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1775826c JF |
1 | /****************************************************************************** |
2 | * balloon.c | |
3 | * | |
4 | * Xen balloon driver - enables returning/claiming memory to/from Xen. | |
5 | * | |
6 | * Copyright (c) 2003, B Dragovic | |
7 | * Copyright (c) 2003-2004, M Williamson, K Fraser | |
8 | * Copyright (c) 2005 Dan M. Smith, IBM Corporation | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or | |
11 | * modify it under the terms of the GNU General Public License version 2 | |
12 | * as published by the Free Software Foundation; or, when distributed | |
13 | * separately from the Linux kernel or incorporated into other | |
14 | * software packages, subject to the following license: | |
15 | * | |
16 | * Permission is hereby granted, free of charge, to any person obtaining a copy | |
17 | * of this source file (the "Software"), to deal in the Software without | |
18 | * restriction, including without limitation the rights to use, copy, modify, | |
19 | * merge, publish, distribute, sublicense, and/or sell copies of the Software, | |
20 | * and to permit persons to whom the Software is furnished to do so, subject to | |
21 | * the following conditions: | |
22 | * | |
23 | * The above copyright notice and this permission notice shall be included in | |
24 | * all copies or substantial portions of the Software. | |
25 | * | |
26 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
27 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
28 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
29 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
30 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING | |
31 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS | |
32 | * IN THE SOFTWARE. | |
33 | */ | |
34 | ||
35 | #include <linux/kernel.h> | |
36 | #include <linux/module.h> | |
37 | #include <linux/sched.h> | |
38 | #include <linux/errno.h> | |
39 | #include <linux/mm.h> | |
40 | #include <linux/bootmem.h> | |
41 | #include <linux/pagemap.h> | |
42 | #include <linux/highmem.h> | |
43 | #include <linux/mutex.h> | |
1775826c JF |
44 | #include <linux/list.h> |
45 | #include <linux/sysdev.h> | |
5a0e3ad6 | 46 | #include <linux/gfp.h> |
1775826c | 47 | |
1775826c JF |
48 | #include <asm/page.h> |
49 | #include <asm/pgalloc.h> | |
50 | #include <asm/pgtable.h> | |
51 | #include <asm/uaccess.h> | |
52 | #include <asm/tlb.h> | |
53 | ||
ecbf29cd JF |
54 | #include <asm/xen/hypervisor.h> |
55 | #include <asm/xen/hypercall.h> | |
1ccbf534 JF |
56 | |
57 | #include <xen/xen.h> | |
ecbf29cd | 58 | #include <xen/interface/xen.h> |
1775826c | 59 | #include <xen/interface/memory.h> |
1775826c JF |
60 | #include <xen/xenbus.h> |
61 | #include <xen/features.h> | |
62 | #include <xen/page.h> | |
63 | ||
64 | #define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10)) | |
65 | ||
167e6cf6 | 66 | #define BALLOON_CLASS_NAME "xen_memory" |
1775826c JF |
67 | |
68 | struct balloon_stats { | |
69 | /* We aim for 'current allocation' == 'target allocation'. */ | |
70 | unsigned long current_pages; | |
71 | unsigned long target_pages; | |
1775826c JF |
72 | /* |
73 | * Drivers may alter the memory reservation independently, but they | |
74 | * must inform the balloon driver so we avoid hitting the hard limit. | |
75 | */ | |
