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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> | |
66946f67 | 53 | #include <asm/e820.h> |
1775826c | 54 | |
ecbf29cd JF |
55 | #include <asm/xen/hypervisor.h> |
56 | #include <asm/xen/hypercall.h> | |
1ccbf534 JF |
57 | |
58 | #include <xen/xen.h> | |
ecbf29cd | 59 | #include <xen/interface/xen.h> |
1775826c | 60 | #include <xen/interface/memory.h> |
1775826c JF |
61 | #include <xen/xenbus.h> |
62 | #include <xen/features.h> | |
63 | #include <xen/page.h> | |
64 | ||
65 | #define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10)) | |
66 | ||
167e6cf6 | 67 | #define BALLOON_CLASS_NAME "xen_memory" |
1775826c JF |
68 | |
69 | struct balloon_stats { | |
70 | /* We aim for 'current allocation' == 'target allocation'. */ | |
71 | unsigned long current_pages; | |
72 | unsigned long target_pages; | |
1775826c JF |
73 | /* |
74 | * Drivers may alter the memory reservation independently, but they | |
75 | * must inform the balloon driver so we avoid hitting the hard limit. | |
76 | */ | |
77 | unsigned long driver_pages; | |
78 | /* Number of pages in high- and low-memory balloons. */ | |
79 | unsigned long balloon_low; | |
80 | unsigned long balloon_high; | |
81 | }; | |
82 | ||
83 | static DEFINE_MUTEX(balloon_mutex); | |
84 | ||
85 | static struct sys_device balloon_sysdev; | |
86 | ||
87 | static int register_balloon(struct sys_device *sysdev); | |
88 | ||
1775826c JF |
89 | static struct balloon_stats balloon_stats; |
90 | ||
91 | /* We increase/decrease in batches which fit in a page */ | |
92 | static unsigned long frame_list[PAGE_SIZE / sizeof(unsigned long)]; | |
93 | ||
1775826c | 94 | #ifdef CONFIG_HIGHMEM |
1775826c JF |
95 | #define inc_totalhigh_pages() (totalhigh_pages++) |
96 | #define dec_totalhigh_pages() (totalhigh_pages--) | |
97 | #else | |
98 | #define inc_totalhigh_pages() do {} while(0) | |
99 | #define dec_totalhigh_pages() do {} while(0) | |
100 | #endif | |
101 | ||
102 | /* List of ballooned pages, threaded through the mem_map array. */ | |
103 | static LIST_HEAD(ballooned_pages); | |
104 | ||
105 | /* Main work function, always executed in process context. */ | |
106 | static void balloon_process(struct work_struct *work); | |
107 | static DECLARE_WORK(balloon_worker, balloon_process); | |
108 | static struct timer_list balloon_timer; | |
109 | ||
110 | /* When ballooning out (allocating memory to return to Xen) we don't really | |
111 | want the kernel to try too hard since that can trigger the oom killer. */ | |
112 | #define GFP_BALLOON \ | |
113 | (GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC) | |
114 | ||
115 | static void scrub_page(struct page *page) | |
116 | { | |
117 | #ifdef CONFIG_XEN_SCRUB_PAGES | |
26a3e991 | 118 | clear_highpage(page); |
1775826c JF |
119 | #endif |
120 | } | |
121 | ||
122 | /* balloon_append: add the given page to the balloon. */ | |
9be4d457 | 123 | static void __balloon_append(struct page *page) |
1775826c JF |
124 | { |
125 | /* Lowmem is re-populated first, so highmem pages go at list tail. */ | |
126 | if (PageHighMem(page)) { | |
127 | list_add_tail(&page->lru, &ballooned_pages); | |
128 | balloon_stats.balloon_high++; | |
129 | dec_totalhigh_pages(); | |
130 | } else { | |
131 | list_add(&page->lru, &ballooned_pages); | |
132 | balloon_stats.balloon_low++; | |
133 | } | |
9be4d457 | 134 | } |
3d65c948 | 135 | |
9be4d457 JF |
136 | static void balloon_append(struct page *page) |
137 | { | |
138 | __balloon_append(page); | |
3d65c948 | 139 | totalram_pages--; |
1775826c JF |
140 | } |
141 | ||
