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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 | ||
88 | /* | |
89 | * Protects atomic reservation decrease/increase against concurrent increases. | |
90 | * Also protects non-atomic updates of current_pages and driver_pages, and | |
91 | * balloon lists. | |
92 | */ | |
93 | static DEFINE_SPINLOCK(balloon_lock); | |
94 | ||
95 | static struct balloon_stats balloon_stats; | |
96 | ||
97 | /* We increase/decrease in batches which fit in a page */ | |
98 | static unsigned long frame_list[PAGE_SIZE / sizeof(unsigned long)]; | |
99 | ||
1775826c | 100 | #ifdef CONFIG_HIGHMEM |
1775826c JF |
101 | #define inc_totalhigh_pages() (totalhigh_pages++) |
102 | #define dec_totalhigh_pages() (totalhigh_pages--) | |
103 | #else | |
104 | #define inc_totalhigh_pages() do {} while(0) | |
105 | #define dec_totalhigh_pages() do {} while(0) | |
106 | #endif | |
107 | ||
108 | /* List of ballooned pages, threaded through the mem_map array. */ | |
109 | static LIST_HEAD(ballooned_pages); | |
110 | ||
111 | /* Main work function, always executed in process context. */ | |
112 | static void balloon_process(struct work_struct *work); | |
113 | static DECLARE_WORK(balloon_worker, balloon_process); | |
114 | static struct timer_list balloon_timer; | |
115 | ||
116 | /* When ballooning out (allocating memory to return to Xen) we don't really | |
117 | want the kernel to try too hard since that can trigger the oom killer. */ | |
118 | #define GFP_BALLOON \ | |
119 | (GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC) | |
120 | ||
121 | static void scrub_page(struct page *page) | |
122 | { | |
123 | #ifdef CONFIG_XEN_SCRUB_PAGES | |
26a3e991 | 124 | clear_highpage(page); |
1775826c JF |
125 | #endif |
126 | } | |
127 | ||
128 | /* balloon_append: add the given page to the balloon. */ | |
129 | static void balloon_append(struct page *page) | |
130 | { | |
131 | /* Lowmem is re-populated first, so highmem pages go at list tail. */ | |
132 | if (PageHighMem(page)) { | |
133 | list_add_tail(&page->lru, &ballooned_pages); | |
134 | balloon_stats.balloon_high++; | |
135 | dec_totalhigh_pages(); | |
136 | } else { | |
137 | list_add(&page->lru, &ballooned_pages); | |
138 | balloon_stats.balloon_low++; | |
139 | } | |
3d65c948 GG |
140 | |
141 | totalram_pages--; | |
1775826c JF |
142 | } |
143 | ||
144 | /* balloon_retrieve: rescue a page from the balloon, if it is not empty. */ | |
145 | static struct page *balloon_retrieve(void) | |
146 | { | |
147 | struct page *page; | |
148 | ||
149 | if (list_empty(&ballooned_pages)) | |
150 | return NULL; | |
151 | ||
152 | page = list_entry(ballooned_pages.next, struct page, lru); | |
153 | list_del(&page->lru); | |
154 | ||
155 | if (PageHighMem(page)) { | |
156 | balloon_stats.balloon_high--; | |
157 | inc_totalhigh_pages(); | |
158 | } | |
159 | else | |
160 | balloon_stats.balloon_low--; | |
161 | ||
3d65c948 GG |
162 | totalram_pages++; |
163 | ||
1775826c JF |
164 | return page; |
165 | } | |
166 | ||
167 | static struct page *balloon_first_page(void) | |
168 | { | |
169 | if (list_empty(&ballooned_pages)) | |
170 | return NULL; | |
171 | return list_entry(ballooned_pages.next, struct page, lru); | |
172 | } | |
173 | ||
174 | static struct page *balloon_next_page(struct page *page) | |
175 | { | |