76 | unsigned long driver_pages; | |
77 | /* Number of pages in high- and low-memory balloons. */ | |
78 | unsigned long balloon_low; | |
79 | unsigned long balloon_high; | |
80 | }; | |
81 | ||
82 | static DEFINE_MUTEX(balloon_mutex); | |
83 | ||
84 | static struct sys_device balloon_sysdev; | |
85 | ||
86 | static int register_balloon(struct sys_device *sysdev); | |
87 | ||
1775826c JF |
88 | static struct balloon_stats balloon_stats; |
89 | ||
90 | /* We increase/decrease in batches which fit in a page */ | |
91 | static unsigned long frame_list[PAGE_SIZE / sizeof(unsigned long)]; | |
92 | ||
1775826c | 93 | #ifdef CONFIG_HIGHMEM |
1775826c JF |
94 | #define inc_totalhigh_pages() (totalhigh_pages++) |
95 | #define dec_totalhigh_pages() (totalhigh_pages--) | |
96 | #else | |
97 | #define inc_totalhigh_pages() do {} while(0) | |
98 | #define dec_totalhigh_pages() do {} while(0) | |
99 | #endif | |
100 | ||
101 | /* List of ballooned pages, threaded through the mem_map array. */ | |
102 | static LIST_HEAD(ballooned_pages); | |
103 | ||
104 | /* Main work function, always executed in process context. */ | |
105 | static void balloon_process(struct work_struct *work); | |
106 | static DECLARE_WORK(balloon_worker, balloon_process); | |
107 | static struct timer_list balloon_timer; | |
108 | ||
109 | /* When ballooning out (allocating memory to return to Xen) we don't really | |
110 | want the kernel to try too hard since that can trigger the oom killer. */ | |
111 | #define GFP_BALLOON \ | |
112 | (GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC) | |
113 | ||
114 | static void scrub_page(struct page *page) | |
115 | { | |
116 | #ifdef CONFIG_XEN_SCRUB_PAGES | |
26a3e991 | 117 | clear_highpage(page); |
1775826c JF |
118 | #endif |
119 | } | |
120 | ||
121 | /* balloon_append: add the given page to the balloon. */ | |
122 | static void balloon_append(struct page *page) | |
123 | { | |
124 | /* Lowmem is re-populated first, so highmem pages go at list tail. */ | |
125 | if (PageHighMem(page)) { | |
126 | list_add_tail(&page->lru, &ballooned_pages); | |
127 | balloon_stats.balloon_high++; | |
128 | dec_totalhigh_pages(); | |
129 | } else { | |
130 | list_add(&page->lru, &ballooned_pages); | |
131 | balloon_stats.balloon_low++; | |
132 | } | |
3d65c948 GG |
133 | |
134 | totalram_pages--; | |
1775826c JF |
135 | } |
136 | ||
137 | /* balloon_retrieve: rescue a page from the balloon, if it is not empty. */ | |
138 | static struct page *balloon_retrieve(void) | |
139 | { | |
140 | struct page *page; | |
141 | ||
142 | if (list_empty(&ballooned_pages)) | |
143 | return NULL; | |
144 | ||
145 | page = list_entry(ballooned_pages.next, struct page, lru); | |
146 | list_del(&page->lru); | |
147 | ||
148 | if (PageHighMem(page)) { | |
149 | balloon_stats.balloon_high--; | |
150 | inc_totalhigh_pages(); | |
151 | } | |
152 | else | |
153 | balloon_stats.balloon_low--; | |
154 | ||
3d65c948 GG |
155 | totalram_pages++; |
156 | ||
1775826c JF |
157 | return page; |
158 | } | |
159 | ||
160 | static struct page *balloon_first_page(void) | |
161 | { | |
162 | if (list_empty(&ballooned_pages)) | |
163 | return NULL; | |
164 | return list_entry(ballooned_pages.next, struct page, lru); | |
165 | } | |
166 | ||
167 | static struct page *balloon_next_page(struct page *page) | |
168 | { | |
169 | struct list_head *next = page->lru.next; | |
