1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Persistent Storage - platform driver interface parts.
4 *
5 * Copyright (C) 2007-2008 Google, Inc.
6 * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
7 */
8
9 #define pr_fmt(fmt) "pstore: " fmt
10
11 #include <linux/atomic.h>
12 #include <linux/types.h>
13 #include <linux/errno.h>
14 #include <linux/init.h>
15 #include <linux/kmsg_dump.h>
16 #include <linux/console.h>
17 #include <linux/module.h>
18 #include <linux/pstore.h>
19 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
20 #include <linux/lzo.h>
21 #endif
22 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
23 #include <linux/lz4.h>
24 #endif
25 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
26 #include <linux/zstd.h>
27 #endif
28 #include <linux/crypto.h>
29 #include <linux/string.h>
30 #include <linux/timer.h>
31 #include <linux/slab.h>
32 #include <linux/uaccess.h>
33 #include <linux/jiffies.h>
34 #include <linux/workqueue.h>
35
36 #include "internal.h"
37
38 /*
39 * We defer making "oops" entries appear in pstore - see
40 * whether the system is actually still running well enough
41 * to let someone see the entry
42 */
43 static int pstore_update_ms = -1;
44 module_param_named(update_ms, pstore_update_ms, int, 0600);
45 MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
46 "(default is -1, which means runtime updates are disabled; "
47 "enabling this option may not be safe; it may lead to further "
48 "corruption on Oopses)");
49
50 /* Names should be in the same order as the enum pstore_type_id */
51 static const char * const pstore_type_names[] = {
52 "dmesg",
53 "mce",
54 "console",
55 "ftrace",
56 "rtas",
57 "powerpc-ofw",
58 "powerpc-common",
59 "pmsg",
60 "powerpc-opal",
61 #ifdef CONFIG_PSTORE_BOOT_LOG
62 "boot-log",
63 #endif
64 };
65
66 static int pstore_new_entry;
67
68 static void pstore_timefunc(struct timer_list *);
69 static DEFINE_TIMER(pstore_timer, pstore_timefunc);
70
71 static void pstore_dowork(struct work_struct *);
72 static DECLARE_WORK(pstore_work, pstore_dowork);
73
74 /*
75 * psinfo_lock protects "psinfo" during calls to
76 * pstore_register(), pstore_unregister(), and
77 * the filesystem mount/unmount routines.
78 */
79 static DEFINE_MUTEX(psinfo_lock);
80 struct pstore_info *psinfo;
81
82 static char *backend;
83 module_param(backend, charp, 0444);
84 MODULE_PARM_DESC(backend, "specific backend to use");
85
86 static char *compress =
87 #ifdef CONFIG_PSTORE_COMPRESS_DEFAULT
88 CONFIG_PSTORE_COMPRESS_DEFAULT;
89 #else
90 NULL;
91 #endif
92 module_param(compress, charp, 0444);
93 MODULE_PARM_DESC(compress, "compression to use");
94
95 /* Compression parameters */
96 static struct crypto_comp *tfm;
97
98 struct pstore_zbackend {
99 int (*zbufsize)(size_t size);
100 const char *name;
101 };
102
103 static char *big_oops_buf;
104 static size_t big_oops_buf_sz;
105
106 /* How much of the console log to snapshot */
107 unsigned long kmsg_bytes = PSTORE_DEFAULT_KMSG_BYTES;
108
pstore_set_kmsg_bytes(int bytes)109 void pstore_set_kmsg_bytes(int bytes)
110 {
111 kmsg_bytes = bytes;
112 }
113
114 /* Tag each group of saved records with a sequence number */
115 static int oopscount;
116
pstore_type_to_name(enum pstore_type_id type)117 const char *pstore_type_to_name(enum pstore_type_id type)
118 {
119 BUILD_BUG_ON(ARRAY_SIZE(pstore_type_names) != PSTORE_TYPE_MAX);
120
121 if (WARN_ON_ONCE(type >= PSTORE_TYPE_MAX))
122 return "unknown";
123
124 return pstore_type_names[type];
125 }
126 EXPORT_SYMBOL_GPL(pstore_type_to_name);
127
pstore_name_to_type(const char * name)128 enum pstore_type_id pstore_name_to_type(const char *name)
129 {
130 int i;
131
132 for (i = 0; i < PSTORE_TYPE_MAX; i++) {
133 if (!strcmp(pstore_type_names[i], name))
134 return i;
135 }
136
137 return PSTORE_TYPE_MAX;
138 }
139 EXPORT_SYMBOL_GPL(pstore_name_to_type);
140
pstore_timer_kick(void)141 static void pstore_timer_kick(void)
142 {
143 if (pstore_update_ms < 0)
144 return;
145
146 mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
147 }
148
149 /*
150 * Should pstore_dump() wait for a concurrent pstore_dump()? If
151 * not, the current pstore_dump() will report a failure to dump
152 * and return.
