[SCSI] libsas: fix sas_find_local_phy(), take phy references

In the direct-attached case this routine returns the phy on which this
device was first discovered. Which is broken if we want to support
wide-targets, as this phy reference can become stale even though the
port is still active.

In the expander-attached case this routine tries to lookup the phy by
scanning the attached sas addresses of the parent expander, and BUG_ONs
if it can't find it. However since eh and the libsas workqueue run
independently we can still be attempting device recovery via eh after
libsas has recorded the device as detached. This is even easier to hit
now that eh is blocked while device domain rediscovery takes place, and
that libata is fed more timed out commands increasing the chances that
it will try to recover the ata device.

Arrange for dev->phy to always point to a last known good phy, it may be
stale after the port is torn down, but it will catch up for wide port
reconfigurations, and never be NULL.

Signed-off-by: Dan Williams <[e-mail]>
Signed-off-by: James Bottomley <[e-mail]>

drivers/scsi/aic94xx/aic94xx_tmf.c

···
 int asd_I_T_nexus_reset(struct domain_device *dev)
 {
 	int res, tmp_res, i;
-	struct sas_phy *phy = sas_find_local_phy(dev);
+	struct sas_phy *phy = sas_get_local_phy(dev);
 	/* Standard mandates link reset for ATA  (type 0) and
 	 * hard reset for SSP (type 1) */
 	int reset_type = (dev->dev_type == SATA_DEV ||
···
 	for (i = 0 ; i < 3; i++) {
 		tmp_res = asd_clear_nexus_I_T(dev, NEXUS_PHASE_RESUME);
 		if (tmp_res == TC_RESUME)
-			return res;
+			goto out;
 		msleep(500);
 	}
 
···
 	dev_printk(KERN_ERR, &phy->dev,
 		   "Failed to resume nexus after reset 0x%x\n", tmp_res);
 
-	return TMF_RESP_FUNC_FAILED;
+	res = TMF_RESP_FUNC_FAILED;
+ out:
+	sas_put_local_phy(phy);
+	return res;
 }
 
 static int asd_clear_nexus_I_T_L(struct domain_device *dev, u8 *lun)

drivers/scsi/isci/task.c

···
 static int isci_reset_device(struct isci_host *ihost,
 			     struct isci_remote_device *idev)
 {
-	struct sas_phy *phy = sas_find_local_phy(idev->domain_dev);
+	struct sas_phy *phy = sas_get_local_phy(idev->domain_dev);
 	enum sci_status status;
 	unsigned long flags;
 	int rc;
···
 		dev_dbg(&ihost->pdev->dev,
 			 "%s: sci_remote_device_reset(%p) returned %d!\n",
 			 __func__, idev, status);
-
-		return TMF_RESP_FUNC_FAILED;
+		rc = TMF_RESP_FUNC_FAILED;
+		goto out;
 	}
 	spin_unlock_irqrestore(&ihost->scic_lock, flags);
 
···
 	}
 
 	dev_dbg(&ihost->pdev->dev, "%s: idev %p complete.\n", __func__, idev);
-
+ out:
+	sas_put_local_phy(phy);
 	return rc;
 }
 

drivers/scsi/libsas/sas_ata.c

···
 	struct ata_port *ap = link->ap;
 	struct domain_device *dev = ap->private_data;
 	struct domain_device *ex_dev = dev->parent;
-	struct sas_phy *phy = sas_find_local_phy(dev);
+	struct sas_phy *phy = sas_get_local_phy(dev);
 
 	res = sas_get_phy_attached_sas_addr(ex_dev, phy->number, addr);
+	sas_put_local_phy(phy);
 	/* break the wait early if the expander is unreachable,
 	 * otherwise keep polling
 	 */
···
 			      unsigned long deadline)
 {
 	int ret = 0, res;
+	struct sas_phy *phy;
 	struct ata_port *ap = link->ap;
 	int (*check_ready)(struct ata_link *link);
 	struct domain_device *dev = ap->private_data;
-	struct sas_phy *phy = sas_find_local_phy(dev);
 	struct sas_internal *i = dev_to_sas_internal(dev);
 
 	res = i->dft->lldd_I_T_nexus_reset(dev);
···
 	if (res != TMF_RESP_FUNC_COMPLETE)
 		SAS_DPRINTK("%s: Unable to reset ata device?\n", __func__);
 
