Comment 0 for bug 1814095

The following 25Gb Broadcom NIC error was seen on Xenial
running the 4.4.0-141-generic kernel on an amd64 host
seeing moderate-heavy network traffic (just once):

* The bnxt_en_po driver froze on a "TX timed out" error
  and triggered the Netdev Watchdog timer under load.

* From kernel log:
  "NETDEV WATCHDOG: eno2d1 (bnxt_en_bpo): transmit queue 0 timed out"
  See attached kern.log excerpt file for full excerpt of error log.

* Release = Xenial
  Kernel = 4.4.0-141-generic #167
  eno2d1 = Product Name: Broadcom Adv. Dual 25Gb Ethernet

* This caused the driver to reset in order to recover:

  "bnxt_en_bpo 0000:19:00.1 eno2d1: TX timeout detected, starting reset task!"

  driver: bnxt_en_bpo
  version: 1.8.1
  source: ubuntu/bnxt/bnxt.c: bnxt_tx_timeout()

* The loss of connectivity and softirq stall caused other failures
  on the system.

* The bnxt_en_po driver is the imported Broadcom driver
  pulled in to support newer Broadcom HW (specific boards)
  while the bnx_en module continues to support the older
  HW. The current Linux upstream driver does not compile
  easily with the 4.4 kernel (too many changes).

* This upstream and bnxt_en driver fix is a likely solution:
   "bnxt_en: Fix TX timeout during netpoll"
   commit: 73f21c653f930f438d53eed29b5e4c65c8a0f906

  This fix has not been applied to the bnxt_en_po driver
  version, but review of the code indicates that it is
  susceptible to the bug, and the fix would be reasonable.

* No easy way to reproduce this