170 | if (next == &ballooned_pages) | |
171 | return NULL; | |
172 | return list_entry(next, struct page, lru); | |
173 | } | |
174 | ||
175 | static void balloon_alarm(unsigned long unused) | |
176 | { | |
177 | schedule_work(&balloon_worker); | |
178 | } | |
179 | ||
180 | static unsigned long current_target(void) | |
181 | { | |
bc2c0303 | 182 | unsigned long target = balloon_stats.target_pages; |
1775826c JF |
183 | |
184 | target = min(target, | |
185 | balloon_stats.current_pages + | |
186 | balloon_stats.balloon_low + | |
187 | balloon_stats.balloon_high); | |
188 | ||
189 | return target; | |
190 | } | |
191 | ||
192 | static int increase_reservation(unsigned long nr_pages) | |
193 | { | |
194 | unsigned long pfn, i, flags; | |
195 | struct page *page; | |
196 | long rc; | |
197 | struct xen_memory_reservation reservation = { | |
198 | .address_bits = 0, | |
199 | .extent_order = 0, | |
200 | .domid = DOMID_SELF | |
201 | }; | |
202 | ||
203 | if (nr_pages > ARRAY_SIZE(frame_list)) | |
204 | nr_pages = ARRAY_SIZE(frame_list); | |
205 | ||
19001c8c | 206 | spin_lock_irqsave(&xen_reservation_lock, flags); |
1775826c JF |
207 | |
208 | page = balloon_first_page(); | |
209 | for (i = 0; i < nr_pages; i++) { | |
210 | BUG_ON(page == NULL); | |
a419aef8 | 211 | frame_list[i] = page_to_pfn(page); |
1775826c JF |
212 | page = balloon_next_page(page); |
213 | } | |
214 | ||
a90971eb | 215 | set_xen_guest_handle(reservation.extent_start, frame_list); |
fde28e8f JF |
216 | reservation.nr_extents = nr_pages; |
217 | rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation); | |
bc2c0303 | 218 | if (rc < 0) |
1775826c | 219 | goto out; |
1775826c | 220 | |
bc2c0303 | 221 | for (i = 0; i < rc; i++) { |
1775826c JF |
222 | page = balloon_retrieve(); |
223 | BUG_ON(page == NULL); | |
224 | ||
225 | pfn = page_to_pfn(page); | |
226 | BUG_ON(!xen_feature(XENFEAT_auto_translated_physmap) && | |
227 | phys_to_machine_mapping_valid(pfn)); | |
228 | ||
229 | set_phys_to_machine(pfn, frame_list[i]); | |
230 | ||
231 | /* Link back into the page tables if not highmem. */ | |
232 | if (pfn < max_low_pfn) { | |
233 | int ret; | |
234 | ret = HYPERVISOR_update_va_mapping( | |
235 | (unsigned long)__va(pfn << PAGE_SHIFT), | |
236 | mfn_pte(frame_list[i], PAGE_KERNEL), | |
237 | 0); | |
238 | BUG_ON(ret); | |
239 | } | |
240 | ||
241 | /* Relinquish the page back to the allocator. */ | |
242 | ClearPageReserved(page); | |
243 | init_page_count(page); | |
244 | __free_page(page); | |
245 | } | |
246 | ||
bc2c0303 | 247 | balloon_stats.current_pages += rc; |
1775826c JF |
248 | |
249 | out: | |
19001c8c | 250 | spin_unlock_irqrestore(&xen_reservation_lock, flags); |
1775826c | 251 | |
bc2c0303 | 252 | return rc < 0 ? rc : rc != nr_pages; |
1775826c JF |
253 | } |
254 | ||
255 | static int decrease_reservation(unsigned long nr_pages) | |
256 | { | |
257 | unsigned long pfn, i, flags; | |
258 | struct page *page; | |
259 | int need_sleep = 0; | |
260 | int ret; | |
261 | struct xen_memory_reservation reservation = { | |
262 | .address_bits = 0, | |
263 | .extent_order = 0, | |
264 | .domid = DOMID_SELF | |
265 | }; | |
266 | ||
267 | if (nr_pages > ARRAY_SIZE(frame_list)) | |
268 | nr_pages = ARRAY_SIZE(frame_list); | |
269 | ||
270 | for (i = 0; i < nr_pages; i++) { | |
271 | if ((page = alloc_page(GFP_BALLOON)) == NULL) { | |
