scsi: qedf: Add more defensive checks for concurrent error conditions

During an uplink toggle test all error handling is done via timeout and
firmware error conditions which can occur concurrently:

 - SCSI layer timeouts
 - Error detect CQEs
 - Firmware detected underruns
 - ABTS timeouts

All these concurrent events require more defensive checks in the driver
including:

 - Check both internally and externally generated aborts to make sure the
   xid is not already been aborted in another context or in cleanup.

 - Check back pointers in qedf_cmd_timeout to verify the context of the
   io_req, fcport and qedf_ctx

 - Check rport state in host reset handler to not reset the whole host
   if the rport is already uploaded or in the process of relogin

 - Check to state for an fcport before initiating a middle path ELS
   request

Signed-off-by: Chad Dupuis <chad.dupuis@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qedf/qedf_els.c

@@ -14,8 +14,8 @@ static int qedf_initiate_els(struct qedf_rport *fcport, unsigned int op,
 	void (*cb_func)(struct qedf_els_cb_arg *cb_arg),
 	struct qedf_els_cb_arg *cb_arg, uint32_t timer_msec)
 {
-	struct qedf_ctx *qedf = fcport->qedf;
-	struct fc_lport *lport = qedf->lport;
+	struct qedf_ctx *qedf;
+	struct fc_lport *lport;
 	struct qedf_ioreq *els_req;
 	struct qedf_mp_req *mp_req;
 	struct fc_frame_header *fc_hdr;
@@ -29,6 +29,15 @@ static int qedf_initiate_els(struct qedf_rport *fcport, unsigned int op,
 	unsigned long flags;
 	u16 sqe_idx;
 
+	if (!fcport) {
+		QEDF_ERR(NULL, "fcport is NULL");
+		rc = -EINVAL;
+		goto els_err;
+	}
+
+	qedf = fcport->qedf;
+	lport = qedf->lport;
+
 	QEDF_INFO(&(qedf->dbg_ctx), QEDF_LOG_ELS, "Sending ELS\n");
 
 	rc = fc_remote_port_chkready(fcport->rport);