xref: /linux/drivers/mtd/tests/oobtest.c (revision 005438a8eef063495ac059d128eea71b58de50e5)
1 /*
2  * Copyright (C) 2006-2008 Nokia Corporation
3  *
4  * This program is free software; you can redistribute it and/or modify it
5  * under the terms of the GNU General Public License version 2 as published by
6  * the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful, but WITHOUT
9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
11  * more details.
12  *
13  * You should have received a copy of the GNU General Public License along with
14  * this program; see the file COPYING. If not, write to the Free Software
15  * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
16  *
17  * Test OOB read and write on MTD device.
18  *
19  * Author: Adrian Hunter <ext-adrian.hunter@nokia.com>
20  */
21 
22 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
23 
24 #include <asm/div64.h>
25 #include <linux/init.h>
26 #include <linux/module.h>
27 #include <linux/moduleparam.h>
28 #include <linux/err.h>
29 #include <linux/mtd/mtd.h>
30 #include <linux/slab.h>
31 #include <linux/sched.h>
32 #include <linux/random.h>
33 
34 #include "mtd_test.h"
35 
36 static int dev = -EINVAL;
37 static int bitflip_limit;
38 module_param(dev, int, S_IRUGO);
39 MODULE_PARM_DESC(dev, "MTD device number to use");
40 module_param(bitflip_limit, int, S_IRUGO);
41 MODULE_PARM_DESC(bitflip_limit, "Max. allowed bitflips per page");
42 
43 static struct mtd_info *mtd;
44 static unsigned char *readbuf;
45 static unsigned char *writebuf;
46 static unsigned char *bbt;
47 
48 static int ebcnt;
49 static int pgcnt;
50 static int errcnt;
51 static int use_offset;
52 static int use_len;
53 static int use_len_max;
54 static int vary_offset;
55 static struct rnd_state rnd_state;
56 
57 static void do_vary_offset(void)
58 {
59 	use_len -= 1;
60 	if (use_len < 1) {
61 		use_offset += 1;
62 		if (use_offset >= use_len_max)
63 			use_offset = 0;
64 		use_len = use_len_max - use_offset;
65 	}
66 }
67 
68 static int write_eraseblock(int ebnum)
69 {
70 	int i;
71 	struct mtd_oob_ops ops;
72 	int err = 0;
73 	loff_t addr = (loff_t)ebnum * mtd->erasesize;
74 
75 	prandom_bytes_state(&rnd_state, writebuf, use_len_max * pgcnt);
76 	for (i = 0; i < pgcnt; ++i, addr += mtd->writesize) {
77 		ops.mode      = MTD_OPS_AUTO_OOB;
78 		ops.len       = 0;
79 		ops.retlen    = 0;
80 		ops.ooblen    = use_len;
81 		ops.oobretlen = 0;
82 		ops.ooboffs   = use_offset;
83 		ops.datbuf    = NULL;
84 		ops.oobbuf    = writebuf + (use_len_max * i) + use_offset;
85 		err = mtd_write_oob(mtd, addr, &ops);
86 		if (err || ops.oobretlen != use_len) {
87 			pr_err("error: writeoob failed at %#llx\n",
88 			       (long long)addr);
89 			pr_err("error: use_len %d, use_offset %d\n",
90 			       use_len, use_offset);
91 			errcnt += 1;
92 			return err ? err : -1;
93 		}
94 		if (vary_offset)
95 			do_vary_offset();
96 	}
97 
98 	return err;
99 }
100 
101 static int write_whole_device(void)
102 {
103 	int err;
104 	unsigned int i;
105 
106 	pr_info("writing OOBs of whole device\n");
107 	for (i = 0; i < ebcnt; ++i) {
108 		if (bbt[i])
109 			continue;
110 		err = write_eraseblock(i);
111 		if (err)
112 			return err;
113 		if (i % 256 == 0)
114 			pr_info("written up to eraseblock %u\n", i);
115 
116 		err = mtdtest_relax();
117 		if (err)
118 			return err;
119 	}
120 	pr_info("written %u eraseblocks\n", i);
121 	return 0;
122 }
123 
124 /*
125  * Display the address, offset and data bytes at comparison failure.
126  * Return number of bitflips encountered.