153 */
pstore_cannot_wait(enum kmsg_dump_reason reason)154 static bool pstore_cannot_wait(enum kmsg_dump_reason reason)
155 {
156 /* In NMI path, pstore shouldn't block regardless of reason. */
157 if (in_nmi())
158 return true;
159
160 switch (reason) {
161 /* In panic case, other cpus are stopped by smp_send_stop(). */
162 case KMSG_DUMP_PANIC:
163 /* Emergency restart shouldn't be blocked. */
164 case KMSG_DUMP_EMERG:
165 return true;
166 default:
167 return false;
168 }
169 }
170
171 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
zbufsize_deflate(size_t size)172 static int zbufsize_deflate(size_t size)
173 {
174 size_t cmpr;
175
176 switch (size) {
177 /* buffer range for efivars */
178 case 1000 ... 2000:
179 cmpr = 56;
180 break;
181 case 2001 ... 3000:
182 cmpr = 54;
183 break;
184 case 3001 ... 3999:
185 cmpr = 52;
186 break;
187 /* buffer range for nvram, erst */
188 case 4000 ... 10000:
189 cmpr = 45;
190 break;
191 default:
192 cmpr = 60;
193 break;
194 }
195
196 return (size * 100) / cmpr;
197 }
198 #endif
199
200 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
zbufsize_lzo(size_t size)201 static int zbufsize_lzo(size_t size)
202 {
203 return lzo1x_worst_compress(size);
204 }
205 #endif
206
207 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
zbufsize_lz4(size_t size)208 static int zbufsize_lz4(size_t size)
209 {
210 return LZ4_compressBound(size);
211 }
212 #endif
213
214 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
zbufsize_842(size_t size)215 static int zbufsize_842(size_t size)
216 {
217 return size;
218 }
219 #endif
220
221 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
zbufsize_zstd(size_t size)222 static int zbufsize_zstd(size_t size)
223 {
224 return ZSTD_compressBound(size);
225 }
226 #endif
227
228 static const struct pstore_zbackend *zbackend __ro_after_init;
229
230 static const struct pstore_zbackend zbackends[] = {
231 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
232 {
233 .zbufsize = zbufsize_deflate,
234 .name = "deflate",
235 },
236 #endif
237 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
238 {
239 .zbufsize = zbufsize_lzo,
240 .name = "lzo",
241 },
242 #endif
243 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS)
244 {
245 .zbufsize = zbufsize_lz4,
246 .name = "lz4",
247 },
248 #endif
249 #if IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
250 {
251 .zbufsize = zbufsize_lz4,
252 .name = "lz4hc",
253 },
254 #endif
255 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
256 {
257 .zbufsize = zbufsize_842,
258 .name = "842",
259 },
260 #endif
261 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
262 {
263 .zbufsize = zbufsize_zstd,
264 .name = "zstd",
265 },
266 #endif
267 { }
268 };
269
pstore_compress(const void * in,void * out,unsigned int inlen,unsigned int outlen)270 static int pstore_compress(const void *in, void *out,
271 unsigned int inlen, unsigned int outlen)
272 {
273 int ret;
274
275 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS))
276 return -EINVAL;
277
278 ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
279 if (ret) {
280 pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
281 return ret;
282 }
283
284 return outlen;
285 }
286
allocate_buf_for_compression(void)287 static void allocate_buf_for_compression(void)
288 {
289 struct crypto_comp *ctx;
290 int size;
291 char *buf;
292
293 /* Skip if not built-in or compression backend not selected yet. */
294 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
295 return;
296
297 /* Skip if no pstore backend yet or compression init already done. */
298 if (!psinfo || tfm)
299 return;
300
