[SCSI] scsi_lib_dma: fix bug with dma maps on nested scsi objects

Some of our virtual SCSI hosts don't have a proper bus parent at the
top, which can be a problem for doing DMA on them

This patch makes the host device cache a pointer to the physical bus
device and provides an extra API for setting it (the normal API picks
it up from the parent).  This patch also modifies the qla2xxx and lpfc
vport logic to use the new DMA host setting API.
Acked-By: James Smart  <james.smart@emulex.com>
Cc: Stable Tree <stable@kernel.org>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/scsi/hosts.c

@@ -180,14 +180,20 @@ void scsi_remove_host(struct Scsi_Host *shost)
 EXPORT_SYMBOL(scsi_remove_host);
 
 /**
- * scsi_add_host - add a scsi host
+ * scsi_add_host_with_dma - add a scsi host with dma device
  * @shost:	scsi host pointer to add
  * @dev:	a struct device of type scsi class
+ * @dma_dev:	dma device for the host
+ *
+ * Note: You rarely need to worry about this unless you're in a
+ * virtualised host environments, so use the simpler scsi_add_host()
+ * function instead.
  *
  * Return value: 
  * 	0 on success / != 0 for error
  **/
-int scsi_add_host(struct Scsi_Host *shost, struct device *dev)
+int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
+			   struct device *dma_dev)
 {
 	struct scsi_host_template *sht = shost->hostt;
 	int error = -EINVAL;
@@ -207,6 +213,7 @@ int scsi_add_host(struct Scsi_Host *shost, struct device *dev)
 
 	if (!shost->shost_gendev.parent)
 		shost->shost_gendev.parent = dev ? dev : &platform_bus;
+	shost->dma_dev = dma_dev;
 
 	error = device_add(&shost->shost_gendev);
 	if (error)
@@ -262,7 +269,7 @@ int scsi_add_host(struct Scsi_Host *shost, struct device *dev)
  fail:
 	return error;
 }
-EXPORT_SYMBOL(scsi_add_host);
+EXPORT_SYMBOL(scsi_add_host_with_dma);
 
 static void scsi_host_dev_release(struct device *dev)
 {

drivers/scsi/lpfc/lpfc_init.c

@@ -2408,7 +2408,7 @@ lpfc_create_port(struct lpfc_hba *phba, int instance, struct device *dev)
 	vport->els_tmofunc.function = lpfc_els_timeout;
 	vport->els_tmofunc.data = (unsigned long)vport;
 
-	error = scsi_add_host(shost, dev);
+	error = scsi_add_host_with_dma(shost, dev, &phba->pcidev->dev);
 	if (error)
 		goto out_put_shost;
 

drivers/scsi/qla2xxx/qla_attr.c

@@ -1654,7 +1654,8 @@ qla24xx_vport_create(struct fc_vport *fc_vport, bool disable)
 			fc_vport_set_state(fc_vport, FC_VPORT_LINKDOWN);
 	}
 
-	if (scsi_add_host(vha->host, &fc_vport->dev)) {
+	if (scsi_add_host_with_dma(vha->host, &fc_vport->dev,
+				   &ha->pdev->dev)) {
 		DEBUG15(printk("scsi(%ld): scsi_add_host failure for VP[%d].\n",
 			vha->host_no, vha->vp_idx));
 		goto vport_create_failed_2;

drivers/scsi/scsi_lib_dma.c

@@ -23,7 +23,7 @@ int scsi_dma_map(struct scsi_cmnd *cmd)
 	int nseg = 0;
 
 	if (scsi_sg_count(cmd)) {
-		struct device *dev = cmd->device->host->shost_gendev.parent;
+		struct device *dev = cmd->device->host->dma_dev;
 
 		nseg = dma_map_sg(dev, scsi_sglist(cmd), scsi_sg_count(cmd),
 				  cmd->sc_data_direction);
@@ -41,7 +41,7 @@ EXPORT_SYMBOL(scsi_dma_map);
 void scsi_dma_unmap(struct scsi_cmnd *cmd)
 {
 	if (scsi_sg_count(cmd)) {
-		struct device *dev = cmd->device->host->shost_gendev.parent;
+		struct device *dev = cmd->device->host->dma_dev;
 
 		dma_unmap_sg(dev, scsi_sglist(cmd), scsi_sg_count(cmd),
 			     cmd->sc_data_direction);

include/scsi/scsi_host.h

@@ -682,6 +682,12 @@ struct Scsi_Host {
 	 */
 	void *shost_data;
 
+	/*
+	 * Points to the physical bus device we'd use to do DMA
+	 * Needed just in case we have virtual hosts.
+	 */
+	struct device *dma_dev;
+
 	/*
 	 * We should ensure that this is aligned, both for better performance
 	 * and also because some compilers (m68k) don't automatically force
@@ -726,7 +732,9 @@ extern int scsi_queue_work(struct Scsi_Host *, struct work_struct *);
 extern void scsi_flush_work(struct Scsi_Host *);
 
 extern struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *, int);
-extern int __must_check scsi_add_host(struct Scsi_Host *, struct device *);
+extern int __must_check scsi_add_host_with_dma(struct Scsi_Host *,
+					       struct device *,
+					       struct device *);
 extern void scsi_scan_host(struct Scsi_Host *);
 extern void scsi_rescan_device(struct device *);
 extern void scsi_remove_host(struct Scsi_Host *);
@@ -737,6 +745,12 @@ extern const char *scsi_host_state_name(enum scsi_host_state);
 
 extern u64 scsi_calculate_bounce_limit(struct Scsi_Host *);
 
+static inline int __must_check scsi_add_host(struct Scsi_Host *host,
+					     struct device *dev)
+{
+	return scsi_add_host_with_dma(host, dev, dev);
+}
+
 static inline struct device *scsi_get_device(struct Scsi_Host *shost)
 {
         return shost->shost_gendev.parent;