+	phy = sas_get_local_phy(dev);
 	if (scsi_is_sas_phy_local(phy))
 		check_ready = local_ata_check_ready;
 	else
 		check_ready = smp_ata_check_ready;
+	sas_put_local_phy(phy);
 
 	ret = ata_wait_after_reset(link, deadline, check_ready);
 	if (ret && ret != -EAGAIN)

drivers/scsi/libsas/sas_discover.c

···
 	memset(port->disc.eeds_a, 0, SAS_ADDR_SIZE);
 	memset(port->disc.eeds_b, 0, SAS_ADDR_SIZE);
 	port->disc.max_level = 0;
+	sas_device_set_phy(dev, port->port);
 
 	dev->rphy = rphy;
 
···
 	if (dev->parent)
 		sas_put_device(dev->parent);
 
+	sas_port_put_phy(dev->phy);
+	dev->phy = NULL;
+
 	/* remove the phys and ports, everything else should be gone */
 	if (dev->dev_type == EDGE_DEV || dev->dev_type == FANOUT_DEV)
 		kfree(dev->ex_dev.ex_phy);
···
 
 	port->port->rphy = NULL;
 
+}
+
+void sas_device_set_phy(struct domain_device *dev, struct sas_port *port)
+{
+	struct sas_ha_struct *ha;
+	struct sas_phy *new_phy;
+
+	if (!dev)
+		return;
+
+	ha = dev->port->ha;
+	new_phy = sas_port_get_phy(port);
+
+	/* pin and record last seen phy */
+	spin_lock_irq(&ha->phy_port_lock);
+	if (new_phy) {
+		sas_port_put_phy(dev->phy);
+		dev->phy = new_phy;
+	}
+	spin_unlock_irq(&ha->phy_port_lock);
 }
 
 /* ---------- Discovery and Revalidation ---------- */

drivers/scsi/libsas/sas_expander.c

···
 		}
 	}
 	sas_ex_get_linkrate(parent, child, phy);
+	sas_device_set_phy(child, phy->port);
 
 #ifdef CONFIG_SCSI_SAS_ATA
 	if ((phy->attached_tproto & SAS_PROTOCOL_STP) || phy->attached_sata_dev) {
···
 {
 	struct expander_device *ex_dev = &parent->ex_dev;
 	struct ex_phy *phy = &ex_dev->ex_phy[phy_id];
-	struct domain_device *child, *n;
+	struct domain_device *child, *n, *found = NULL;
 	if (last) {
 		list_for_each_entry_safe(child, n,
 			&ex_dev->children, siblings) {
···
 					sas_unregister_ex_tree(parent->port, child);
 				else
 					sas_unregister_dev(parent->port, child);
+				found = child;
 				break;
 			}
 		}
···
 	memset(phy->attached_sas_addr, 0, SAS_ADDR_SIZE);
 	if (phy->port) {
 		sas_port_delete_phy(phy->port, phy->phy);
+		sas_device_set_phy(found, phy->port);
 		if (phy->port->num_phys == 0)
 			sas_port_delete(phy->port);
 		phy->port = NULL;

drivers/scsi/libsas/sas_internal.h

···
 			enum phy_func phy_func, struct sas_phy_linkrates *);
 int sas_smp_get_phy_events(struct sas_phy *phy);
 
+void sas_device_set_phy(struct domain_device *dev, struct sas_port *port);
 struct domain_device *sas_find_dev_by_rphy(struct sas_rphy *rphy);
 struct domain_device *sas_ex_to_ata(struct domain_device *ex_dev, int phy_id);
 int sas_get_phy_attached_sas_addr(struct domain_device *dev, int phy_id,

drivers/scsi/libsas/sas_port.c

···
 	port->num_phys++;
 	port->phy_mask |= (1U << phy->id);
 
