qla2xxx: Add memory barrier before ringing doorbell.

Signed-off-by: Himanshu Madhani <[e-mail]>
Signed-off-by: Saurav Kashyap <[e-mail]>
Signed-off-by: Christoph Hellwig <[e-mail]>

drivers/scsi/qla2xxx/qla_target.c

···
 	    "qla_target(%d): Sending 24xx Notify Ack %d\n",
 	    vha->vp_idx, nack->u.isp24.status);
 
+	/* Memory Barrier */
+	wmb();
 	qla2x00_start_iocbs(vha, vha->req);
 }
 
···
 
 	vha->vha_tgt.qla_tgt->abts_resp_expected++;
 
+	/* Memory Barrier */
+	wmb();
 	qla2x00_start_iocbs(vha, vha->req);
 }
 
···
 		CTIO7_FLAGS_TERMINATE);
 	ctio->u.status1.ox_id = cpu_to_le16(entry->fcp_hdr_le.ox_id);
 
+	/* Memory Barrier */
+	wmb();
 	qla2x00_start_iocbs(vha, vha->req);
 
 	qlt_24xx_send_abts_resp(vha, (struct abts_recv_from_24xx *)entry,
···
 	ctio->u.status1.response_len = __constant_cpu_to_le16(8);
 	ctio->u.status1.sense_data[0] = resp_code;
 
+	/* Memory Barrier */
+	wmb();
 	qla2x00_start_iocbs(ha, ha->req);
 }
 
···
 	cmd->state = QLA_TGT_STATE_PROCESSED; /* Mid-level is done processing */
 	cmd->cmd_sent_to_fw = 1;
 
+	/* Memory Barrier */
+	wmb();
 	qla2x00_start_iocbs(vha, vha->req);
 	spin_unlock_irqrestore(&ha->hardware_lock, flags);
 
···
 	cmd->state = QLA_TGT_STATE_NEED_DATA;
 	cmd->cmd_sent_to_fw = 1;
 
+	/* Memory Barrier */
+	wmb();
 	qla2x00_start_iocbs(vha, vha->req);
 	spin_unlock_irqrestore(&ha->hardware_lock, flags);
 
···
 	if (ctio24->u.status1.residual != 0)
 		ctio24->u.status1.scsi_status |= SS_RESIDUAL_UNDER;
 
+	/* Memory Barrier */
+	wmb();
 	qla2x00_start_iocbs(vha, vha->req);
 	return ret;
 }
···
 	 */
 	ctio24->u.status1.ox_id = swab16(atio->u.isp24.fcp_hdr.ox_id);
 	ctio24->u.status1.scsi_status = cpu_to_le16(status);
+	/* Memory Barrier */
+	wmb();
 	qla2x00_start_iocbs(vha, vha->req);
 	return 0;
 }