[PATCH 09/12] libsas, libata: fix start of life for a sas ata_port

[Dan Williams <dan.j.williams@intel.com>]

This changes the ordering of initialization and probing events from:
  1/ allocate rphy in PORTE_BYTES_DMAED, DISCE_REVALIDATE_DOMAIN
  2/ allocate ata_port and schedule port probe in DISCE_PROBE
...to:
  1/ allocate ata_port in PORTE_BYTES_DMAED, DISCE_REVALIDATE_DOMAIN
  2/ allocate rphy in PORTE_BYTES_DMAED, DISCE_REVALIDATE_DOMAIN
  3/ schedule port probe in DISCE_PROBE

This ordering prevents PHYE_SIGNAL_LOSS_EVENTS from sneaking in to
destrory ata devices before they have been fully initialized:

  BUG: unable to handle kernel paging request at 0000000000003b10
  IP: [<ffffffffa0053d7e>] sas_ata_end_eh+0x12/0x5e [libsas]
  ...
  [<ffffffffa004d1af>] sas_unregister_common_dev+0x78/0xc9 [libsas]
  [<ffffffffa004d4d4>] sas_unregister_dev+0x4f/0xad [libsas]
  [<ffffffffa004d5b1>] sas_unregister_domain_devices+0x7f/0xbf [libsas]
  [<ffffffffa004c487>] sas_deform_port+0x61/0x1b8 [libsas]
  [<ffffffffa004bed0>] sas_phye_loss_of_signal+0x29/0x2b [libsas]

...and kills the awkward "sata domain_device briefly existing in the
domain without an ata_port" state.

Reported-by: Michal Kosciowski <michal.kosciowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/ata/libata-scsi.c          |   35 ++++++++++++++++++++---------------
 drivers/scsi/ipr.c                 |    6 +++++-
 drivers/scsi/libsas/sas_ata.c      |   33 ++++++++++-----------------------
 drivers/scsi/libsas/sas_discover.c |   13 ++++++++++---
 drivers/scsi/libsas/sas_expander.c |    8 +++++---
 include/linux/libata.h             |    3 ++-
 include/scsi/sas_ata.h             |    4 ++--
 7 files changed, 54 insertions(+), 48 deletions(-)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 93dabdc..cde63f2 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3838,18 +3838,25 @@ void ata_sas_port_stop(struct ata_port *ap)
 }
 EXPORT_SYMBOL_GPL(ata_sas_port_stop);
 
-int ata_sas_async_port_init(struct ata_port *ap)
+/**
+ * ata_sas_async_probe - simply schedule probing and return
+ * @ap: Port to probe
+ *
+ * For batch scheduling of probe for sas attached ata devices, assumes
+ * the port has already been through ata_sas_port_init()
+ */
+void ata_sas_async_probe(struct ata_port *ap)
 {
-	int rc = ap->ops->port_start(ap);
-
-	if (!rc) {
-		ap->print_id = atomic_inc_return(&ata_print_id);
-		__ata_port_probe(ap);
-	}
+	__ata_port_probe(ap);
+}
+EXPORT_SYMBOL_GPL(ata_sas_async_probe);
 
-	return rc;
+int ata_sas_sync_probe(struct ata_port *ap)
+{
+	return ata_port_probe(ap);
 }
-EXPORT_SYMBOL_GPL(ata_sas_async_port_init);
+EXPORT_SYMBOL_GPL(ata_sas_sync_probe);
+
 
 /**
  *	ata_sas_port_init - Initialize a SATA device
@@ -3866,12 +3873,10 @@ int ata_sas_port_init(struct ata_port *ap)
 {
 	int rc = ap->ops->port_start(ap);
 
