Add RX OOO completion feature

[mw]

Summary

The RX out of order completion feature, allows to complete RX
descriptors out of order, by keeping trace of all free descriptors in
the separate array.

[mk_semihalf.com]

Remove checking for NULL after calling malloc with M_WAITOK flag

[byenduri_gmail.com]

Curious as to how this was tested since I assume 'out of order RX descriptors' condition is not common.

sys/dev/ena/ena.c

1512 ↗

(On Diff #34669)

nit - suggest removing this 'goto' and moving lines 1534 and 1536 here. It makes it easier to read.

1622 ↗

(On Diff #34669)

Shouldn't this be rx_ring->free_rx_ids?

[mk_semihalf.com]

• Expand goto if retrieving RX mbuf fails
• Fix error handling routine by assigning value to free_rx_ids instead of tx

[mk_semihalf.com]

In D12855#269430, @byenduri_gmail.com wrote:

Curious as to how this was tested since I assume 'out of order RX descriptors' condition is not common.

Yes, it is uncommon but it can be achieved with the packet generator

sys/dev/ena/ena.c

1622 ↗

(On Diff #34669)

Good catch, thanks!

[byenduri_gmail.com]

Looks good to me.