mtd: mtd_oobtest: generate consistent data for verification

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=be54f8f1c76890f4b6163715aed5a3d0a7309dc2
Commit:     be54f8f1c76890f4b6163715aed5a3d0a7309dc2
Parent:     d66d3519c6732db3b4dea2f0c31c514633e89001
Author:     Akinobu Mita <akinobu.mita at gmail.com>
AuthorDate: Sat Mar 8 00:24:10 2014 +0900
Committer:  Brian Norris <computersforpeace at gmail.com>
CommitDate: Thu Apr 17 22:22:03 2014 -0700

    mtd: mtd_oobtest: generate consistent data for verification
    
    mtd_oobtest writes OOB, read it back and verify.  The verification is
    not correctly done if oobsize is not multiple of 4.  Although the data
    to be written and the data to be compared are generated by several
    prandom_byte_state() calls starting with the same seed, these two are
    generated with the different size and different number of calls.
    
    Due to the implementation of prandom_byte_state() if the size on each
    call is not multiple of 4, the resulting data is not always same.
    
    This fixes it by just calling prandom_byte_state() once and using
    correct range instead of calling it multiple times for each.
    
    Reported-by: George Cherian <george.cherian at ti.com>
    Reported-by: Lothar Waßmann <LW at KARO-electronics.de>
    Tested-by: Lothar Waßmann <LW at KARO-electronics.de>
    Cc: George Cherian <george.cherian at ti.com>
    Cc: Lothar Waßmann <LW at KARO-electronics.de>
    Cc: David Woodhouse <dwmw2 at infradead.org>
    Cc: Lee Jones <lee.jones at linaro.org>
    Cc: linux-mtd at lists.infradead.org
    Signed-off-by: Akinobu Mita <akinobu.mita at gmail.com>
    Signed-off-by: Brian Norris <computersforpeace at gmail.com>
---
 drivers/mtd/tests/oobtest.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/mtd/tests/oobtest.c b/drivers/mtd/tests/oobtest.c
index 2e9e2d1..f19ab1a 100644
--- a/drivers/mtd/tests/oobtest.c
+++ b/drivers/mtd/tests/oobtest.c
@@ -69,8 +69,8 @@ static int write_eraseblock(int ebnum)
 	int err = 0;
 	loff_t addr = ebnum * mtd->erasesize;
 
+	prandom_bytes_state(&rnd_state, writebuf, use_len_max * pgcnt);
 	for (i = 0; i < pgcnt; ++i, addr += mtd->writesize) {
-		prandom_bytes_state(&rnd_state, writebuf, use_len);
 		ops.mode      = MTD_OPS_AUTO_OOB;
 		ops.len       = 0;
 		ops.retlen    = 0;
@@ -78,7 +78,7 @@ static int write_eraseblock(int ebnum)
 		ops.oobretlen = 0;
 		ops.ooboffs   = use_offset;
 		ops.datbuf    = NULL;
-		ops.oobbuf    = writebuf;
+		ops.oobbuf    = writebuf + (use_len_max * i) + use_offset;
 		err = mtd_write_oob(mtd, addr, &ops);
 		if (err || ops.oobretlen != use_len) {
 			pr_err("error: writeoob failed at %#llx\n",
@@ -122,8 +122,8 @@ static int verify_eraseblock(int ebnum)
 	int err = 0;
 	loff_t addr = ebnum * mtd->erasesize;
 
+	prandom_bytes_state(&rnd_state, writebuf, use_len_max * pgcnt);
 	for (i = 0; i < pgcnt; ++i, addr += mtd->writesize) {
-		prandom_bytes_state(&rnd_state, writebuf, use_len);
 		ops.mode      = MTD_OPS_AUTO_OOB;
 		ops.len       = 0;
 		ops.retlen    = 0;
@@ -139,7 +139,8 @@ static int verify_eraseblock(int ebnum)
 			errcnt += 1;
 			return err ? err : -1;
 		}
-		if (memcmp(readbuf, writebuf, use_len)) {
+		if (memcmp(readbuf, writebuf + (use_len_max * i) + use_offset,
+			   use_len)) {
 			pr_err("error: verify failed at %#llx\n",
 			       (long long)addr);
 			errcnt += 1;
@@ -166,7 +167,9 @@ static int verify_eraseblock(int ebnum)
 				errcnt += 1;
 				return err ? err : -1;
 			}
-			if (memcmp(readbuf + use_offset, writebuf, use_len)) {
+			if (memcmp(readbuf + use_offset,
+				   writebuf + (use_len_max * i) + use_offset,
+				   use_len)) {
 				pr_err("error: verify failed at %#llx\n",
 						(long long)addr);
 				errcnt += 1;
@@ -566,8 +569,8 @@ static int __init mtd_oobtest_init(void)
 		if (bbt[i] || bbt[i + 1])
 			continue;
 		addr = (i + 1) * mtd->erasesize - mtd->writesize;
+		prandom_bytes_state(&rnd_state, writebuf, sz * cnt);
 		for (pg = 0; pg < cnt; ++pg) {
-			prandom_bytes_state(&rnd_state, writebuf, sz);
 			ops.mode      = MTD_OPS_AUTO_OOB;
 			ops.len       = 0;
 			ops.retlen    = 0;
@@ -575,7 +578,7 @@ static int __init mtd_oobtest_init(void)
 			ops.oobretlen = 0;
 			ops.ooboffs   = 0;
 			ops.datbuf    = NULL;
-			ops.oobbuf    = writebuf;
+			ops.oobbuf    = writebuf + pg * sz;
 			err = mtd_write_oob(mtd, addr, &ops);
 			if (err)
 				goto out;