-	if (!rc) {
-		ap->print_id = atomic_inc_return(&ata_print_id);
-		rc = ata_port_probe(ap);
-	}
-
-	return rc;
+	if (rc)
+		return rc;
+	ap->print_id = atomic_inc_return(&ata_print_id);
+	return 0;
 }
 EXPORT_SYMBOL_GPL(ata_sas_port_init);
 
diff --git a/drivers/scsi/ipr.c b/drivers/scsi/ipr.c
index cdfe5a1..4c49769 100644
--- a/drivers/scsi/ipr.c
+++ b/drivers/scsi/ipr.c
@@ -4546,8 +4546,12 @@ static int ipr_ata_slave_alloc(struct scsi_device *sdev)
 	ENTER;
 	if (sdev->sdev_target)
 		sata_port = sdev->sdev_target->hostdata;
-	if (sata_port)
+	if (sata_port) {
 		rc = ata_sas_port_init(sata_port->ap);
+		if (rc == 0)
+			rc = ata_sas_sync_probe(sata_port->ap);
+	}
+
 	if (rc)
 		ipr_slave_destroy(sdev);
 
diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
index 545b78d..6a6c80f 100644
--- a/drivers/scsi/libsas/sas_ata.c
+++ b/drivers/scsi/libsas/sas_ata.c
@@ -573,11 +573,12 @@ static struct ata_port_info sata_port_info = {
 	.port_ops = &sas_sata_ops
 };
 
-int sas_ata_init_host_and_port(struct domain_device *found_dev)
+int sas_ata_init(struct domain_device *found_dev)
 {
 	struct sas_ha_struct *ha = found_dev->port->ha;
 	struct Scsi_Host *shost = ha->core.shost;
 	struct ata_port *ap;
+	int rc;
 
 	ata_host_init(&found_dev->sata_dev.ata_host,
 		      ha->dev,
@@ -594,8 +595,11 @@ int sas_ata_init_host_and_port(struct domain_device *found_dev)
 	ap->private_data = found_dev;
 	ap->cbl = ATA_CBL_SATA;
 	ap->scsi_host = shost;
-	/* publish initialized ata port */
-	smp_wmb();
+	rc = ata_sas_port_init(ap);
+	if (rc) {
+		ata_sas_port_destroy(ap);
+		return rc;
+	}
 	found_dev->sata_dev.ap = ap;
 
 	return 0;
@@ -674,18 +678,13 @@ static void sas_get_ata_command_set(struct domain_device *dev)
 void sas_probe_sata(struct asd_sas_port *port)
 {
 	struct domain_device *dev, *n;
-	int err;
 
 	mutex_lock(&port->ha->disco_mutex);
-	list_for_each_entry_safe(dev, n, &port->disco_list, disco_list_node) {
+	list_for_each_entry(dev, &port->disco_list, disco_list_node) {
 		if (!dev_is_sata(dev))
 			continue;
 
-		err = sas_ata_init_host_and_port(dev);
-		if (err)
-			sas_fail_probe(dev, __func__, err);
-		else
-			ata_sas_async_port_init(dev->sata_dev.ap);
+		ata_sas_async_probe(dev->sata_dev.ap);
 	}
 	mutex_unlock(&port->ha->disco_mutex);
 
@@ -740,18 +739,6 @@ static void async_sas_ata_eh(void *data, async_cookie_t cookie)
 	sas_put_device(dev);
 }
 
-static bool sas_ata_dev_eh_valid(struct domain_device *dev)
-{
-	struct ata_port *ap;
-
-	if (!dev_is_sata(dev))
-		return false;
-	ap = dev->sata_dev.ap;
-	/* consume fully initialized ata ports */
-	smp_rmb();
-	return !!ap;
-}
-
 void sas_ata_strategy_handler(struct Scsi_Host *shost)
 {
 	struct sas_ha_struct *sas_ha = SHOST_TO_SAS_HA(shost);
@@ -775,7 +762,7 @@ void sas_ata_strategy_handler(struct Scsi_Host *shost)
 
 		spin_lock(&port->dev_list_lock);
 		list_for_each_entry(dev, &port->dev_list, dev_list_node) {
-			if (!sas_ata_dev_eh_valid(dev))
+			if (!dev_is_sata(dev))
 				continue;
 
