mtd: fix broken state in CFI driver caused by FL_SHUTDOWN

THe CFI driver in 2.6.24 kernel is broken.  Not so intensive read/write
operations cause incomplete writes which lead to kernel panics in JFFS2.

We investigated the issue - it is caused by bug in FL_SHUTDOWN parsing code.
Sometimes chip returns -EIO as if it is in FL_SHUTDOWN state when it should
wait in FL_PONT (error in order of conditions).

The following patch fixes the bug in state parsing code of CFI.  Also I've
added comments to notify developers if they want to add new case in future.

Signed-off-by: Alexey Korolev <akorolev@infradead.org>
Reviewed-by: Joern Engel <joern@logfs.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/mtd/chips/cfi_cmdset_0001.c b/drivers/mtd/chips/cfi_cmdset_0001.c
index 47794d2..0080452 100644 (file)
--- a/drivers/mtd/chips/cfi_cmdset_0001.c
+++ b/drivers/mtd/chips/cfi_cmdset_0001.c
@@ -718,7 +718,7 @@ static int chip_ready (struct map_info *map, struct flchip *chip, unsigned long
                        /* Someone else might have been playing with it. */
                        return -EAGAIN;
                }
-
+               /* Fall through */
        case FL_READY:
        case FL_CFI_QUERY:
        case FL_JEDEC_QUERY:
@@ -778,14 +778,14 @@ static int chip_ready (struct map_info *map, struct flchip *chip, unsigned long
                chip->state = FL_READY;
                return 0;
 
+       case FL_SHUTDOWN:
+               /* The machine is rebooting now,so no one can get chip anymore */
+               return -EIO;
        case FL_POINT:
                /* Only if there's no operation suspended... */
                if (mode == FL_READY && chip->oldstate == FL_READY)
                        return 0;
-
-       case FL_SHUTDOWN:
-               /* The machine is rebooting now,so no one can get chip anymore */
-               return -EIO;
+               /* Fall through */
        default:
        sleep:
                set_current_state(TASK_UNINTERRUPTIBLE);