272 | nr_pages = i; | |
273 | need_sleep = 1; | |
274 | break; | |
275 | } | |
276 | ||
277 | pfn = page_to_pfn(page); | |
278 | frame_list[i] = pfn_to_mfn(pfn); | |
279 | ||
280 | scrub_page(page); | |
1058a75f | 281 | |
ff4ce8c3 IC |
282 | if (!PageHighMem(page)) { |
283 | ret = HYPERVISOR_update_va_mapping( | |
284 | (unsigned long)__va(pfn << PAGE_SHIFT), | |
285 | __pte_ma(0), 0); | |
286 | BUG_ON(ret); | |
287 | } | |
288 | ||
1775826c JF |
289 | } |
290 | ||
291 | /* Ensure that ballooned highmem pages don't have kmaps. */ | |
292 | kmap_flush_unused(); | |
293 | flush_tlb_all(); | |
294 | ||
19001c8c | 295 | spin_lock_irqsave(&xen_reservation_lock, flags); |
1775826c JF |
296 | |
297 | /* No more mappings: invalidate P2M and add to balloon. */ | |
298 | for (i = 0; i < nr_pages; i++) { | |
299 | pfn = mfn_to_pfn(frame_list[i]); | |
300 | set_phys_to_machine(pfn, INVALID_P2M_ENTRY); | |
301 | balloon_append(pfn_to_page(pfn)); | |
302 | } | |
303 | ||
a90971eb | 304 | set_xen_guest_handle(reservation.extent_start, frame_list); |
1775826c JF |
305 | reservation.nr_extents = nr_pages; |
306 | ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation); | |
307 | BUG_ON(ret != nr_pages); | |
308 | ||
309 | balloon_stats.current_pages -= nr_pages; | |
1775826c | 310 | |
19001c8c | 311 | spin_unlock_irqrestore(&xen_reservation_lock, flags); |
1775826c JF |
312 | |
313 | return need_sleep; | |
314 | } | |
315 | ||
316 | /* | |
317 | * We avoid multiple worker processes conflicting via the balloon mutex. | |
318 | * We may of course race updates of the target counts (which are protected | |
319 | * by the balloon lock), or with changes to the Xen hard limit, but we will | |
320 | * recover from these in time. | |
321 | */ | |
322 | static void balloon_process(struct work_struct *work) | |
323 | { | |
324 | int need_sleep = 0; | |
325 | long credit; | |
326 | ||
327 | mutex_lock(&balloon_mutex); | |
328 | ||
329 | do { | |
330 | credit = current_target() - balloon_stats.current_pages; | |
331 | if (credit > 0) | |
332 | need_sleep = (increase_reservation(credit) != 0); | |
333 | if (credit < 0) | |
334 | need_sleep = (decrease_reservation(-credit) != 0); | |
335 | ||
336 | #ifndef CONFIG_PREEMPT | |
337 | if (need_resched()) | |
338 | schedule(); | |
339 | #endif | |
340 | } while ((credit != 0) && !need_sleep); | |
341 | ||
342 | /* Schedule more work if there is some still to be done. */ | |
343 | if (current_target() != balloon_stats.current_pages) | |
344 | mod_timer(&balloon_timer, jiffies + HZ); | |
345 | ||
346 | mutex_unlock(&balloon_mutex); | |
347 | } | |
348 | ||
349 | /* Resets the Xen limit, sets new target, and kicks off processing. */ | |
955d6f17 | 350 | static void balloon_set_new_target(unsigned long target) |
1775826c JF |
351 | { |
352 | /* No need for lock. Not read-modify-write updates. */ | |
1775826c JF |
353 | balloon_stats.target_pages = target; |
354 | schedule_work(&balloon_worker); | |
355 | } | |
356 | ||
357 | static struct xenbus_watch target_watch = | |
358 | { | |
359 | .node = "memory/target" | |
360 | }; | |
361 | ||
362 | /* React to a change in the target key */ | |
363 | static void watch_target(struct xenbus_watch *watch, | |
364 | const char **vec, unsigned int len) | |
365 | { | |
366 | unsigned long long new_target; | |
367 | int err; | |