142 | /* balloon_retrieve: rescue a page from the balloon, if it is not empty. */ | |
143 | static struct page *balloon_retrieve(void) | |
144 | { | |
145 | struct page *page; | |
146 | ||
147 | if (list_empty(&ballooned_pages)) | |
148 | return NULL; | |
149 | ||
150 | page = list_entry(ballooned_pages.next, struct page, lru); | |
151 | list_del(&page->lru); | |
152 | ||
153 | if (PageHighMem(page)) { | |
154 | balloon_stats.balloon_high--; | |
155 | inc_totalhigh_pages(); | |
156 | } | |
157 | else | |
158 | balloon_stats.balloon_low--; | |
159 | ||
3d65c948 GG |
160 | totalram_pages++; |
161 | ||
1775826c JF |
162 | return page; |
163 | } | |
164 | ||
165 | static struct page *balloon_first_page(void) | |
166 | { | |
167 | if (list_empty(&ballooned_pages)) | |
168 | return NULL; | |
169 | return list_entry(ballooned_pages.next, struct page, lru); | |
170 | } | |
171 | ||
172 | static struct page *balloon_next_page(struct page *page) | |
173 | { | |
174 | struct list_head *next = page->lru.next; | |
175 | if (next == &ballooned_pages) | |
176 | return NULL; | |
177 | return list_entry(next, struct page, lru); | |
178 | } | |
179 | ||
180 | static void balloon_alarm(unsigned long unused) | |
181 | { | |
182 | schedule_work(&balloon_worker); | |
183 | } | |
184 | ||
185 | static unsigned long current_target(void) | |
186 | { | |
bc2c0303 | 187 | unsigned long target = balloon_stats.target_pages; |
1775826c JF |
188 | |
189 | target = min(target, | |
190 | balloon_stats.current_pages + | |
191 | balloon_stats.balloon_low + | |
192 | balloon_stats.balloon_high); | |
193 | ||
194 | return target; | |
195 | } | |
196 | ||
197 | static int increase_reservation(unsigned long nr_pages) | |
198 | { | |
2f70e0ac | 199 | unsigned long pfn, i; |
1775826c JF |
200 | struct page *page; |
201 | long rc; | |
202 | struct xen_memory_reservation reservation = { | |
203 | .address_bits = 0, | |
204 | .extent_order = 0, | |
205 | .domid = DOMID_SELF | |
206 | }; | |
207 | ||
208 | if (nr_pages > ARRAY_SIZE(frame_list)) | |
209 | nr_pages = ARRAY_SIZE(frame_list); | |
210 | ||
1775826c JF |
211 | page = balloon_first_page(); |
212 | for (i = 0; i < nr_pages; i++) { | |
213 | BUG_ON(page == NULL); | |
a419aef8 | 214 | frame_list[i] = page_to_pfn(page); |
1775826c JF |
215 | page = balloon_next_page(page); |
216 | } | |
217 | ||
a90971eb | 218 | set_xen_guest_handle(reservation.extent_start, frame_list); |
fde28e8f JF |
219 | reservation.nr_extents = nr_pages; |
220 | rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation); | |
bc2c0303 | 221 | if (rc < 0) |
1775826c | 222 | goto out; |
1775826c | 223 | |
bc2c0303 | 224 | for (i = 0; i < rc; i++) { |
1775826c JF |
225 | page = balloon_retrieve(); |
226 | BUG_ON(page == NULL); | |
227 | ||
228 | pfn = page_to_pfn(page); | |
229 | BUG_ON(!xen_feature(XENFEAT_auto_translated_physmap) && | |
230 | phys_to_machine_mapping_valid(pfn)); | |
231 | ||
232 | set_phys_to_machine(pfn, frame_list[i]); | |
233 | ||
234 | /* Link back into the page tables if not highmem. */ | |
235 | if (pfn < max_low_pfn) { | |
236 | int ret; | |
237 | ret = HYPERVISOR_update_va_mapping( | |
238 | (unsigned long)__va(pfn << PAGE_SHIFT), | |
239 | mfn_pte(frame_list[i], PAGE_KERNEL), | |
240 | 0); | |
241 | BUG_ON(ret); | |
242 | } | |
243 | ||
244 | /* Relinquish the page back to the allocator. */ | |
245 | ClearPageReserved(page); | |
246 | init_page_count(page); | |
247 | __free_page(page); | |
248 | } | |
249 | ||
bc2c0303 | 250 | balloon_stats.current_pages += rc; |
1775826c JF |
251 | |
252 | out: | |
bc2c0303 | 253 | return rc < 0 ? rc : rc != nr_pages; |
