From: Sinan Kaya <[email protected]>
Date: Fri, 23 Mar 2018 12:51:47 -0400
> It could if txdata->tx_db was not a union. There is a data dependency
> between txdata->tx_db.data.prod and txdata->tx_db.raw.
>
> So, no reordering.
I don't see it that way, the code requires that:
txdata->tx_db.data.prod += nbd;
is visible before the doorbell update.
barrier() doesn't provide that.
Neither does writel_relaxed(). However plain writel() does.
Therefore the code is only correct as-is, and your change potentially
adds a reordering problem.