301 if (!crypto_has_comp(zbackend->name, 0, 0)) {
302 pr_err("Unknown compression: %s\n", zbackend->name);
303 return;
304 }
305
306 size = zbackend->zbufsize(psinfo->bufsize);
307 if (size <= 0) {
308 pr_err("Invalid compression size for %s: %d\n",
309 zbackend->name, size);
310 return;
311 }
312
313 buf = kmalloc(size, GFP_KERNEL);
314 if (!buf) {
315 pr_err("Failed %d byte compression buffer allocation for: %s\n",
316 size, zbackend->name);
317 return;
318 }
319
320 ctx = crypto_alloc_comp(zbackend->name, 0, 0);
321 if (IS_ERR_OR_NULL(ctx)) {
322 kfree(buf);
323 pr_err("crypto_alloc_comp('%s') failed: %ld\n", zbackend->name,
324 PTR_ERR(ctx));
325 return;
326 }
327
328 /* A non-NULL big_oops_buf indicates compression is available. */
329 tfm = ctx;
330 big_oops_buf_sz = size;
331 big_oops_buf = buf;
332
333 pr_info("Using crash dump compression: %s\n", zbackend->name);
334 }
335
free_buf_for_compression(void)336 static void free_buf_for_compression(void)
337 {
338 if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm) {
339 crypto_free_comp(tfm);
340 tfm = NULL;
341 }
342 kfree(big_oops_buf);
343 big_oops_buf = NULL;
344 big_oops_buf_sz = 0;
345 }
346
347 /*
348 * Called when compression fails, since the printk buffer
349 * would be fetched for compression calling it again when
350 * compression fails would have moved the iterator of
351 * printk buffer which results in fetching old contents.
352 * Copy the recent messages from big_oops_buf to psinfo->buf
353 */
copy_kmsg_to_buffer(int hsize,size_t len)354 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
355 {
356 size_t total_len;
357 size_t diff;
358
359 total_len = hsize + len;
360
361 if (total_len > psinfo->bufsize) {
362 diff = total_len - psinfo->bufsize + hsize;
363 memcpy(psinfo->buf, big_oops_buf, hsize);
364 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
365 psinfo->bufsize - hsize);
366 total_len = psinfo->bufsize;
367 } else
368 memcpy(psinfo->buf, big_oops_buf, total_len);
369
370 return total_len;
371 }
372
pstore_record_init(struct pstore_record * record,struct pstore_info * psinfo)373 void pstore_record_init(struct pstore_record *record,
374 struct pstore_info *psinfo)
375 {
376 memset(record, 0, sizeof(*record));
377
378 record->psi = psinfo;
379
380 /* Report zeroed timestamp if called before timekeeping has resumed. */
381 record->time = ns_to_timespec64(ktime_get_real_fast_ns());
382 }
383
384 /*
385 * callback from kmsg_dump. Save as much as we can (up to kmsg_bytes) from the
386 * end of the buffer.
387 */
pstore_dump(struct kmsg_dumper * dumper,enum kmsg_dump_reason reason)388 static void pstore_dump(struct kmsg_dumper *dumper,
389 enum kmsg_dump_reason reason)
390 {
391 unsigned long total = 0;
392 const char *why;
393 unsigned int part = 1;
394 int ret;
395
396 why = kmsg_dump_reason_str(reason);
397
398 if (down_trylock(&psinfo->buf_lock)) {
399 /* Failed to acquire lock: give up if we cannot wait. */
400 if (pstore_cannot_wait(reason)) {
401 pr_err("dump skipped in %s path: may corrupt error record\n",
402 in_nmi() ? "NMI" : why);
403 return;
404 }
405 if (down_interruptible(&psinfo->buf_lock)) {
406 pr_err("could not grab semaphore?!\n");
407 return;
408 }
409 }
410
411 oopscount++;
412 while (total < kmsg_bytes) {
413 char *dst;
414 size_t dst_size;
415 int header_size;
416 int zipped_len = -1;
417 size_t dump_size;
418 struct pstore_record record;
419
420 pstore_record_init(&record, psinfo);
421 record.type = PSTORE_TYPE_DMESG;
422 record.count = oopscount;
423 record.reason = reason;
424 record.part = part;
425 record.buf = psinfo->buf;
426
427 if (big_oops_buf) {