1775826c JF |
254 | } |
255 | ||
256 | static int decrease_reservation(unsigned long nr_pages) | |
257 | { | |
2f70e0ac | 258 | unsigned long pfn, i; |
1775826c JF |
259 | struct page *page; |
260 | int need_sleep = 0; | |
261 | int ret; | |
262 | struct xen_memory_reservation reservation = { | |
263 | .address_bits = 0, | |
264 | .extent_order = 0, | |
265 | .domid = DOMID_SELF | |
266 | }; | |
267 | ||
268 | if (nr_pages > ARRAY_SIZE(frame_list)) | |
269 | nr_pages = ARRAY_SIZE(frame_list); | |
270 | ||
271 | for (i = 0; i < nr_pages; i++) { | |
272 | if ((page = alloc_page(GFP_BALLOON)) == NULL) { | |
273 | nr_pages = i; | |
274 | need_sleep = 1; | |
275 | break; | |
276 | } | |
277 | ||
278 | pfn = page_to_pfn(page); | |
279 | frame_list[i] = pfn_to_mfn(pfn); | |
280 | ||
281 | scrub_page(page); | |
1058a75f | 282 | |
ff4ce8c3 IC |
283 | if (!PageHighMem(page)) { |
284 | ret = HYPERVISOR_update_va_mapping( | |
285 | (unsigned long)__va(pfn << PAGE_SHIFT), | |
286 | __pte_ma(0), 0); | |
287 | BUG_ON(ret); | |
288 | } | |
289 | ||
1775826c JF |
290 | } |
291 | ||
292 | /* Ensure that ballooned highmem pages don't have kmaps. */ | |
293 | kmap_flush_unused(); | |
294 | flush_tlb_all(); | |
295 | ||
1775826c JF |
296 | /* No more mappings: invalidate P2M and add to balloon. */ |
297 | for (i = 0; i < nr_pages; i++) { | |
298 | pfn = mfn_to_pfn(frame_list[i]); | |
299 | set_phys_to_machine(pfn, INVALID_P2M_ENTRY); | |
300 | balloon_append(pfn_to_page(pfn)); | |
301 | } | |
302 | ||
a90971eb | 303 | set_xen_guest_handle(reservation.extent_start, frame_list); |
1775826c JF |
304 | reservation.nr_extents = nr_pages; |
305 | ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation); | |
306 | BUG_ON(ret != nr_pages); | |
307 | ||
308 | balloon_stats.current_pages -= nr_pages; | |
1775826c | 309 | |
1775826c JF |
310 | return need_sleep; |
311 | } | |
312 | ||
313 | /* | |
314 | * We avoid multiple worker processes conflicting via the balloon mutex. | |
315 | * We may of course race updates of the target counts (which are protected | |
316 | * by the balloon lock), or with changes to the Xen hard limit, but we will | |
317 | * recover from these in time. | |
318 | */ | |
319 | static void balloon_process(struct work_struct *work) | |
320 | { | |
321 | int need_sleep = 0; | |
322 | long credit; | |
323 | ||
324 | mutex_lock(&balloon_mutex); | |
325 | ||
326 | do { | |
327 | credit = current_target() - balloon_stats.current_pages; | |
328 | if (credit > 0) | |
329 | need_sleep = (increase_reservation(credit) != 0); | |
330 | if (credit < 0) | |
331 | need_sleep = (decrease_reservation(-credit) != 0); | |
332 | ||
333 | #ifndef CONFIG_PREEMPT | |
334 | if (need_resched()) | |
335 | schedule(); | |
336 | #endif | |
337 | } while ((credit != 0) && !need_sleep); | |
338 | ||
339 | /* Schedule more work if there is some still to be done. */ | |
340 | if (current_target() != balloon_stats.current_pages) | |
341 | mod_timer(&balloon_timer, jiffies + HZ); | |
342 | ||
343 | mutex_unlock(&balloon_mutex); | |
344 | } | |
345 | ||
346 | /* Resets the Xen limit, sets new target, and kicks off processing. */ | |
955d6f17 | 347 | static void balloon_set_new_target(unsigned long target) |
1775826c JF |
348 | { |
349 | /* No need for lock. Not read-modify-write updates. */ | |
1775826c JF |
350 | balloon_stats.target_pages = target; |
351 | schedule_work(&balloon_worker); | |
352 | } | |
353 | ||
354 | static struct xenbus_watch target_watch = | |
355 | { | |
356 | .node = "memory/target" | |
357 | }; | |
358 | ||
359 | /* React to a change in the target key */ | |
