scsi: fnic: Finish scsi_cmnd before dropping the spinlock

When aborting a SCSI command through fnic, there is a race with the fnic
interrupt handler which can result in the SCSI command and its request
being completed twice. If the interrupt handler claims the command by
setting CMD_SP to NULL first, the abort handler assumes the interrupt
handler has completed the command and returns SUCCESS, causing the request
for the scsi_cmnd to be re-queued.

But the interrupt handler may not have finished the command yet. After it
drops the spinlock protecting CMD_SP, it does memory cleanup before finally
calling scsi_done() to complete the scsi_cmnd. If the call to scsi_done
occurs after the abort handler finishes and re-queues the request, the
completion of the scsi_cmnd will advance and try to double complete a
request already queued for retry.

This patch fixes the issue by moving scsi_done() and any other use of
scsi_cmnd to before the spinlock is released by the interrupt handler.

Link: https://lore.kernel.org/r/20220311184359.2345319-1-djeffery@redhat.com
Reviewed-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: David Jeffery <djeffery@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>