368 | ||
369 | err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target); | |
370 | if (err != 1) { | |
371 | /* This is ok (for domain0 at least) - so just return */ | |
372 | return; | |
373 | } | |
374 | ||
375 | /* The given memory/target value is in KiB, so it needs converting to | |
376 | * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10. | |
377 | */ | |
378 | balloon_set_new_target(new_target >> (PAGE_SHIFT - 10)); | |
379 | } | |
380 | ||
381 | static int balloon_init_watcher(struct notifier_block *notifier, | |
382 | unsigned long event, | |
383 | void *data) | |
384 | { | |
385 | int err; | |
386 | ||
387 | err = register_xenbus_watch(&target_watch); | |
388 | if (err) | |
389 | printk(KERN_ERR "Failed to set balloon watcher\n"); | |
390 | ||
391 | return NOTIFY_DONE; | |
392 | } | |
393 | ||
394 | static struct notifier_block xenstore_notifier; | |
395 | ||
396 | static int __init balloon_init(void) | |
397 | { | |
398 | unsigned long pfn; | |
399 | struct page *page; | |
400 | ||
6e833587 | 401 | if (!xen_pv_domain()) |
1775826c JF |
402 | return -ENODEV; |
403 | ||
404 | pr_info("xen_balloon: Initialising balloon driver.\n"); | |
405 | ||
406 | balloon_stats.current_pages = min(xen_start_info->nr_pages, max_pfn); | |
1775826c JF |
407 | balloon_stats.target_pages = balloon_stats.current_pages; |
408 | balloon_stats.balloon_low = 0; | |
409 | balloon_stats.balloon_high = 0; | |
410 | balloon_stats.driver_pages = 0UL; | |
1775826c JF |
411 | |
412 | init_timer(&balloon_timer); | |
413 | balloon_timer.data = 0; | |
414 | balloon_timer.function = balloon_alarm; | |
415 | ||
416 | register_balloon(&balloon_sysdev); | |
417 | ||
418 | /* Initialise the balloon with excess memory space. */ | |
419 | for (pfn = xen_start_info->nr_pages; pfn < max_pfn; pfn++) { | |
420 | page = pfn_to_page(pfn); | |
421 | if (!PageReserved(page)) | |
422 | balloon_append(page); | |
423 | } | |
424 | ||
425 | target_watch.callback = watch_target; | |
426 | xenstore_notifier.notifier_call = balloon_init_watcher; | |
427 | ||
428 | register_xenstore_notifier(&xenstore_notifier); | |
429 | ||
430 | return 0; | |
431 | } | |
432 | ||
433 | subsys_initcall(balloon_init); | |
434 | ||
435 | static void balloon_exit(void) | |
436 | { | |
437 | /* XXX - release balloon here */ | |
438 | return; | |
439 | } | |
440 | ||
441 | module_exit(balloon_exit); | |
442 | ||
167e6cf6 JF |
443 | #define BALLOON_SHOW(name, format, args...) \ |
444 | static ssize_t show_##name(struct sys_device *dev, \ | |
445 | struct sysdev_attribute *attr, \ | |
446 | char *buf) \ | |
447 | { \ | |
448 | return sprintf(buf, format, ##args); \ | |
449 | } \ | |
1775826c JF |
450 | static SYSDEV_ATTR(name, S_IRUGO, show_##name, NULL) |
451 | ||
452 | BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages)); | |
453 | BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low)); | |
454 | BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high)); | |
1775826c JF |
455 | BALLOON_SHOW(driver_kb, "%lu\n", PAGES2KB(balloon_stats.driver_pages)); |
456 | ||
167e6cf6 JF |
457 | static ssize_t show_target_kb(struct sys_device *dev, struct sysdev_attribute *attr, |
458 | char *buf) | |
1775826c JF |
459 | { |
460 | return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages)); | |
461 | } | |
462 | ||