360 | static void watch_target(struct xenbus_watch *watch, | |
361 | const char **vec, unsigned int len) | |
362 | { | |
363 | unsigned long long new_target; | |
364 | int err; | |
365 | ||
366 | err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target); | |
367 | if (err != 1) { | |
368 | /* This is ok (for domain0 at least) - so just return */ | |
369 | return; | |
370 | } | |
371 | ||
372 | /* The given memory/target value is in KiB, so it needs converting to | |
373 | * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10. | |
374 | */ | |
375 | balloon_set_new_target(new_target >> (PAGE_SHIFT - 10)); | |
376 | } | |
377 | ||
378 | static int balloon_init_watcher(struct notifier_block *notifier, | |
379 | unsigned long event, | |
380 | void *data) | |
381 | { | |
382 | int err; | |
383 | ||
384 | err = register_xenbus_watch(&target_watch); | |
385 | if (err) | |
386 | printk(KERN_ERR "Failed to set balloon watcher\n"); | |
387 | ||
388 | return NOTIFY_DONE; | |
389 | } | |
390 | ||
391 | static struct notifier_block xenstore_notifier; | |
392 | ||
393 | static int __init balloon_init(void) | |
394 | { | |
66946f67 | 395 | unsigned long pfn, extra_pfn_end; |
1775826c JF |
396 | struct page *page; |
397 | ||
6e833587 | 398 | if (!xen_pv_domain()) |
1775826c JF |
399 | return -ENODEV; |
400 | ||
401 | pr_info("xen_balloon: Initialising balloon driver.\n"); | |
402 | ||
403 | balloon_stats.current_pages = min(xen_start_info->nr_pages, max_pfn); | |
1775826c JF |
404 | balloon_stats.target_pages = balloon_stats.current_pages; |
405 | balloon_stats.balloon_low = 0; | |
406 | balloon_stats.balloon_high = 0; | |
407 | balloon_stats.driver_pages = 0UL; | |
1775826c JF |
408 | |
409 | init_timer(&balloon_timer); | |
410 | balloon_timer.data = 0; | |
411 | balloon_timer.function = balloon_alarm; | |
412 | ||
413 | register_balloon(&balloon_sysdev); | |
414 | ||
415 | /* Initialise the balloon with excess memory space. */ | |
66946f67 JF |
416 | extra_pfn_end = min(e820_end_of_ram_pfn(), |
417 | (unsigned long)PFN_DOWN(xen_extra_mem_start + xen_extra_mem_size)); | |
9be4d457 | 418 | for (pfn = PFN_UP(xen_extra_mem_start); |
66946f67 | 419 | pfn < extra_pfn_end; |
9be4d457 | 420 | pfn++) { |
1775826c | 421 | page = pfn_to_page(pfn); |
9be4d457 JF |
422 | /* totalram_pages doesn't include the boot-time |
423 | balloon extension, so don't subtract from it. */ | |
424 | __balloon_append(page); | |
1775826c JF |
425 | } |
426 | ||
427 | target_watch.callback = watch_target; | |
428 | xenstore_notifier.notifier_call = balloon_init_watcher; | |
429 | ||
430 | register_xenstore_notifier(&xenstore_notifier); | |
431 | ||
432 | return 0; | |
433 | } | |
434 | ||
435 | subsys_initcall(balloon_init); | |
436 | ||
437 | static void balloon_exit(void) | |
438 | { | |
439 | /* XXX - release balloon here */ | |
440 | return; | |
441 | } | |
442 | ||
443 | module_exit(balloon_exit); | |
444 | ||
167e6cf6 JF |
445 | #define BALLOON_SHOW(name, format, args...) \ |
446 | static ssize_t show_##name(struct sys_device *dev, \ | |
447 | struct sysdev_attribute *attr, \ | |
448 | char *buf) \ | |
449 | { \ | |
450 | return sprintf(buf, format, ##args); \ | |
451 | } \ | |
1775826c JF |
452 | static SYSDEV_ATTR(name, S_IRUGO, show_##name, NULL) |
453 | ||
454 | BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages)); | |
455 | BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low)); | |
456 | BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high)); | |
1775826c JF |
457 | BALLOON_SHOW(driver_kb, "%lu\n", PAGES2KB(balloon_stats.driver_pages)); |
458 | ||
167e6cf6 JF |