-	if (!port->phy)
-		port->phy = phy->phy;
-
 	if (*(u64 *)port->attached_sas_addr == 0) {
 		port->class = phy->class;
 		memcpy(port->attached_sas_addr, phy->attached_sas_addr,
···
 		sas_unregister_domain_devices(port);
 		sas_port_delete(port->port);
 		port->port = NULL;
-	} else
+	} else {
 		sas_port_delete_phy(port->port, phy->phy);
+		sas_device_set_phy(dev, port->port);
+	}
 
 	if (si->dft->lldd_port_deformed)
 		si->dft->lldd_port_deformed(phy);

drivers/scsi/libsas/sas_scsi_host.c

···
 	return res;
 }
 
-/* Find the sas_phy that's attached to this device */
-struct sas_phy *sas_find_local_phy(struct domain_device *dev)
+/* take a reference on the last known good phy for this device */
+struct sas_phy *sas_get_local_phy(struct domain_device *dev)
 {
-	struct domain_device *pdev = dev->parent;
-	struct ex_phy *exphy = NULL;
-	int i;
+	struct sas_ha_struct *ha = dev->port->ha;
+	struct sas_phy *phy;
+	unsigned long flags;
 
-	/* Directly attached device */
-	if (!pdev)
-		return dev->port->phy;
+	/* a published domain device always has a valid phy, it may be
+	 * stale, but it is never NULL
+	 */
+	BUG_ON(!dev->phy);
 
-	/* Otherwise look in the expander */
-	for (i = 0; i < pdev->ex_dev.num_phys; i++)
-		if (!memcmp(dev->sas_addr,
-			    pdev->ex_dev.ex_phy[i].attached_sas_addr,
-			    SAS_ADDR_SIZE)) {
-			exphy = &pdev->ex_dev.ex_phy[i];
-			break;
-		}
+	spin_lock_irqsave(&ha->phy_port_lock, flags);
+	phy = dev->phy;
+	get_device(&phy->dev);
+	spin_unlock_irqrestore(&ha->phy_port_lock, flags);
 
-	BUG_ON(!exphy);
-	return exphy->phy;
+	return phy;
 }
-EXPORT_SYMBOL_GPL(sas_find_local_phy);
+EXPORT_SYMBOL_GPL(sas_get_local_phy);
 
 /* Attempt to send a LUN reset message to a device */
 int sas_eh_device_reset_handler(struct scsi_cmnd *cmd)
···
 int sas_eh_bus_reset_handler(struct scsi_cmnd *cmd)
 {
 	struct domain_device *dev = cmd_to_domain_dev(cmd);
-	struct sas_phy *phy = sas_find_local_phy(dev);
+	struct sas_phy *phy = sas_get_local_phy(dev);
 	int res;
 
 	res = sas_phy_reset(phy, 1);
···
 		SAS_DPRINTK("Bus reset of %s failed 0x%x\n",
 			    kobject_name(&phy->dev.kobj),
 			    res);
+	sas_put_local_phy(phy);
+
 	if (res == TMF_RESP_FUNC_SUCC || res == TMF_RESP_FUNC_COMPLETE)
 		return SUCCESS;
 

drivers/scsi/mvsas/mv_sas.c

···
 static int mvs_debug_I_T_nexus_reset(struct domain_device *dev)
 {
 	int rc;
-	struct sas_phy *phy = sas_find_local_phy(dev);
+	struct sas_phy *phy = sas_get_local_phy(dev);
 	int reset_type = (dev->dev_type == SATA_DEV ||
 			(dev->tproto & SAS_PROTOCOL_STP)) ? 0 : 1;
 	rc = sas_phy_reset(phy, reset_type);
+	sas_put_local_phy(phy);
 	msleep(2000);
 	return rc;
 }

drivers/scsi/pm8001/pm8001_sas.c

···
 
 	pm8001_dev = dev->lldd_dev;
 	pm8001_ha = pm8001_find_ha_by_dev(dev);
-	phy = sas_find_local_phy(dev);
+	phy = sas_get_local_phy(dev);
 
