[MTD] [INFTL] Fix infinite loop in INFTL_foldchain

When iterating over a chain in reverse (oldest block first), this
patch correctly marks the PUtable[] entry of the second to last erase
block of a chain as BLOCK_NIL, regardless of whether or not it can
format the last block successfully. Before, the second to last block
was only marked as pointing to BLOCK_NIL if INFTL_formatblock()
succeeded on the last block of the chain, which could potentially
result in an infinite loop if the block was worn out and refused to
format.

Signed-off-by: Daniel Rosenthal <danielrosenthal@acm.org>
Acked-by: Greg Ungerer <gerg@snapgear.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/mtd/inftlcore.c b/drivers/mtd/inftlcore.c
index c4f9d3378b24..50ce13887f63 100644
--- a/drivers/mtd/inftlcore.c
+++ b/drivers/mtd/inftlcore.c
@@ -388,6 +388,10 @@ static u16 INFTL_foldchain(struct INFTLrecord *inftl, unsigned thisVUC, unsigned
                 if (thisEUN == targetEUN)
                         break;
 
+                /* Unlink the last block from the chain. */
+                inftl->PUtable[prevEUN] = BLOCK_NIL;
+
+                /* Now try to erase it. */
                 if (INFTL_formatblock(inftl, thisEUN) < 0) {
                         /*
                          * Could not erase : mark block as reserved.
@@ -396,7 +400,6 @@ static u16 INFTL_foldchain(struct INFTLrecord *inftl, unsigned thisVUC, unsigned
                 } else {
                         /* Correctly erased : mark it as free */
                         inftl->PUtable[thisEUN] = BLOCK_FREE;
-                        inftl->PUtable[prevEUN] = BLOCK_NIL;
                         inftl->numfreeEUNs++;
                 }
         }