428 dst = big_oops_buf;
429 dst_size = big_oops_buf_sz;
430 } else {
431 dst = psinfo->buf;
432 dst_size = psinfo->bufsize;
433 }
434
435 /* Write dump header. */
436 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
437 oopscount, part);
438 dst_size -= header_size;
439
440 /* Write dump contents. */
441 if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
442 dst_size, &dump_size))
443 break;
444
445 if (big_oops_buf) {
446 zipped_len = pstore_compress(dst, psinfo->buf,
447 header_size + dump_size,
448 psinfo->bufsize);
449
450 if (zipped_len > 0) {
451 record.compressed = true;
452 record.size = zipped_len;
453 } else {
454 record.size = copy_kmsg_to_buffer(header_size,
455 dump_size);
456 }
457 } else {
458 record.size = header_size + dump_size;
459 }
460
461 ret = psinfo->write(&record);
462 if (ret == 0 && reason == KMSG_DUMP_OOPS) {
463 pstore_new_entry = 1;
464 pstore_timer_kick();
465 }
466
467 total += record.size;
468 part++;
469 }
470
471 up(&psinfo->buf_lock);
472 }
473
474 static struct kmsg_dumper pstore_dumper = {
475 .dump = pstore_dump,
476 };
477
478 /*
479 * Register with kmsg_dump to save last part of console log on panic.
480 */
pstore_register_kmsg(void)481 static void pstore_register_kmsg(void)
482 {
483 kmsg_dump_register(&pstore_dumper);
484 }
485
pstore_unregister_kmsg(void)486 static void pstore_unregister_kmsg(void)
487 {
488 kmsg_dump_unregister(&pstore_dumper);
489 }
490
491 #ifdef CONFIG_PSTORE_CONSOLE
pstore_console_write(struct console * con,const char * s,unsigned c)492 static void pstore_console_write(struct console *con, const char *s, unsigned c)
493 {
494 struct pstore_record record;
495
496 if (!c)
497 return;
498
499 pstore_record_init(&record, psinfo);
500 record.type = PSTORE_TYPE_CONSOLE;
501
502 record.buf = (char *)s;
503 record.size = c;
504 psinfo->write(&record);
505 }
506
507 static struct console pstore_console = {
508 .write = pstore_console_write,
509 .index = -1,
510 };
511
pstore_register_console(void)512 static void pstore_register_console(void)
513 {
514 /* Show which backend is going to get console writes. */
515 strscpy(pstore_console.name, psinfo->name,
516 sizeof(pstore_console.name));
517 /*
518 * Always initialize flags here since prior unregister_console()
519 * calls may have changed settings (specifically CON_ENABLED).
520 */
521 pstore_console.flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME;
522 register_console(&pstore_console);
523 }
524
pstore_unregister_console(void)525 static void pstore_unregister_console(void)
526 {
527 unregister_console(&pstore_console);
528 }
529 #else
pstore_register_console(void)530 static void pstore_register_console(void) {}
pstore_unregister_console(void)531 static void pstore_unregister_console(void) {}
532 #endif
533
pstore_write_user_compat(struct pstore_record * record,const char __user * buf)534 static int pstore_write_user_compat(struct pstore_record *record,
535 const char __user *buf)
536 {
537 int ret = 0;
538
539 if (record->buf)
540 return -EINVAL;
541
542 record->buf = memdup_user(buf, record->size);
543 if (IS_ERR(record->buf)) {
544 ret = PTR_ERR(record->buf);
545 goto out;
546 }
547
548 ret = record->psi->write(record);
549
550 kfree(record->buf);
551 out:
552 record->buf = NULL;
553
554 return unlikely(ret < 0) ? ret : record->size;
555 }
556
557 /*
558 * platform specific persistent storage driver registers with
559 * us here. If pstore is already mounted, call the platform
560 * read function right away to populate the file system. If not
561 * then the pstore mount code will call us later to fill out
562 * the file system.
