
359 switch (cmd) {
360 case FDEJECT:
361 if (fs->ref_count != 1)
362 return -EBUSY;
363 err = swimiop_eject(fs);
364 return err;
365 case FDGETPRM:
366 if (copy_to_user((void *) param, (void *) &floppy_type,
367 sizeof(struct floppy_struct)))
368 return -EFAULT;
369 return 0;
370 }
371 return -ENOTTY;
372 }
374 static int floppy_open(struct inode *inode, struct file *filp)
375 {
376 struct floppy_state *fs = inode->i_bdev->bd_disk->private_data;
378 if (fs->ref_count == -1 || filp->f_flags & O_EXCL)
379 return -EBUSY;
381 if ((filp->f_flags & O_NDELAY) == 0 && (filp->f_mode & 3)) {
382 check_disk_change(inode->i_bdev);
383 if (fs->ejected)
384 return -ENXIO;
385 }
387 if ((filp->f_mode & 2) && fs->write_prot)
388 return -EROFS;
390 if (filp->f_flags & O_EXCL)
391 fs->ref_count = -1;
392 else
393 ++fs->ref_count;
395 return 0;
396 }
398 static int floppy_release(struct inode *inode, struct file *filp)
399 {
400 struct floppy_state *fs = inode->i_bdev->bd_disk->private_data;
401 if (fs->ref_count > 0)
402 fs->ref_count--;
403 return 0;
404 }
406 static int floppy_check_change(struct gendisk *disk)
407 {
408 struct floppy_state *fs = disk->private_data;
409 return fs->ejected;
410 }
412 static int floppy_revalidate(struct gendisk *disk)
413 {
414 struct floppy_state *fs = disk->private_data;
415 grab_drive(fs, revalidating, 0);
416 /* yadda, yadda */
417 release_drive(fs);
418 return 0;
419 }
421 static void floppy_off(unsigned int nr)
422 {
423 }
425 static int grab_drive(struct floppy_state *fs, enum swim_state state,
426 int interruptible)
427 {
428 unsigned long flags;
430 local_irq_save(flags);
431 if (fs->state != idle) {
432 ++fs->wanted;
433 while (fs->state != available) {
434 if (interruptible && signal_pending(current)) {
435 --fs->wanted;
436 local_irq_restore(flags);
437 return -EINTR;
438 }
439 interruptible_sleep_on(&fs->wait);
440 }
441 --fs->wanted;
442 }
443 fs->state = state;
444 local_irq_restore(flags);
445 return 0;
446 }
448 static void release_drive(struct floppy_state *fs)
449 {
450 unsigned long flags;
452 local_irq_save(flags);
453 fs->state = idle;
454 start_request(fs);
455 local_irq_restore(flags);
456 }
458 static void set_timeout(struct floppy_state *fs, int nticks,
459 void (*proc)(unsigned long))
460 {
461 unsigned long flags;
463 local_irq_save(flags);
464 if (fs->timeout_pending)
465 del_timer(&fs->timeout);
466 init_timer(&fs->timeout);
467 fs->timeout.expires = jiffies + nticks;
468 fs->timeout.function = proc;
469 fs->timeout.data = (unsigned long) fs;
470 add_timer(&fs->timeout);
471 fs->timeout_pending = 1;
472 local_irq_restore(flags);
473 }
475 static void do_fd_request(request_queue_t * q)
476 {
477 int i;
479 for (i = 0 ; i < floppy_count ; i++) {
480 start_request(&floppy_states[i]);
481 }
482 }
484 static void fd_request_complete(struct swim_iop_req *req)
485 {
486 struct floppy_state *fs = req->fs;
487 struct swimcmd_rw *cmd = (struct swimcmd_rw *) &req->command[0];
489 del_timer(&fs->timeout);
490 fs->timeout_pending = 0;
491 fs->state = idle;
492 if (cmd->error) {
493 printk(KERN_ERR "SWIM-IOP: error %d on read/write request.\n", cmd->error);
494 end_request(CURRENT, 0);
495 } else {
496 CURRENT->sector += cmd->num_blocks;
497 CURRENT->current_nr_sectors -= cmd->num_blocks;
498 if (CURRENT->current_nr_sectors <= 0) {
499 end_request(CURRENT, 1);
500 return;
501 }
502 }
503 start_request(fs);
504 }
506 static void fd_request_timeout(unsigned long data)
507 {
508 struct floppy_state *fs = (struct floppy_state *) data;
510 fs->timeout_pending = 0;
511 end_request(CURRENT, 0);
512 fs->state = idle;
513 }
515 static void start_request(struct floppy_state *fs)
516 {
517 volatile struct swim_iop_req req;
518 struct swimcmd_rw *cmd = (struct swimcmd_rw *) &req.command[0];
520 if (fs->state == idle && fs->wanted) {
521 fs->state = available;
522 wake_up(&fs->wait);
523 return;
524 }
525 while (CURRENT && fs->state == idle) {
526 if (CURRENT->bh && !buffer_locked(CURRENT->bh))
527 panic("floppy: block not locked");
528 #if 0
529 printk("do_fd_req: dev=%s cmd=%d sec=%ld nr_sec=%ld buf=%p\n",
530 CURRENT->rq_disk->disk_name, CURRENT->cmd,
531 CURRENT->sector, CURRENT->nr_sectors, CURRENT->buffer);
532 printk(" rq_status=%d errors=%d current_nr_sectors=%ld\n",
533 CURRENT->rq_status, CURRENT->errors, CURRENT->current_nr_sectors);
534 #endif
536 if (CURRENT->sector < 0 || CURRENT->sector >= fs->total_secs) {
537 end_request(CURRENT, 0);
538 continue;
539 }
540 if (CURRENT->current_nr_sectors == 0) {
541 end_request(CURRENT, 1);
542 continue;
543 }
544 if (fs->ejected) {
545 end_request(CURRENT, 0);
546 continue;
547 }
549 swimiop_init_request(&req);
550 req.fs = fs;
551 req.done = fd_request_complete;
553 if (CURRENT->cmd == WRITE) {
554 if (fs->write_prot) {
555 end_request(CURRENT, 0);
556 continue;
557 }
558 cmd->code = CMD_WRITE;
559 } else {
560 cmd->code = CMD_READ;
562 }
563 cmd->drive_num = fs->drive_num;
564 cmd->buffer = CURRENT->buffer;
565 cmd->first_block = CURRENT->sector;
566 cmd->num_blocks = CURRENT->current_nr_sectors;
568 if (swimiop_send_request(&req)) {
569 end_request(CURRENT, 0);
570 continue;
571 }
573 set_timeout(fs, HZ*CURRENT->current_nr_sectors,
574 fd_request_timeout);
576 fs->state = transferring;
577 }
578 }