176 | struct list_head *next = page->lru.next; | |
177 | if (next == &ballooned_pages) | |
178 | return NULL; | |
179 | return list_entry(next, struct page, lru); | |
180 | } | |
181 | ||
182 | static void balloon_alarm(unsigned long unused) | |
183 | { | |
184 | schedule_work(&balloon_worker); | |
185 | } | |
186 | ||
187 | static unsigned long current_target(void) | |
188 | { | |
bc2c0303 | 189 | unsigned long target = balloon_stats.target_pages; |
1775826c JF |
190 | |
191 | target = min(target, | |
192 | balloon_stats.current_pages + | |
193 | balloon_stats.balloon_low + | |
194 | balloon_stats.balloon_high); | |
195 | ||
196 | return target; | |
197 | } | |
198 | ||
199 | static int increase_reservation(unsigned long nr_pages) | |
200 | { | |
201 | unsigned long pfn, i, flags; | |
202 | struct page *page; | |
203 | long rc; | |
204 | struct xen_memory_reservation reservation = { | |
205 | .address_bits = 0, | |
206 | .extent_order = 0, | |
207 | .domid = DOMID_SELF | |
208 | }; | |
209 | ||
210 | if (nr_pages > ARRAY_SIZE(frame_list)) | |
211 | nr_pages = ARRAY_SIZE(frame_list); | |
212 | ||
213 | spin_lock_irqsave(&balloon_lock, flags); | |
214 | ||
215 | page = balloon_first_page(); | |
216 | for (i = 0; i < nr_pages; i++) { | |
217 | BUG_ON(page == NULL); | |
a419aef8 | 218 | frame_list[i] = page_to_pfn(page); |
1775826c JF |
219 | page = balloon_next_page(page); |
220 | } | |
221 | ||
a90971eb | 222 | set_xen_guest_handle(reservation.extent_start, frame_list); |
fde28e8f JF |
223 | reservation.nr_extents = nr_pages; |
224 | rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation); | |
bc2c0303 | 225 | if (rc < 0) |
1775826c | 226 | goto out; |
1775826c | 227 | |
bc2c0303 | 228 | for (i = 0; i < rc; i++) { |
1775826c JF |
229 | page = balloon_retrieve(); |
230 | BUG_ON(page == NULL); | |
231 | ||
232 | pfn = page_to_pfn(page); | |
233 | BUG_ON(!xen_feature(XENFEAT_auto_translated_physmap) && | |
234 | phys_to_machine_mapping_valid(pfn)); | |
235 | ||
236 | set_phys_to_machine(pfn, frame_list[i]); | |
237 | ||
238 | /* Link back into the page tables if not highmem. */ | |
239 | if (pfn < max_low_pfn) { | |
240 | int ret; | |
241 | ret = HYPERVISOR_update_va_mapping( | |
242 | (unsigned long)__va(pfn << PAGE_SHIFT), | |
243 | mfn_pte(frame_list[i], PAGE_KERNEL), | |
244 | 0); | |
245 | BUG_ON(ret); | |
246 | } | |
247 | ||
248 | /* Relinquish the page back to the allocator. */ | |
249 | ClearPageReserved(page); | |
250 | init_page_count(page); | |
251 | __free_page(page); | |
252 | } | |
253 | ||
bc2c0303 | 254 | balloon_stats.current_pages += rc; |
1775826c JF |
255 | |
256 | out: | |
257 | spin_unlock_irqrestore(&balloon_lock, flags); | |
258 | ||
bc2c0303 | 259 | return rc < 0 ? rc : rc != nr_pages; |
1775826c JF |
260 | } |
261 | ||
262 | static int decrease_reservation(unsigned long nr_pages) | |
263 | { | |
264 | unsigned long pfn, i, flags; | |
265 | struct page *page; | |
266 | int need_sleep = 0; | |
267 | int ret; | |
268 | struct xen_memory_reservation reservation = { | |
269 | .address_bits = 0, | |
270 | .extent_order = 0, | |
271 | .domid = DOMID_SELF | |
272 | }; | |
273 | ||
274 | if (nr_pages > ARRAY_SIZE(frame_list)) | |
275 | nr_pages = ARRAY_SIZE(frame_list); | |
276 | ||
277 | for (i = 0; i < nr_pages; i++) { | |
278 | if ((page = alloc_page(GFP_BALLOON)) == NULL) { | |