563 */
pstore_register(struct pstore_info * psi)564 int pstore_register(struct pstore_info *psi)
565 {
566 if (backend && strcmp(backend, psi->name)) {
567 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
568 return -EPERM;
569 }
570
571 /* Sanity check flags. */
572 if (!psi->flags) {
573 pr_warn("backend '%s' must support at least one frontend\n",
574 psi->name);
575 return -EINVAL;
576 }
577
578 /* Check for required functions. */
579 if (!psi->read || !psi->write) {
580 pr_warn("backend '%s' must implement read() and write()\n",
581 psi->name);
582 return -EINVAL;
583 }
584
585 mutex_lock(&psinfo_lock);
586 if (psinfo) {
587 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
588 psinfo->name, psi->name);
589 mutex_unlock(&psinfo_lock);
590 return -EBUSY;
591 }
592
593 if (!psi->write_user)
594 psi->write_user = pstore_write_user_compat;
595 psinfo = psi;
596 mutex_init(&psinfo->read_mutex);
597 sema_init(&psinfo->buf_lock, 1);
598
599 if (psi->flags & PSTORE_FLAGS_DMESG)
600 allocate_buf_for_compression();
601
602 pstore_get_records(0);
603
604 if (psi->flags & PSTORE_FLAGS_DMESG) {
605 pstore_dumper.max_reason = psinfo->max_reason;
606 pstore_register_kmsg();
607 }
608 if (psi->flags & PSTORE_FLAGS_CONSOLE)
609 pstore_register_console();
610 if (psi->flags & PSTORE_FLAGS_FTRACE)
611 pstore_register_ftrace();
612 if (psi->flags & PSTORE_FLAGS_PMSG)
613 pstore_register_pmsg();
614
615 /* Start watching for new records, if desired. */
616 pstore_timer_kick();
617
618 /*
619 * Update the module parameter backend, so it is visible
620 * through /sys/module/pstore/parameters/backend
621 */
622 backend = kstrdup(psi->name, GFP_KERNEL);
623
624 pr_info("Registered %s as persistent store backend\n", psi->name);
625
626 mutex_unlock(&psinfo_lock);
627 return 0;
628 }
629 EXPORT_SYMBOL_GPL(pstore_register);
630
pstore_unregister(struct pstore_info * psi)631 void pstore_unregister(struct pstore_info *psi)
632 {
633 /* It's okay to unregister nothing. */
634 if (!psi)
635 return;
636
637 mutex_lock(&psinfo_lock);
638
639 /* Only one backend can be registered at a time. */
640 if (WARN_ON(psi != psinfo)) {
641 mutex_unlock(&psinfo_lock);
642 return;
643 }
644
645 /* Unregister all callbacks. */
646 if (psi->flags & PSTORE_FLAGS_PMSG)
647 pstore_unregister_pmsg();
648 if (psi->flags & PSTORE_FLAGS_FTRACE)
649 pstore_unregister_ftrace();
650 if (psi->flags & PSTORE_FLAGS_CONSOLE)
651 pstore_unregister_console();
652 if (psi->flags & PSTORE_FLAGS_DMESG)
653 pstore_unregister_kmsg();
654
655 /* Stop timer and make sure all work has finished. */
656 del_timer_sync(&pstore_timer);
657 flush_work(&pstore_work);
658
659 /* Remove all backend records from filesystem tree. */
660 pstore_put_backend_records(psi);
661
662 free_buf_for_compression();
663
664 psinfo = NULL;
665 kfree(backend);
666 backend = NULL;
667 mutex_unlock(&psinfo_lock);
668 }
669 EXPORT_SYMBOL_GPL(pstore_unregister);
670
decompress_record(struct pstore_record * record)671 static void decompress_record(struct pstore_record *record)
672 {
673 int ret;
674 int unzipped_len;
675 char *unzipped, *workspace;
676
677 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !record->compressed)
678 return;
679
680 /* Only PSTORE_TYPE_DMESG support compression. */
681 if (record->type != PSTORE_TYPE_DMESG) {
682 pr_warn("ignored compressed record type %d\n", record->type);
683 return;
684 }
685
686 /* Missing compression buffer means compression was not initialized. */
687 if (!big_oops_buf) {
688 pr_warn("no decompression method initialized!\n");
689 return;
690 }
691
692 /* Allocate enough space to hold max decompression and ECC. */
693 unzipped_len = big_oops_buf_sz;
694 workspace = kmalloc(unzipped_len + record->ecc_notice_size,
695 GFP_KERNEL);
696 if (!workspace)
697 return;
698
699 /* After decompression "unzipped_len" is almost certainly smaller. */
700 ret = crypto_comp_decompress(tfm, record->buf, record->size,
701 workspace, &unzipped_len);
702 if (ret) {
703 pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
704 kfree(workspace);
705 return;
706 }
707
708 /* Append ECC notice to decompressed buffer. */
709 memcpy(workspace + unzipped_len, record->buf + record->size,
710 record->ecc_notice_size);
711
712 /* Copy decompressed contents into an minimum-sized allocation. */
713 unzipped = kmemdup(workspace, unzipped_len + record->ecc_notice_size,
714 GFP_KERNEL);
715 kfree(workspace);
716 if (!unzipped)
717 return;
718
719 /* Swap out compressed contents with decompressed contents. */
720 kfree(record->buf);
721 record->buf = unzipped;
722 record->size = unzipped_len;
723 record->compressed = false;
724 }
725
726 /*
727 * Read all the records from one persistent store backend. Create
728 * files in our filesystem. Don't warn about -EEXIST errors
729 * when we are re-scanning the backing store looking to add new
730 * error records.