127  */
128 static size_t memcmpshow(loff_t addr, const void *cs, const void *ct, size_t count)
129 {
130 	const unsigned char *su1, *su2;
131 	int res;
132 	size_t i = 0;
133 	size_t bitflips = 0;
134 
135 	for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--, i++) {
136 		res = *su1 ^ *su2;
137 		if (res) {
138 			pr_info("error @addr[0x%lx:0x%zx] 0x%x -> 0x%x diff 0x%x\n",
139 				(unsigned long)addr, i, *su1, *su2, res);
140 			bitflips += hweight8(res);
141 		}
142 	}
143 
144 	return bitflips;
145 }
146 
147 /*
148  * Compare with 0xff and show the address, offset and data bytes at
149  * comparison failure. Return number of bitflips encountered.
150  */
151 static size_t memffshow(loff_t addr, loff_t offset, const void *cs,
152 			size_t count)
153 {
154 	const unsigned char *su1;
155 	int res;
156 	size_t i = 0;
157 	size_t bitflips = 0;
158 
159 	for (su1 = cs; 0 < count; ++su1, count--, i++) {
160 		res = *su1 ^ 0xff;
161 		if (res) {
162 			pr_info("error @addr[0x%lx:0x%lx] 0x%x -> 0xff diff 0x%x\n",
163 				(unsigned long)addr, (unsigned long)offset + i,
164 				*su1, res);
165 			bitflips += hweight8(res);
166 		}
167 	}
168 
169 	return bitflips;
170 }
171 
172 static int verify_eraseblock(int ebnum)
173 {
174 	int i;
175 	struct mtd_oob_ops ops;
176 	int err = 0;
177 	loff_t addr = (loff_t)ebnum * mtd->erasesize;
178 	size_t bitflips;
179 
180 	prandom_bytes_state(&rnd_state, writebuf, use_len_max * pgcnt);
181 	for (i = 0; i < pgcnt; ++i, addr += mtd->writesize) {
182 		ops.mode      = MTD_OPS_AUTO_OOB;
183 		ops.len       = 0;
184 		ops.retlen    = 0;
185 		ops.ooblen    = use_len;
186 		ops.oobretlen = 0;
187 		ops.ooboffs   = use_offset;
188 		ops.datbuf    = NULL;
189 		ops.oobbuf    = readbuf;
190 		err = mtd_read_oob(mtd, addr, &ops);
191 		if (err || ops.oobretlen != use_len) {
192 			pr_err("error: readoob failed at %#llx\n",
193 			       (long long)addr);
194 			errcnt += 1;
195 			return err ? err : -1;
196 		}
197 
198 		bitflips = memcmpshow(addr, readbuf,
199 				      writebuf + (use_len_max * i) + use_offset,
200 				      use_len);
201 		if (bitflips > bitflip_limit) {
202 			pr_err("error: verify failed at %#llx\n",
203 			       (long long)addr);
204 			errcnt += 1;
205 			if (errcnt > 1000) {
206 				pr_err("error: too many errors\n");
207 				return -1;
208 			}
209 		} else if (bitflips) {
210 			pr_info("ignoring error as within bitflip_limit\n");
211 		}
212 
213 		if (use_offset != 0 || use_len < mtd->ecclayout->oobavail) {
214 			int k;
215 
216 			ops.mode      = MTD_OPS_AUTO_OOB;
217 			ops.len       = 0;
218 			ops.retlen    = 0;
219 			ops.ooblen    = mtd->ecclayout->oobavail;
220 			ops.oobretlen = 0;
221 			ops.ooboffs   = 0;
222 			ops.datbuf    = NULL;
223 			ops.oobbuf    = readbuf;
224 			err = mtd_read_oob(mtd, addr, &ops);
225 			if (err || ops.oobretlen != mtd->ecclayout->oobavail) {
226 				pr_err("error: readoob failed at %#llx\n",
227 						(long long)addr);
228 				errcnt += 1;
229 				return err ? err : -1;
230 			}
231 			bitflips = memcmpshow(addr, readbuf + use_offset,
232 					      writebuf + (use_len_max * i) + use_offset,
233 					      use_len);
234 
235 			/* verify pre-offset area for 0xff */
236 			bitflips += memffshow(addr, 0, readbuf, use_offset);
237 
238 			/* verify post-(use_offset + use_len) area for 0xff */
239 			k = use_offset + use_len;
240 			bitflips += memffshow(addr, k, readbuf + k,