279 | nr_pages = i; | |
280 | need_sleep = 1; | |
281 | break; | |
282 | } | |
283 | ||
284 | pfn = page_to_pfn(page); | |
285 | frame_list[i] = pfn_to_mfn(pfn); | |
286 | ||
287 | scrub_page(page); | |
1058a75f | 288 | |
ff4ce8c3 IC |
289 | if (!PageHighMem(page)) { |
290 | ret = HYPERVISOR_update_va_mapping( | |
291 | (unsigned long)__va(pfn << PAGE_SHIFT), | |
292 | __pte_ma(0), 0); | |
293 | BUG_ON(ret); | |
294 | } | |
295 | ||
1775826c JF |
296 | } |
297 | ||
298 | /* Ensure that ballooned highmem pages don't have kmaps. */ | |
299 | kmap_flush_unused(); | |
300 | flush_tlb_all(); | |
301 | ||
302 | spin_lock_irqsave(&balloon_lock, flags); | |
303 | ||
304 | /* No more mappings: invalidate P2M and add to balloon. */ | |
305 | for (i = 0; i < nr_pages; i++) { | |
306 | pfn = mfn_to_pfn(frame_list[i]); | |
307 | set_phys_to_machine(pfn, INVALID_P2M_ENTRY); | |
308 | balloon_append(pfn_to_page(pfn)); | |
309 | } | |
310 | ||
a90971eb | 311 | set_xen_guest_handle(reservation.extent_start, frame_list); |
1775826c JF |
312 | reservation.nr_extents = nr_pages; |
313 | ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation); | |
314 | BUG_ON(ret != nr_pages); | |
315 | ||
316 | balloon_stats.current_pages -= nr_pages; | |
1775826c JF |
317 | |
318 | spin_unlock_irqrestore(&balloon_lock, flags); | |
319 | ||
320 | return need_sleep; | |
321 | } | |
322 | ||
323 | /* | |
324 | * We avoid multiple worker processes conflicting via the balloon mutex. | |
325 | * We may of course race updates of the target counts (which are protected | |
326 | * by the balloon lock), or with changes to the Xen hard limit, but we will | |
327 | * recover from these in time. | |
328 | */ | |
329 | static void balloon_process(struct work_struct *work) | |
330 | { | |
331 | int need_sleep = 0; | |
332 | long credit; | |
333 | ||
334 | mutex_lock(&balloon_mutex); | |
335 | ||
336 | do { | |
337 | credit = current_target() - balloon_stats.current_pages; | |
338 | if (credit > 0) | |
339 | need_sleep = (increase_reservation(credit) != 0); | |
340 | if (credit < 0) | |
341 | need_sleep = (decrease_reservation(-credit) != 0); | |
342 | ||
343 | #ifndef CONFIG_PREEMPT | |
344 | if (need_resched()) | |
345 | schedule(); | |
346 | #endif | |
347 | } while ((credit != 0) && !need_sleep); | |
348 | ||
349 | /* Schedule more work if there is some still to be done. */ | |
350 | if (current_target() != balloon_stats.current_pages) | |
351 | mod_timer(&balloon_timer, jiffies + HZ); | |
352 | ||
353 | mutex_unlock(&balloon_mutex); | |
354 | } | |
355 | ||
356 | /* Resets the Xen limit, sets new target, and kicks off processing. */ | |
955d6f17 | 357 | static void balloon_set_new_target(unsigned long target) |
1775826c JF |
358 | { |
359 | /* No need for lock. Not read-modify-write updates. */ | |
1775826c JF |
360 | balloon_stats.target_pages = target; |
361 | schedule_work(&balloon_worker); | |
362 | } | |
363 | ||
364 | static struct xenbus_watch target_watch = | |
365 | { | |
366 | .node = "memory/target" | |
367 | }; | |
368 | ||
369 | /* React to a change in the target key */ | |
370 | static void watch_target(struct xenbus_watch *watch, | |
371 | const char **vec, unsigned int len) | |
372 | { | |
373 | unsigned long long new_target; | |
374 | int err; | |
375 | ||
