NTB: MFV 113bf1c9: BWD Link Recovery

NTB: MFV 113bf1c9: BWD Link Recovery

The BWD NTB device will drop the link if an error is encountered on the
point-to-point PCI bridge.  The link will stay down until all errors are
cleared and the link is re-established.  On link down, check to see if
the error is detected, if so do the necessary housekeeping to try and
recover from the error and reestablish the link.

There is a potential race between the 2 NTB devices recovering at the
same time.  If the times are synchronized, the link will not recover and
the driver will be stuck in this loop forever.  Add a random interval to
the recovery time to prevent this race.

Authored by:	Jon Mason
Obtained from:	Linux
Sponsored by:	EMC / Isilon Storage Division