[04/48] mtd: tests: stresstest: bail out if device has not enough eraseblocks

[Greg KH <gregkh@suse.de>]

3.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Wolfram Sang <w.sang@pengutronix.de>

commit 2f4478ccff7df845dc9c0f8996a96373122c4417 upstream.

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);

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 drivers/mtd/tests/mtd_stresstest.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/mtd/tests/mtd_stresstest.c
+++ b/drivers/mtd/tests/mtd_stresstest.c
@@ -277,6 +277,12 @@ static int __init mtd_stresstest_init(vo
 	       (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;
 
@@ -315,6 +321,7 @@ out:
 	kfree(bbt);
 	vfree(writebuf);
 	vfree(readbuf);
+out_put_mtd:
 	put_mtd_device(mtd);
 	if (err)
 		printk(PRINT_PREF "error %d occurred\n", err);