[SCSI] libsas: unify domain_device sas_rphy lifetimes

Since the domain_device can out live the scsi_target we need the rphy to
follow suit otherwise we run into issues like:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000050
IP: [<ffffffffa011561b>] sas_ata_printk+0x43/0x6f [libsas]
PGD 0
Oops: 0000 [#1] SMP
CPU 1
Modules linked in: ses enclosure isci libsas scsi_transport_sas fuse sunrpc cpufreq_ondemand acpi_cpufreq freq_table mperf microcode pcspkr igb joydev iTCO_wdt ioatdma iTCO_vendor_support i2c_i801 i2c_core dca wmi hed ipv6 pata_acpi ata_generic [last unloaded: scsi_wait_scan]

Pid: 129, comm: kworker/u:3 Not tainted 3.3.0-rc5-isci+ #1 Intel Corporation SandyBridge Platform/To be filled by O.E.M.
RIP: 0010:[<ffffffffa011561b>] [<ffffffffa011561b>] sas_ata_printk+0x43/0x6f [libsas]
RSP: 0018:ffff88042232dd70 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff8804283165b8 RCX: ffff88042232dda0
RDX: ffff88042232dd78 RSI: ffff8804283165b8 RDI: ffffffffa01188d7
RBP: ffff88042232ddd0 R08: ffff880388454000 R09: ffff8803edfde1f8
R10: ffff8803edfde1f8 R11: ffff8803edfde1f8 R12: ffff880428316750
R13: ffff880388454000 R14: ffff8803f88b31d0 R15: ffff8803f8b21d50
FS: 0000000000000000(0000) GS:ffff88042ee20000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 0000000000000050 CR3: 0000000001a05000 CR4: 00000000000406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process kworker/u:3 (pid: 129, threadinfo ffff88042232c000, task ffff88042230c920)
Stack:
0000000000000000 ffff880400000018 ffff88042232dde0 ffff88042232dda0
ffffffffa01188c4 ffff88042ee93af0 ffff88042232ddb0 ffffffff8100e047
ffff88042232de10 ffff880420e5a2c8 ffff8803f8b21d50 ffff8803edfde1f8
Call Trace:
[<ffffffff8100e047>] ? load_TLS+0xb/0xf
[<ffffffffa01156ad>] async_sas_ata_eh+0x66/0x95 [libsas]
[<ffffffff810655e1>] async_run_entry_fn+0x9e/0x131

Reported-by: Tom Jackson <[e-mail]>
Tested-by: Tom Jackson <[e-mail]>
Signed-off-by: Dan Williams <[e-mail]>
Signed-off-by: James Bottomley <[e-mail]>

drivers/scsi/libsas/sas_discover.c

···
 	sas_device_set_phy(dev, port->port);
 
 	dev->rphy = rphy;
+	get_device(&dev->rphy->dev);
 
 	if (dev_is_sata(dev) || dev->dev_type == SAS_END_DEV)
 		list_add_tail(&dev->disco_list_node, &port->disco_list);
···
 {
 	struct domain_device *dev = container_of(kref, typeof(*dev), kref);
 
+	put_device(&dev->rphy->dev);
+	dev->rphy = NULL;
+
 	if (dev->parent)
 		sas_put_device(dev->parent);
 
···
 
 		sas_remove_children(&dev->rphy->dev);
 		sas_rphy_delete(dev->rphy);
-		dev->rphy = NULL;
 		sas_unregister_common_dev(port, dev);
 	}
 }
···
 		/* this rphy never saw sas_rphy_add */
 		list_del_init(&dev->disco_list_node);
 		sas_rphy_free(dev->rphy);
-		dev->rphy = NULL;
 		sas_unregister_common_dev(port, dev);
+		return;
 	}
 
-	if (dev->rphy && !test_and_set_bit(SAS_DEV_DESTROY, &dev->state)) {
+	if (!test_and_set_bit(SAS_DEV_DESTROY, &dev->state)) {
 		sas_rphy_unlink(dev->rphy);
 		list_move_tail(&dev->disco_list_node, &port->destroy_list);
 		sas_discover_event(dev->port, DISCE_DESTRUCT);
···
 
 	if (error) {
 		sas_rphy_free(dev->rphy);
-		dev->rphy = NULL;
-
 		list_del_init(&dev->disco_list_node);
 		spin_lock_irq(&port->dev_list_lock);
 		list_del_init(&dev->dev_list_node);

drivers/scsi/libsas/sas_expander.c

···
 		sas_init_dev(child);
 
 		child->rphy = rphy;
+		get_device(&rphy->dev);
 
 		list_add_tail(&child->disco_list_node, &parent->port->disco_list);
 
···
 		sas_init_dev(child);
 
 		child->rphy = rphy;
+		get_device(&rphy->dev);
 		sas_fill_in_rphy(child, rphy);
 
 		list_add_tail(&child->disco_list_node, &parent->port->disco_list);
···
 
  out_list_del:
 	sas_rphy_free(child->rphy);
-	child->rphy = NULL;
-
 	list_del(&child->disco_list_node);
 	spin_lock_irq(&parent->port->dev_list_lock);
 	list_del(&child->dev_list_node);
···
 	}
 	port = parent->port;
 	child->rphy = rphy;
+	get_device(&rphy->dev);
 	edev = rphy_to_expander_device(rphy);
 	child->dev_type = phy->attached_dev_type;
 	kref_get(&parent->kref);
···
 
 	res = sas_discover_expander(child);
 	if (res) {
+		sas_rphy_delete(rphy);
 		spin_lock_irq(&parent->port->dev_list_lock);
 		list_del(&child->dev_list_node);
 		spin_unlock_irq(&parent->port->dev_list_lock);