Erase race?

[Jon Ringle]

On Tue, Apr 13, 2010 at 4:15 PM, Jon Ringle <jon at ringle.org> wrote:
> Hi,
> I have a few machines that have UBI and UBIFS on NOR flash that are
> undergoing continuous reboot testing.
> One of them just caught the following failure:
>
> [   51.250000] IXP4XX-Flash.0: buffer write error (status 0xd0)
> [   51.250000] UBI error: ubi_io_write: error -22 while writing 64
> bytes to PEB 226:0, written 0 bytes
> [   51.270000] UBI error: erase_worker: failed to erase PEB 226, error -22
> [   51.270000] UBI warning: ubi_ro_mode: switch to read-only mode
> [   51.290000] UBI error: do_work: work failed with error code -22
> [   51.290000] UBI error: ubi_thread: ubi_bgt0d: work failed with error code -22
>
> Looking at this it appears that the failure might have been caused due
> to the erase_worker and ubi_io_write occurring out of order... since
> it looks like ubi_io_write was trying to write at offset 0 of the PEB,
> which I imagine would have to be the EC header, which should happen
> after the block is erased. But it doesn't seem to be the case here.

I had this issue occur again on another system:
[   48.250000] IXP4XX-Flash.0: buffer write error (status 0xd0)
[   48.250000] UBI error: ubi_io_write: error -22 while writing 64
bytes to PEB 111:0, written 0 bytes
[   48.280000] UBI error: erase_worker: failed to erase PEB 111, error -22
[   48.280000] UBI warning: ubi_ro_mode: switch to read-only mode
[   48.310000] UBI error: do_work: work failed with error code -22
[   48.310000] UBI error: ubi_thread: ubi_bgt0d: work failed with error code -22

Can anyone comment as to my theory that this is a race condition
between ubi_io_write and erase_worker occurring out of order?

Thanks
Jon