 			/* hold a reference over eh since we may be
diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
index 128160d..ff497ac 100644
--- a/drivers/scsi/libsas/sas_discover.c
+++ b/drivers/scsi/libsas/sas_discover.c
@@ -72,6 +72,7 @@ static int sas_get_port_device(struct asd_sas_port *port)
 	struct asd_sas_phy *phy;
 	struct sas_rphy *rphy;
 	struct domain_device *dev;
+	int rc = -ENODEV;
 
 	dev = sas_alloc_device();
 	if (!dev)
@@ -110,9 +111,16 @@ static int sas_get_port_device(struct asd_sas_port *port)
 
 	sas_init_dev(dev);
 
+	dev->port = port;
 	switch (dev->dev_type) {
-	case SAS_END_DEV:
 	case SATA_DEV:
+		rc = sas_ata_init(dev);
+		if (rc) {
+			rphy = NULL;
+			break;
+		}
+		/* fall through */
+	case SAS_END_DEV:
 		rphy = sas_end_device_alloc(port->port);
 		break;
 	case EDGE_DEV:
@@ -131,7 +139,7 @@ static int sas_get_port_device(struct asd_sas_port *port)
 
 	if (!rphy) {
 		sas_put_device(dev);
-		return -ENODEV;
+		return rc;
 	}
 
 	rphy->identify.phy_identifier = phy->phy->identify.phy_identifier;
@@ -139,7 +147,6 @@ static int sas_get_port_device(struct asd_sas_port *port)
 	sas_fill_in_rphy(dev, rphy);
 	sas_hash_addr(dev->hashed_sas_addr, dev->sas_addr);
 	port->port_dev = dev;
-	dev->port = port;
 	dev->linkrate = port->linkrate;
 	dev->min_linkrate = port->linkrate;
 	dev->max_linkrate = port->linkrate;
diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index c1f91b1..75247a1 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -790,12 +790,14 @@ static struct domain_device *sas_ex_discover_end_dev(
 		if (res)
 			goto out_free;
 
+		sas_init_dev(child);
+		res = sas_ata_init(child);
+		if (res)
+			goto out_free;
 		rphy = sas_end_device_alloc(phy->port);
-		if (unlikely(!rphy))
+		if (!rphy)
 			goto out_free;
 
-		sas_init_dev(child);
-
 		child->rphy = rphy;
 		get_device(&rphy->dev);
 
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 83ff256..a868bbc 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -998,7 +998,8 @@ extern int ata_sas_scsi_ioctl(struct ata_port *ap, struct scsi_device *dev,
 extern void ata_sas_port_destroy(struct ata_port *);
 extern struct ata_port *ata_sas_port_alloc(struct ata_host *,
 					   struct ata_port_info *, struct Scsi_Host *);
-extern int ata_sas_async_port_init(struct ata_port *);
+extern void ata_sas_async_probe(struct ata_port *ap);
+extern int ata_sas_sync_probe(struct ata_port *ap);
 extern int ata_sas_port_init(struct ata_port *);
 extern int ata_sas_port_start(struct ata_port *ap);
 extern void ata_sas_port_stop(struct ata_port *ap);
diff --git a/include/scsi/sas_ata.h b/include/scsi/sas_ata.h
index cae55b6..2dfbdaa 100644
--- a/include/scsi/sas_ata.h
+++ b/include/scsi/sas_ata.h
@@ -37,7 +37,7 @@ static inline int dev_is_sata(struct domain_device *dev)
 }
 
 int sas_get_ata_info(struct domain_device *dev, struct ex_phy *phy);
-int sas_ata_init_host_and_port(struct domain_device *found_dev);
+int sas_ata_init(struct domain_device *dev);
 void sas_ata_task_abort(struct sas_task *task);
 void sas_ata_strategy_handler(struct Scsi_Host *shost);
 void sas_ata_eh(struct Scsi_Host *shost, struct list_head *work_q,
@@ -53,7 +53,7 @@ static inline int dev_is_sata(struct domain_device *dev)
 {
 	return 0;
 }
-static inline int sas_ata_init_host_and_port(struct domain_device *found_dev)
+static inline int sas_ata_init(struct domain_device *dev)
 {
 	return 0;
 }