731 */
pstore_get_backend_records(struct pstore_info * psi,struct dentry * root,int quiet)732 void pstore_get_backend_records(struct pstore_info *psi,
733 struct dentry *root, int quiet)
734 {
735 int failed = 0;
736 unsigned int stop_loop = 65536;
737
738 if (!psi || !root)
739 return;
740
741 mutex_lock(&psi->read_mutex);
742 if (psi->open && psi->open(psi))
743 goto out;
744
745 /*
746 * Backend callback read() allocates record.buf. decompress_record()
747 * may reallocate record.buf. On success, pstore_mkfile() will keep
748 * the record.buf, so free it only on failure.
749 */
750 for (; stop_loop; stop_loop--) {
751 struct pstore_record *record;
752 int rc;
753
754 record = kzalloc(sizeof(*record), GFP_KERNEL);
755 if (!record) {
756 pr_err("out of memory creating record\n");
757 break;
758 }
759 pstore_record_init(record, psi);
760
761 record->size = psi->read(record);
762
763 /* No more records left in backend? */
764 if (record->size <= 0) {
765 kfree(record);
766 break;
767 }
768
769 decompress_record(record);
770 rc = pstore_mkfile(root, record);
771 if (rc) {
772 /* pstore_mkfile() did not take record, so free it. */
773 kfree(record->buf);
774 kfree(record);
775 if (rc != -EEXIST || !quiet)
776 failed++;
777 }
778 }
779 if (psi->close)
780 psi->close(psi);
781 out:
782 mutex_unlock(&psi->read_mutex);
783
784 if (failed)
785 pr_warn("failed to create %d record(s) from '%s'\n",
786 failed, psi->name);
787 if (!stop_loop)
788 pr_err("looping? Too many records seen from '%s'\n",
789 psi->name);
790 }
791
pstore_dowork(struct work_struct * work)792 static void pstore_dowork(struct work_struct *work)
793 {
794 pstore_get_records(1);
795 }
796
pstore_timefunc(struct timer_list * unused)797 static void pstore_timefunc(struct timer_list *unused)
798 {
799 if (pstore_new_entry) {
800 pstore_new_entry = 0;
801 schedule_work(&pstore_work);
802 }
803
804 pstore_timer_kick();
805 }
806
pstore_choose_compression(void)807 static void __init pstore_choose_compression(void)
808 {
809 const struct pstore_zbackend *step;
810
811 if (!compress)
812 return;
813
814 for (step = zbackends; step->name; step++) {
815 if (!strcmp(compress, step->name)) {
816 zbackend = step;
817 return;
818 }
819 }
820 }
821
pstore_init(void)822 static int __init pstore_init(void)
823 {
824 int ret;
825
826 pstore_choose_compression();
827
828 /*
829 * Check if any pstore backends registered earlier but did not
830 * initialize compression because crypto was not ready. If so,
831 * initialize compression now.
832 */
833 allocate_buf_for_compression();
834
835 ret = pstore_init_fs();
836 if (ret)
837 free_buf_for_compression();
838
839 return ret;
840 }
841 late_initcall(pstore_init);
842
pstore_exit(void)843 static void __exit pstore_exit(void)
844 {
845 pstore_exit_fs();
846 }
847 module_exit(pstore_exit)
848
849 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
850 MODULE_LICENSE("GPL");
851