241 					      mtd->ecclayout->oobavail - k);
242 
243 			if (bitflips > bitflip_limit) {
244 				pr_err("error: verify failed at %#llx\n",
245 						(long long)addr);
246 				errcnt += 1;
247 				if (errcnt > 1000) {
248 					pr_err("error: too many errors\n");
249 					return -1;
250 				}
251 			} else if (bitflips) {
252 				pr_info("ignoring errors as within bitflip limit\n");
253 			}
254 		}
255 		if (vary_offset)
256 			do_vary_offset();
257 	}
258 	return err;
259 }
260 
261 static int verify_eraseblock_in_one_go(int ebnum)
262 {
263 	struct mtd_oob_ops ops;
264 	int err = 0;
265 	loff_t addr = (loff_t)ebnum * mtd->erasesize;
266 	size_t len = mtd->ecclayout->oobavail * pgcnt;
267 	size_t oobavail = mtd->ecclayout->oobavail;
268 	size_t bitflips;
269 	int i;
270 
271 	prandom_bytes_state(&rnd_state, writebuf, len);
272 	ops.mode      = MTD_OPS_AUTO_OOB;
273 	ops.len       = 0;
274 	ops.retlen    = 0;
275 	ops.ooblen    = len;
276 	ops.oobretlen = 0;
277 	ops.ooboffs   = 0;
278 	ops.datbuf    = NULL;
279 	ops.oobbuf    = readbuf;
280 
281 	/* read entire block's OOB at one go */
282 	err = mtd_read_oob(mtd, addr, &ops);
283 	if (err || ops.oobretlen != len) {
284 		pr_err("error: readoob failed at %#llx\n",
285 		       (long long)addr);
286 		errcnt += 1;
287 		return err ? err : -1;
288 	}
289 
290 	/* verify one page OOB at a time for bitflip per page limit check */
291 	for (i = 0; i < pgcnt; ++i, addr += mtd->writesize) {
292 		bitflips = memcmpshow(addr, readbuf + (i * oobavail),
293 				      writebuf + (i * oobavail), oobavail);
294 		if (bitflips > bitflip_limit) {
295 			pr_err("error: verify failed at %#llx\n",
296 			       (long long)addr);
297 			errcnt += 1;
298 			if (errcnt > 1000) {
299 				pr_err("error: too many errors\n");
300 				return -1;
301 			}
302 		} else if (bitflips) {
303 			pr_info("ignoring error as within bitflip_limit\n");
304 		}
305 	}
306 
307 	return err;
308 }
309 
310 static int verify_all_eraseblocks(void)
311 {
312 	int err;
313 	unsigned int i;
314 
315 	pr_info("verifying all eraseblocks\n");
316 	for (i = 0; i < ebcnt; ++i) {
317 		if (bbt[i])
318 			continue;
319 		err = verify_eraseblock(i);
320 		if (err)
321 			return err;
322 		if (i % 256 == 0)
323 			pr_info("verified up to eraseblock %u\n", i);
324 
325 		err = mtdtest_relax();
326 		if (err)
327 			return err;
328 	}
329 	pr_info("verified %u eraseblocks\n", i);
330 	return 0;
331 }
332 
333 static int __init mtd_oobtest_init(void)
334 {
335 	int err = 0;
336 	unsigned int i;
337 	uint64_t tmp;
338 	struct mtd_oob_ops ops;
339 	loff_t addr = 0, addr0;
340 
341 	printk(KERN_INFO "\n");
342 	printk(KERN_INFO "=================================================\n");
343 
344 	if (dev < 0) {
345 		pr_info("Please specify a valid mtd-device via module parameter\n");
346 		pr_crit("CAREFUL: This test wipes all data on the specified MTD device!\n");
347 		return -EINVAL;
348 	}
349 
350 	pr_info("MTD device: %d\n", dev);
351 
352 	mtd = get_mtd_device(NULL, dev);
353 	if (IS_ERR(mtd)) {
354 		err = PTR_ERR(mtd);
355 		pr_err("error: cannot get MTD device\n");
356 		return err;
357 	}
358 
359 	if (!mtd_type_is_nand(mtd)) {
360 		pr_info("this test requires NAND flash\n");
361 		goto out;
362 	}
363 
364 	tmp = mtd->size;
365 	do_div(tmp, mtd->erasesize);
366 	ebcnt = tmp;
367 	pgcnt = mtd->erasesize / mtd->writesize;
368 