 	if (dev_is_sata(dev)) {
 		DECLARE_COMPLETION_ONSTACK(completion_setstate);
-		if (scsi_is_sas_phy_local(phy))
-			return 0;
+		if (scsi_is_sas_phy_local(phy)) {
+			rc = 0;
+			goto out;
+		}
 		rc = sas_phy_reset(phy, 1);
 		msleep(2000);
 		rc = pm8001_exec_internal_task_abort(pm8001_ha, pm8001_dev ,
···
 		rc = PM8001_CHIP_DISP->set_dev_state_req(pm8001_ha,
 			pm8001_dev, 0x01);
 		wait_for_completion(&completion_setstate);
-	} else{
-	rc = sas_phy_reset(phy, 1);
-	msleep(2000);
+	} else {
+		rc = sas_phy_reset(phy, 1);
+		msleep(2000);
 	}
 	PM8001_EH_DBG(pm8001_ha, pm8001_printk(" for device[%x]:rc=%d\n",
 		pm8001_dev->device_id, rc));
+ out:
+	sas_put_local_phy(phy);
 	return rc;
 }
 
···
 	struct pm8001_device *pm8001_dev = dev->lldd_dev;
 	struct pm8001_hba_info *pm8001_ha = pm8001_find_ha_by_dev(dev);
 	if (dev_is_sata(dev)) {
-		struct sas_phy *phy = sas_find_local_phy(dev);
+		struct sas_phy *phy = sas_get_local_phy(dev);
 		rc = pm8001_exec_internal_task_abort(pm8001_ha, pm8001_dev ,
 			dev, 1, 0);
 		rc = sas_phy_reset(phy, 1);
+		sas_put_local_phy(phy);
 		rc = PM8001_CHIP_DISP->set_dev_state_req(pm8001_ha,
 			pm8001_dev, 0x01);
 		msleep(2000);

drivers/scsi/scsi_transport_sas.c

···
 EXPORT_SYMBOL(scsi_is_sas_port);
 
 /**
+ * sas_port_get_phy - try to take a reference on a port member
+ * @port: port to check
+ */
+struct sas_phy *sas_port_get_phy(struct sas_port *port)
+{
+	struct sas_phy *phy;
+
+	mutex_lock(&port->phy_list_mutex);
+	if (list_empty(&port->phy_list))
+		phy = NULL;
+	else {
+		struct list_head *ent = port->phy_list.next;
+
+		phy = list_entry(ent, typeof(*phy), port_siblings);
+		get_device(&phy->dev);
+	}
+	mutex_unlock(&port->phy_list_mutex);
+
+	return phy;
+}
+EXPORT_SYMBOL(sas_port_get_phy);
+
+/**
  * sas_port_add_phy - add another phy to a port to form a wide port
  * @port:	port to add the phy to
  * @phy:	phy to add

include/scsi/libsas.h

···
         struct domain_device *parent;
         struct list_head siblings; /* devices on the same level */
         struct asd_sas_port *port;        /* shortcut to root of the tree */
+	struct sas_phy *phy;
 
         struct list_head dev_list_node;
 	struct list_head disco_list_node; /* awaiting probe or destruct */
···
 	struct list_head destroy_list;
 	enum   sas_linkrate linkrate;
 
-	struct sas_phy *phy;
 	struct work_struct work;
 
 /* public: */
···
 static inline unsigned int to_sas_gpio_od(int device, int bit)
 {
 	return 3 * device + bit;
+}
+
+static inline void sas_put_local_phy(struct sas_phy *phy)
+{
+	put_device(&phy->dev);
 }
 
 #ifdef CONFIG_SCSI_SAS_HOST_SMP
···
 
 extern void sas_ssp_task_response(struct device *dev, struct sas_task *task,
 				  struct ssp_response_iu *iu);
-struct sas_phy *sas_find_local_phy(struct domain_device *dev);
+struct sas_phy *sas_get_local_phy(struct domain_device *dev);
 
 int sas_request_addr(struct Scsi_Host *shost, u8 *addr);
 

include/scsi/scsi_transport_sas.h

···
 void sas_port_delete_phy(struct sas_port *, struct sas_phy *);
 void sas_port_mark_backlink(struct sas_port *);
 int scsi_is_sas_port(const struct device *);
+struct sas_phy *sas_port_get_phy(struct sas_port *port);
+static inline void sas_port_put_phy(struct sas_phy *phy)
+{
+	if (phy)
+		put_device(&phy->dev);
+}
 
 extern struct scsi_transport_template *
 sas_attach_transport(struct sas_function_template *);