376 | err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target); | |
377 | if (err != 1) { | |
378 | /* This is ok (for domain0 at least) - so just return */ | |
379 | return; | |
380 | } | |
381 | ||
382 | /* The given memory/target value is in KiB, so it needs converting to | |
383 | * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10. | |
384 | */ | |
385 | balloon_set_new_target(new_target >> (PAGE_SHIFT - 10)); | |
386 | } | |
387 | ||
388 | static int balloon_init_watcher(struct notifier_block *notifier, | |
389 | unsigned long event, | |
390 | void *data) | |
391 | { | |
392 | int err; | |
393 | ||
394 | err = register_xenbus_watch(&target_watch); | |
395 | if (err) | |
396 | printk(KERN_ERR "Failed to set balloon watcher\n"); | |
397 | ||
398 | return NOTIFY_DONE; | |
399 | } | |
400 | ||
401 | static struct notifier_block xenstore_notifier; | |
402 | ||
403 | static int __init balloon_init(void) | |
404 | { | |
405 | unsigned long pfn; | |
406 | struct page *page; | |
407 | ||
6e833587 | 408 | if (!xen_pv_domain()) |
1775826c JF |
409 | return -ENODEV; |
410 | ||
411 | pr_info("xen_balloon: Initialising balloon driver.\n"); | |
412 | ||
413 | balloon_stats.current_pages = min(xen_start_info->nr_pages, max_pfn); | |
1775826c JF |
414 | balloon_stats.target_pages = balloon_stats.current_pages; |
415 | balloon_stats.balloon_low = 0; | |
416 | balloon_stats.balloon_high = 0; | |
417 | balloon_stats.driver_pages = 0UL; | |
1775826c JF |
418 | |
419 | init_timer(&balloon_timer); | |
420 | balloon_timer.data = 0; | |
421 | balloon_timer.function = balloon_alarm; | |
422 | ||
423 | register_balloon(&balloon_sysdev); | |
424 | ||
425 | /* Initialise the balloon with excess memory space. */ | |
426 | for (pfn = xen_start_info->nr_pages; pfn < max_pfn; pfn++) { | |
427 | page = pfn_to_page(pfn); | |
428 | if (!PageReserved(page)) | |
429 | balloon_append(page); | |
430 | } | |
431 | ||
432 | target_watch.callback = watch_target; | |
433 | xenstore_notifier.notifier_call = balloon_init_watcher; | |
434 | ||
435 | register_xenstore_notifier(&xenstore_notifier); | |
436 | ||
437 | return 0; | |
438 | } | |
439 | ||
440 | subsys_initcall(balloon_init); | |
441 | ||
442 | static void balloon_exit(void) | |
443 | { | |
444 | /* XXX - release balloon here */ | |
445 | return; | |
446 | } | |
447 | ||
448 | module_exit(balloon_exit); | |
449 | ||
167e6cf6 JF |
450 | #define BALLOON_SHOW(name, format, args...) \ |
451 | static ssize_t show_##name(struct sys_device *dev, \ | |
452 | struct sysdev_attribute *attr, \ | |
453 | char *buf) \ | |
454 | { \ | |
455 | return sprintf(buf, format, ##args); \ | |
456 | } \ | |
1775826c JF |
457 | static SYSDEV_ATTR(name, S_IRUGO, show_##name, NULL) |
458 | ||
459 | BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages)); | |
460 | BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low)); | |
461 | BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high)); | |
1775826c JF |
462 | BALLOON_SHOW(driver_kb, "%lu\n", PAGES2KB(balloon_stats.driver_pages)); |
463 | ||
167e6cf6 JF |
464 | static ssize_t show_target_kb(struct sys_device *dev, struct sysdev_attribute *attr, |
465 | char *buf) | |
1775826c JF |
466 | { |
467 | return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages)); | |
468 | } | |
469 | ||
470 | static ssize_t store_target_kb(struct sys_device *dev, | |
