scsi: lpfc: Fix duplicate unreg_rpi error in port offline flow

scsi: lpfc: Fix duplicate unreg_rpi error in port offline flow

[ Upstream commit 7cfd5639d99bec0d27af089d0c8c114330e43a72 ]

If the driver receives a login that is later then LOGO'd by the remote port
(aka ndlp), the driver, upon the completion of the LOGO ACC transmission,
will logout the node and unregister the rpi that is being used for the
node.  As part of the unreg, the node's rpi value is replaced by the
LPFC_RPI_ALLOC_ERROR value.  If the port is subsequently offlined, the
offline walks the nodes and ensures they are logged out, which possibly
entails unreg'ing their rpi values.  This path does not validate the node's
rpi value, thus doesn't detect that it has been unreg'd already.  The
replaced rpi value is then used when accessing the rpi bitmask array which
tracks active rpi values.  As the LPFC_RPI_ALLOC_ERROR value is not a valid
index for the bitmask, it may fault the system.

Revise the rpi release code to detect when the rpi value is the replaced
RPI_ALLOC_ERROR value and ignore further release steps.

Link: https://lore.kernel.org/r/20191105005708.7399-2-jsmart2021@gmail.com
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>