Merge branch 'core-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[pandora-kernel.git] / drivers / mtd / ubi / scan.c

diff --git a/drivers/mtd/ubi/scan.c b/drivers/mtd/ubi/scan.c
index f60895e..b847745 100644 (file)
--- a/drivers/mtd/ubi/scan.c
+++ b/drivers/mtd/ubi/scan.c
@@ -781,11 +781,22 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
                        return -EINVAL;
                }
 
-               image_seq = be32_to_cpu(ech->ec);
+               /*
+                * Make sure that all PEBs have the same image sequence number.
+                * This allows us to detect situations when users flash UBI
+                * images incorrectly, so that the flash has the new UBI image
+                * and leftovers from the old one. This feature was added
+                * relatively recently, and the sequence number was always
+                * zero, because old UBI implementations always set it to zero.
+                * For this reasons, we do not panic if some PEBs have zero
+                * sequence number, while other PEBs have non-zero sequence
+                * number.
+                */
+               image_seq = be32_to_cpu(ech->image_seq);
                if (!si->image_seq_set) {
                        ubi->image_seq = image_seq;
                        si->image_seq_set = 1;
-               } else if (ubi->image_seq != image_seq) {
+               } else if (ubi->image_seq && ubi->image_seq != image_seq) {
                        ubi_err("bad image sequence number %d in PEB %d, "
                                "expected %d", image_seq, pnum, ubi->image_seq);
                        ubi_dbg_dump_ec_hdr(ech);