463 | static ssize_t store_target_kb(struct sys_device *dev, | |
4a0b2b4d | 464 | struct sysdev_attribute *attr, |
1775826c JF |
465 | const char *buf, |
466 | size_t count) | |
467 | { | |
167e6cf6 | 468 | char *endchar; |
1775826c JF |
469 | unsigned long long target_bytes; |
470 | ||
471 | if (!capable(CAP_SYS_ADMIN)) | |
472 | return -EPERM; | |
473 | ||
618b2c8d | 474 | target_bytes = simple_strtoull(buf, &endchar, 0) * 1024; |
1775826c | 475 | |
1775826c JF |
476 | balloon_set_new_target(target_bytes >> PAGE_SHIFT); |
477 | ||
478 | return count; | |
479 | } | |
480 | ||
481 | static SYSDEV_ATTR(target_kb, S_IRUGO | S_IWUSR, | |
482 | show_target_kb, store_target_kb); | |
483 | ||
618b2c8d JF |
484 | |
485 | static ssize_t show_target(struct sys_device *dev, struct sysdev_attribute *attr, | |
486 | char *buf) | |
487 | { | |
488 | return sprintf(buf, "%llu\n", | |
0692698c JB |
489 | (unsigned long long)balloon_stats.target_pages |
490 | << PAGE_SHIFT); | |
618b2c8d JF |
491 | } |
492 | ||
493 | static ssize_t store_target(struct sys_device *dev, | |
494 | struct sysdev_attribute *attr, | |
495 | const char *buf, | |
496 | size_t count) | |
497 | { | |
498 | char *endchar; | |
499 | unsigned long long target_bytes; | |
500 | ||
501 | if (!capable(CAP_SYS_ADMIN)) | |
502 | return -EPERM; | |
503 | ||
504 | target_bytes = memparse(buf, &endchar); | |
505 | ||
506 | balloon_set_new_target(target_bytes >> PAGE_SHIFT); | |
507 | ||
508 | return count; | |
509 | } | |
510 | ||
511 | static SYSDEV_ATTR(target, S_IRUGO | S_IWUSR, | |
512 | show_target, store_target); | |
513 | ||
514 | ||
1775826c JF |
515 | static struct sysdev_attribute *balloon_attrs[] = { |
516 | &attr_target_kb, | |
618b2c8d | 517 | &attr_target, |
1775826c JF |
518 | }; |
519 | ||
520 | static struct attribute *balloon_info_attrs[] = { | |
521 | &attr_current_kb.attr, | |
522 | &attr_low_kb.attr, | |
523 | &attr_high_kb.attr, | |
1775826c JF |
524 | &attr_driver_kb.attr, |
525 | NULL | |
526 | }; | |
527 | ||
528 | static struct attribute_group balloon_info_group = { | |
529 | .name = "info", | |
530 | .attrs = balloon_info_attrs, | |
531 | }; | |
532 | ||
533 | static struct sysdev_class balloon_sysdev_class = { | |
534 | .name = BALLOON_CLASS_NAME, | |
535 | }; | |
536 | ||
537 | static int register_balloon(struct sys_device *sysdev) | |
538 | { | |
539 | int i, error; | |
540 | ||
541 | error = sysdev_class_register(&balloon_sysdev_class); | |
542 | if (error) | |
543 | return error; | |
544 | ||
545 | sysdev->id = 0; | |
546 | sysdev->cls = &balloon_sysdev_class; | |
547 | ||
548 | error = sysdev_register(sysdev); | |
549 | if (error) { | |
550 | sysdev_class_unregister(&balloon_sysdev_class); | |
551 | return error; | |
552 | } | |
553 | ||
554 | for (i = 0; i < ARRAY_SIZE(balloon_attrs); i++) { | |
555 | error = sysdev_create_file(sysdev, balloon_attrs[i]); | |
556 | if (error) | |
557 | goto fail; | |
558 | } | |
559 | ||
560 | error = sysfs_create_group(&sysdev->kobj, &balloon_info_group); | |
561 | if (error) | |
562 | goto fail; | |
563 | ||
564 | return 0; | |
565 | ||
566 | fail: | |
567 | while (--i >= 0) | |
568 | sysdev_remove_file(sysdev, balloon_attrs[i]); | |
569 | sysdev_unregister(sysdev); | |
570 | sysdev_class_unregister(&balloon_sysdev_class); | |
571 | return error; | |
572 | } | |
573 | ||
1775826c | 574 | MODULE_LICENSE("GPL"); |