459 | static ssize_t show_target_kb(struct sys_device *dev, struct sysdev_attribute *attr, |
460 | char *buf) | |
1775826c JF |
461 | { |
462 | return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages)); | |
463 | } | |
464 | ||
465 | static ssize_t store_target_kb(struct sys_device *dev, | |
4a0b2b4d | 466 | struct sysdev_attribute *attr, |
1775826c JF |
467 | const char *buf, |
468 | size_t count) | |
469 | { | |
167e6cf6 | 470 | char *endchar; |
1775826c JF |
471 | unsigned long long target_bytes; |
472 | ||
473 | if (!capable(CAP_SYS_ADMIN)) | |
474 | return -EPERM; | |
475 | ||
618b2c8d | 476 | target_bytes = simple_strtoull(buf, &endchar, 0) * 1024; |
1775826c | 477 | |
1775826c JF |
478 | balloon_set_new_target(target_bytes >> PAGE_SHIFT); |
479 | ||
480 | return count; | |
481 | } | |
482 | ||
483 | static SYSDEV_ATTR(target_kb, S_IRUGO | S_IWUSR, | |
484 | show_target_kb, store_target_kb); | |
485 | ||
618b2c8d JF |
486 | |
487 | static ssize_t show_target(struct sys_device *dev, struct sysdev_attribute *attr, | |
488 | char *buf) | |
489 | { | |
490 | return sprintf(buf, "%llu\n", | |
0692698c JB |
491 | (unsigned long long)balloon_stats.target_pages |
492 | << PAGE_SHIFT); | |
618b2c8d JF |
493 | } |
494 | ||
495 | static ssize_t store_target(struct sys_device *dev, | |
496 | struct sysdev_attribute *attr, | |
497 | const char *buf, | |
498 | size_t count) | |
499 | { | |
500 | char *endchar; | |
501 | unsigned long long target_bytes; | |
502 | ||
503 | if (!capable(CAP_SYS_ADMIN)) | |
504 | return -EPERM; | |
505 | ||
506 | target_bytes = memparse(buf, &endchar); | |
507 | ||
508 | balloon_set_new_target(target_bytes >> PAGE_SHIFT); | |
509 | ||
510 | return count; | |
511 | } | |
512 | ||
513 | static SYSDEV_ATTR(target, S_IRUGO | S_IWUSR, | |
514 | show_target, store_target); | |
515 | ||
516 | ||
1775826c JF |
517 | static struct sysdev_attribute *balloon_attrs[] = { |
518 | &attr_target_kb, | |
618b2c8d | 519 | &attr_target, |
1775826c JF |
520 | }; |
521 | ||
522 | static struct attribute *balloon_info_attrs[] = { | |
523 | &attr_current_kb.attr, | |
524 | &attr_low_kb.attr, | |
525 | &attr_high_kb.attr, | |
1775826c JF |
526 | &attr_driver_kb.attr, |
527 | NULL | |
528 | }; | |
529 | ||
530 | static struct attribute_group balloon_info_group = { | |
531 | .name = "info", | |
532 | .attrs = balloon_info_attrs, | |
533 | }; | |
534 | ||
535 | static struct sysdev_class balloon_sysdev_class = { | |
536 | .name = BALLOON_CLASS_NAME, | |
537 | }; | |
538 | ||
539 | static int register_balloon(struct sys_device *sysdev) | |
540 | { | |
541 | int i, error; | |
542 | ||
543 | error = sysdev_class_register(&balloon_sysdev_class); | |
544 | if (error) | |
545 | return error; | |
546 | ||
547 | sysdev->id = 0; | |
548 | sysdev->cls = &balloon_sysdev_class; | |
549 | ||
550 | error = sysdev_register(sysdev); | |
551 | if (error) { | |
552 | sysdev_class_unregister(&balloon_sysdev_class); | |
553 | return error; | |
554 | } | |
555 | ||
556 | for (i = 0; i < ARRAY_SIZE(balloon_attrs); i++) { | |
557 | error = sysdev_create_file(sysdev, balloon_attrs[i]); | |
558 | if (error) | |
559 | goto fail; | |
560 | } | |
561 | ||
562 | error = sysfs_create_group(&sysdev->kobj, &balloon_info_group); | |
563 | if (error) | |
564 | goto fail; | |
565 | ||
566 | return 0; | |
567 | ||
568 | fail: | |
569 | while (--i >= 0) | |
570 | sysdev_remove_file(sysdev, balloon_attrs[i]); | |
571 | sysdev_unregister(sysdev); | |
572 | sysdev_class_unregister(&balloon_sysdev_class); | |
573 | return error; | |
574 | } | |
575 | ||
1775826c | 576 | MODULE_LICENSE("GPL"); |