scsi: libsas: Keep host active while processing events

scsi: libsas: Keep host active while processing events

Processing events such as PORTE_BROADCAST_RCVD may cause dependency issues
for runtime power management support.  Such a problem would be that
handling a PORTE_BROADCAST_RCVD event requires that the host is resumed to
send SMP commands. However, in resuming the host, the phyup events
generated from re-enabling the phys are processed in the same workqueue as
the original PORTE_BROADCAST_RCVD event. As such, the host will never
finish resuming (as it waits for the phyup event processing), and then the
PORTE_BROADCAST_RCVD event can't be processed as the SMP commands are
blocked, and so we have a deadlock.  Solve this problem by ensuring that
libsas keeps the host active until completely finished phy or port events,
such as PORTE_BYTES_DMAED. As such, we don't have to worry about resuming
the host for processing individual SMP commands in this example.

Link: https://lore.kernel.org/r/1639999298-244569-15-git-send-email-chenxiang66@hisilicon.com
Reviewed-by: John Garry <john.garry@huawei.com>
Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>