369 	pr_info("MTD device size %llu, eraseblock size %u, "
370 	       "page size %u, count of eraseblocks %u, pages per "
371 	       "eraseblock %u, OOB size %u\n",
372 	       (unsigned long long)mtd->size, mtd->erasesize,
373 	       mtd->writesize, ebcnt, pgcnt, mtd->oobsize);
374 
375 	err = -ENOMEM;
376 	readbuf = kmalloc(mtd->erasesize, GFP_KERNEL);
377 	if (!readbuf)
378 		goto out;
379 	writebuf = kmalloc(mtd->erasesize, GFP_KERNEL);
380 	if (!writebuf)
381 		goto out;
382 	bbt = kzalloc(ebcnt, GFP_KERNEL);
383 	if (!bbt)
384 		goto out;
385 
386 	err = mtdtest_scan_for_bad_eraseblocks(mtd, bbt, 0, ebcnt);
387 	if (err)
388 		goto out;
389 
390 	use_offset = 0;
391 	use_len = mtd->ecclayout->oobavail;
392 	use_len_max = mtd->ecclayout->oobavail;
393 	vary_offset = 0;
394 
395 	/* First test: write all OOB, read it back and verify */
396 	pr_info("test 1 of 5\n");
397 
398 	err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
399 	if (err)
400 		goto out;
401 
402 	prandom_seed_state(&rnd_state, 1);
403 	err = write_whole_device();
404 	if (err)
405 		goto out;
406 
407 	prandom_seed_state(&rnd_state, 1);
408 	err = verify_all_eraseblocks();
409 	if (err)
410 		goto out;
411 
412 	/*
413 	 * Second test: write all OOB, a block at a time, read it back and
414 	 * verify.
415 	 */
416 	pr_info("test 2 of 5\n");
417 
418 	err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
419 	if (err)
420 		goto out;
421 
422 	prandom_seed_state(&rnd_state, 3);
423 	err = write_whole_device();
424 	if (err)
425 		goto out;
426 
427 	/* Check all eraseblocks */
428 	prandom_seed_state(&rnd_state, 3);
429 	pr_info("verifying all eraseblocks\n");
430 	for (i = 0; i < ebcnt; ++i) {
431 		if (bbt[i])
432 			continue;
433 		err = verify_eraseblock_in_one_go(i);
434 		if (err)
435 			goto out;
436 		if (i % 256 == 0)
437 			pr_info("verified up to eraseblock %u\n", i);
438 
439 		err = mtdtest_relax();
440 		if (err)
441 			goto out;
442 	}
443 	pr_info("verified %u eraseblocks\n", i);
444 
445 	/*
446 	 * Third test: write OOB at varying offsets and lengths, read it back
447 	 * and verify.
448 	 */
449 	pr_info("test 3 of 5\n");
450 
451 	err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
452 	if (err)
453 		goto out;
454 
455 	/* Write all eraseblocks */
456 	use_offset = 0;
457 	use_len = mtd->ecclayout->oobavail;
458 	use_len_max = mtd->ecclayout->oobavail;
459 	vary_offset = 1;
460 	prandom_seed_state(&rnd_state, 5);
461 
462 	err = write_whole_device();
463 	if (err)
464 		goto out;
465 
466 	/* Check all eraseblocks */
467 	use_offset = 0;
468 	use_len = mtd->ecclayout->oobavail;
469 	use_len_max = mtd->ecclayout->oobavail;
470 	vary_offset = 1;
471 	prandom_seed_state(&rnd_state, 5);
472 	err = verify_all_eraseblocks();
473 	if (err)
474 		goto out;
475 
476 	use_offset = 0;
477 	use_len = mtd->ecclayout->oobavail;
478 	use_len_max = mtd->ecclayout->oobavail;
479 	vary_offset = 0;
480 
481 	/* Fourth test: try to write off end of device */
482 	pr_info("test 4 of 5\n");
483 
484 	err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
485 	if (err)
486 		goto out;
487 
488 	addr0 = 0;
489 	for (i = 0; i < ebcnt && bbt[i]; ++i)
490 		addr0 += mtd->erasesize;
491 
492 	/* Attempt to write off end of OOB */
493 	ops.mode      = MTD_OPS_AUTO_OOB;
494 	ops.len       = 0;
495 	ops.retlen    = 0;
496 	ops.ooblen    = 1;
497 	ops.oobretlen = 0;
