mtd: tests: stresstest: bail out if device has not enough eraseblocks

stresstest needs at least two eraseblocks. Bail out gracefully if that
condition is not met. Fixes the following 'division by zero' OOPS:

[  619.100000] mtd_stresstest: MTD device size 131072, eraseblock size 131072, page size 2048, count of eraseblocks 1, pages per eraseblock 64, OOB size 64
[  619.120000] mtd_stresstest: scanning for bad eraseblocks
[  619.120000] mtd_stresstest: scanned 1 eraseblocks, 0 are bad
[  619.130000] mtd_stresstest: doing operations
[  619.130000] mtd_stresstest: 0 operations done
[  619.140000] Division by zero in kernel.
...

caused by

        /* Read or write up 2 eraseblocks at a time - hence 'ebcnt - 1' */
        eb %= (ebcnt - 1);

Cc: stable@kernel.org
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/mtd/tests/mtd_stresstest.c b/drivers/mtd/tests/mtd_stresstest.c
index 52ffd9120e0d..811642fea6b4 100644
--- a/drivers/mtd/tests/mtd_stresstest.c
+++ b/drivers/mtd/tests/mtd_stresstest.c
@@ -284,6 +284,12 @@ static int __init mtd_stresstest_init(void)
                (unsigned long long)mtd->size, mtd->erasesize,
                pgsize, ebcnt, pgcnt, mtd->oobsize);
 
+        if (ebcnt < 2) {
+                printk(PRINT_PREF "error: need at least 2 eraseblocks\n");
+                err = -ENOSPC;
+                goto out_put_mtd;
+        }
+
         /* Read or write up 2 eraseblocks at a time */
         bufsize = mtd->erasesize * 2;
 
@@ -322,6 +328,7 @@ out:
         kfree(bbt);
         vfree(writebuf);
         vfree(readbuf);
+out_put_mtd:
         put_mtd_device(mtd);
         if (err)
                 printk(PRINT_PREF "error %d occurred\n", err);