cxgbe: Add a struct sge_ofld_txq type.

[jhb]

Summary

This type mirrors struct sge_ofld_rxq and holds state for TCP offload
transmit queues. Currently it only holds a work queue but will
include additional state in future changes.

Sponsored by: Chelsio Communications

[jhb]

• Add alloc/free_ofld_txq() routines.

[np]

The offload tx queues are also used for RATELIMIT tx and we should either set cxgbe_rate_tag->eo_txq to ofld_txq->wrq in ethofld_transmit or change eo_txq to be a sge_ofld_txq.

[np]

There's also this in t4_main.c that needs to be updated to sizeof(struct sge_ofld_txq):

s->ofld_txq = malloc(s->nofldtxq * sizeof(struct sge_wrq),  M_CXGBE, M_ZERO | M_WAITOK);

[jhb]

• Fix with RATELIMIT and malloc size.

[jhb]

sys/dev/cxgbe/t4_main.c

1337

Using 'sizeof(*s->ofld_txq)' here instead of the type would perhaps have been more future proof.

sys/dev/cxgbe/t4_sge.c

6447

I changed the type of cst->eo_txq so that this line would still work (and it also seemed more natural for eo_txq to point to the actual txq rather than just the embedded wrq).

[np]

Let's land this if it's ready.