498 	ops.ooboffs   = mtd->ecclayout->oobavail;
499 	ops.datbuf    = NULL;
500 	ops.oobbuf    = writebuf;
501 	pr_info("attempting to start write past end of OOB\n");
502 	pr_info("an error is expected...\n");
503 	err = mtd_write_oob(mtd, addr0, &ops);
504 	if (err) {
505 		pr_info("error occurred as expected\n");
506 		err = 0;
507 	} else {
508 		pr_err("error: can write past end of OOB\n");
509 		errcnt += 1;
510 	}
511 
512 	/* Attempt to read off end of OOB */
513 	ops.mode      = MTD_OPS_AUTO_OOB;
514 	ops.len       = 0;
515 	ops.retlen    = 0;
516 	ops.ooblen    = 1;
517 	ops.oobretlen = 0;
518 	ops.ooboffs   = mtd->ecclayout->oobavail;
519 	ops.datbuf    = NULL;
520 	ops.oobbuf    = readbuf;
521 	pr_info("attempting to start read past end of OOB\n");
522 	pr_info("an error is expected...\n");
523 	err = mtd_read_oob(mtd, addr0, &ops);
524 	if (err) {
525 		pr_info("error occurred as expected\n");
526 		err = 0;
527 	} else {
528 		pr_err("error: can read past end of OOB\n");
529 		errcnt += 1;
530 	}
531 
532 	if (bbt[ebcnt - 1])
533 		pr_info("skipping end of device tests because last "
534 		       "block is bad\n");
535 	else {
536 		/* Attempt to write off end of device */
537 		ops.mode      = MTD_OPS_AUTO_OOB;
538 		ops.len       = 0;
539 		ops.retlen    = 0;
540 		ops.ooblen    = mtd->ecclayout->oobavail + 1;
541 		ops.oobretlen = 0;
542 		ops.ooboffs   = 0;
543 		ops.datbuf    = NULL;
544 		ops.oobbuf    = writebuf;
545 		pr_info("attempting to write past end of device\n");
546 		pr_info("an error is expected...\n");
547 		err = mtd_write_oob(mtd, mtd->size - mtd->writesize, &ops);
548 		if (err) {
549 			pr_info("error occurred as expected\n");
550 			err = 0;
551 		} else {
552 			pr_err("error: wrote past end of device\n");
553 			errcnt += 1;
554 		}
555 
556 		/* Attempt to read off end of device */
557 		ops.mode      = MTD_OPS_AUTO_OOB;
558 		ops.len       = 0;
559 		ops.retlen    = 0;
560 		ops.ooblen    = mtd->ecclayout->oobavail + 1;
561 		ops.oobretlen = 0;
562 		ops.ooboffs   = 0;
563 		ops.datbuf    = NULL;
564 		ops.oobbuf    = readbuf;
565 		pr_info("attempting to read past end of device\n");
566 		pr_info("an error is expected...\n");
567 		err = mtd_read_oob(mtd, mtd->size - mtd->writesize, &ops);
568 		if (err) {
569 			pr_info("error occurred as expected\n");
570 			err = 0;
571 		} else {
572 			pr_err("error: read past end of device\n");
573 			errcnt += 1;
574 		}
575 
576 		err = mtdtest_erase_eraseblock(mtd, ebcnt - 1);
577 		if (err)
578 			goto out;
579 
580 		/* Attempt to write off end of device */
581 		ops.mode      = MTD_OPS_AUTO_OOB;
582 		ops.len       = 0;
583 		ops.retlen    = 0;
584 		ops.ooblen    = mtd->ecclayout->oobavail;
585 		ops.oobretlen = 0;
586 		ops.ooboffs   = 1;
587 		ops.datbuf    = NULL;
588 		ops.oobbuf    = writebuf;
589 		pr_info("attempting to write past end of device\n");
590 		pr_info("an error is expected...\n");
591 		err = mtd_write_oob(mtd, mtd->size - mtd->writesize, &ops);
592 		if (err) {
593 			pr_info("error occurred as expected\n");
594 			err = 0;
595 		} else {
596 			pr_err("error: wrote past end of device\n");
597 			errcnt += 1;
598 		}
599 
600 		/* Attempt to read off end of device */
601 		ops.mode      = MTD_OPS_AUTO_OOB;
602 		ops.len       = 0;
603 		ops.retlen    = 0;
604 		ops.ooblen    = mtd->ecclayout->oobavail;
605 		ops.oobretlen = 0;
606 		ops.ooboffs   = 1;