4a0b2b4d | 471 | struct sysdev_attribute *attr, |
1775826c JF |
472 | const char *buf, |
473 | size_t count) | |
474 | { | |
167e6cf6 | 475 | char *endchar; |
1775826c JF |
476 | unsigned long long target_bytes; |
477 | ||
478 | if (!capable(CAP_SYS_ADMIN)) | |
479 | return -EPERM; | |
480 | ||
618b2c8d | 481 | target_bytes = simple_strtoull(buf, &endchar, 0) * 1024; |
1775826c | 482 | |
1775826c JF |
483 | balloon_set_new_target(target_bytes >> PAGE_SHIFT); |
484 | ||
485 | return count; | |
486 | } | |
487 | ||
488 | static SYSDEV_ATTR(target_kb, S_IRUGO | S_IWUSR, | |
489 | show_target_kb, store_target_kb); | |
490 | ||
618b2c8d JF |
491 | |
492 | static ssize_t show_target(struct sys_device *dev, struct sysdev_attribute *attr, | |
493 | char *buf) | |
494 | { | |
495 | return sprintf(buf, "%llu\n", | |
0692698c JB |
496 | (unsigned long long)balloon_stats.target_pages |
497 | << PAGE_SHIFT); | |
618b2c8d JF |
498 | } |
499 | ||
500 | static ssize_t store_target(struct sys_device *dev, | |
501 | struct sysdev_attribute *attr, | |
502 | const char *buf, | |
503 | size_t count) | |
504 | { | |
505 | char *endchar; | |
506 | unsigned long long target_bytes; | |
507 | ||
508 | if (!capable(CAP_SYS_ADMIN)) | |
509 | return -EPERM; | |
510 | ||
511 | target_bytes = memparse(buf, &endchar); | |
512 | ||
513 | balloon_set_new_target(target_bytes >> PAGE_SHIFT); | |
514 | ||
515 | return count; | |
516 | } | |
517 | ||
518 | static SYSDEV_ATTR(target, S_IRUGO | S_IWUSR, | |
519 | show_target, store_target); | |
520 | ||
521 | ||
1775826c JF |
522 | static struct sysdev_attribute *balloon_attrs[] = { |
523 | &attr_target_kb, | |
618b2c8d | 524 | &attr_target, |
1775826c JF |
525 | }; |
526 | ||
527 | static struct attribute *balloon_info_attrs[] = { | |
528 | &attr_current_kb.attr, | |
529 | &attr_low_kb.attr, | |
530 | &attr_high_kb.attr, | |
1775826c JF |
531 | &attr_driver_kb.attr, |
532 | NULL | |
533 | }; | |
534 | ||
535 | static struct attribute_group balloon_info_group = { | |
536 | .name = "info", | |
537 | .attrs = balloon_info_attrs, | |
538 | }; | |
539 | ||
540 | static struct sysdev_class balloon_sysdev_class = { | |
541 | .name = BALLOON_CLASS_NAME, | |
542 | }; | |
543 | ||
544 | static int register_balloon(struct sys_device *sysdev) | |
545 | { | |
546 | int i, error; | |
547 | ||
548 | error = sysdev_class_register(&balloon_sysdev_class); | |
549 | if (error) | |
550 | return error; | |
551 | ||
552 | sysdev->id = 0; | |
553 | sysdev->cls = &balloon_sysdev_class; | |
554 | ||
555 | error = sysdev_register(sysdev); | |
556 | if (error) { | |
557 | sysdev_class_unregister(&balloon_sysdev_class); | |
558 | return error; | |
559 | } | |
560 | ||
561 | for (i = 0; i < ARRAY_SIZE(balloon_attrs); i++) { | |
562 | error = sysdev_create_file(sysdev, balloon_attrs[i]); | |
563 | if (error) | |
564 | goto fail; | |
565 | } | |
566 | ||
567 | error = sysfs_create_group(&sysdev->kobj, &balloon_info_group); | |
568 | if (error) | |
569 | goto fail; | |
570 | ||
571 | return 0; | |
572 | ||
573 | fail: | |
574 | while (--i >= 0) | |
575 | sysdev_remove_file(sysdev, balloon_attrs[i]); | |
576 | sysdev_unregister(sysdev); | |
577 | sysdev_class_unregister(&balloon_sysdev_class); | |
578 | return error; | |
579 | } | |
580 | ||
1775826c | 581 | MODULE_LICENSE("GPL"); |