qlxge(4): Distribute RSS over num_rx_rings with a modulo

[nick_spun.io]

Summary

qls_init_rss() built the RSS indirection table with rss_icb->cq_id[i] = (i & (ha->num_rx_rings - 1)); which assumes num_rx_rings is a power of two. When it is not, the AND mask leaves some completion queues with no entries and skews the hash
distribution.

MAX_RX_RINGS is currently hardcoded to 1, so this is latent today, but use a modulo so the table stays correct if the ring count is ever raised to a non-power-of-two value.

[nick_spun.io]

This comment was removed by nick_spun.io.

[adrian]

How's this relate to D57240 ?

[nick_spun.io]

Same bug assuming the number of queues from iflib will be a power of two, was the only other network driver I found with the same bug