From: Neil Horman <nhorman@tuxdriver.com>
Date: Wed, 3 Jan 2018 05:42:04 -0500

On Tue, Jan 02, 2018 at 09:48:27PM -0500, David Miller wrote:

quoted

And for the RX cases, it allows the RX ring to deplete to empty which
tends to hang most chips.  You need to make the DMA failure detection
early and recycle the RX buffer back to the chip instead of passing
it up to the stack.

Strictly speaking, I think we're ok here, because the dirty_rx counter creates a
contiguous area to refill, and we will just pick up where we left off on the
next napi poll.

If you continually fail the mappings, even NAPI poll, eventually the
RX ring will empty.

I don't think we're ok here.