607 		ops.datbuf    = NULL;
608 		ops.oobbuf    = readbuf;
609 		pr_info("attempting to read past end of device\n");
610 		pr_info("an error is expected...\n");
611 		err = mtd_read_oob(mtd, mtd->size - mtd->writesize, &ops);
612 		if (err) {
613 			pr_info("error occurred as expected\n");
614 			err = 0;
615 		} else {
616 			pr_err("error: read past end of device\n");
617 			errcnt += 1;
618 		}
619 	}
620 
621 	/* Fifth test: write / read across block boundaries */
622 	pr_info("test 5 of 5\n");
623 
624 	/* Erase all eraseblocks */
625 	err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
626 	if (err)
627 		goto out;
628 
629 	/* Write all eraseblocks */
630 	prandom_seed_state(&rnd_state, 11);
631 	pr_info("writing OOBs of whole device\n");
632 	for (i = 0; i < ebcnt - 1; ++i) {
633 		int cnt = 2;
634 		int pg;
635 		size_t sz = mtd->ecclayout->oobavail;
636 		if (bbt[i] || bbt[i + 1])
637 			continue;
638 		addr = (loff_t)(i + 1) * mtd->erasesize - mtd->writesize;
639 		prandom_bytes_state(&rnd_state, writebuf, sz * cnt);
640 		for (pg = 0; pg < cnt; ++pg) {
641 			ops.mode      = MTD_OPS_AUTO_OOB;
642 			ops.len       = 0;
643 			ops.retlen    = 0;
644 			ops.ooblen    = sz;
645 			ops.oobretlen = 0;
646 			ops.ooboffs   = 0;
647 			ops.datbuf    = NULL;
648 			ops.oobbuf    = writebuf + pg * sz;
649 			err = mtd_write_oob(mtd, addr, &ops);
650 			if (err)
651 				goto out;
652 			if (i % 256 == 0)
653 				pr_info("written up to eraseblock %u\n", i);
654 
655 			err = mtdtest_relax();
656 			if (err)
657 				goto out;
658 
659 			addr += mtd->writesize;
660 		}
661 	}
662 	pr_info("written %u eraseblocks\n", i);
663 
664 	/* Check all eraseblocks */
665 	prandom_seed_state(&rnd_state, 11);
666 	pr_info("verifying all eraseblocks\n");
667 	for (i = 0; i < ebcnt - 1; ++i) {
668 		if (bbt[i] || bbt[i + 1])
669 			continue;
670 		prandom_bytes_state(&rnd_state, writebuf,
671 					mtd->ecclayout->oobavail * 2);
672 		addr = (loff_t)(i + 1) * mtd->erasesize - mtd->writesize;
673 		ops.mode      = MTD_OPS_AUTO_OOB;
674 		ops.len       = 0;
675 		ops.retlen    = 0;
676 		ops.ooblen    = mtd->ecclayout->oobavail * 2;
677 		ops.oobretlen = 0;
678 		ops.ooboffs   = 0;
679 		ops.datbuf    = NULL;
680 		ops.oobbuf    = readbuf;
681 		err = mtd_read_oob(mtd, addr, &ops);
682 		if (err)
683 			goto out;
684 		if (memcmpshow(addr, readbuf, writebuf,
685 			       mtd->ecclayout->oobavail * 2)) {
686 			pr_err("error: verify failed at %#llx\n",
687 			       (long long)addr);
688 			errcnt += 1;
689 			if (errcnt > 1000) {
690 				pr_err("error: too many errors\n");
691 				goto out;
692 			}
693 		}
694 		if (i % 256 == 0)
695 			pr_info("verified up to eraseblock %u\n", i);
696 
697 		err = mtdtest_relax();
698 		if (err)
699 			goto out;
700 	}
701 	pr_info("verified %u eraseblocks\n", i);
702 
703 	pr_info("finished with %d errors\n", errcnt);
704 out:
705 	kfree(bbt);
706 	kfree(writebuf);
707 	kfree(readbuf);
708 	put_mtd_device(mtd);
709 	if (err)
710 		pr_info("error %d occurred\n", err);
711 	printk(KERN_INFO "=================================================\n");
712 	return err;
713 }
714 module_init(mtd_oobtest_init);
715 
716 static void __exit mtd_oobtest_exit(void)
717 {
718 	return;
719 }
720 module_exit(mtd_oobtest_exit);
721 
722 MODULE_DESCRIPTION("Out-of-band test module");
723 MODULE_AUTHOR("Adrian Hunter");
724 MODULE_LICENSE("GPL");
725