usb: assign default peer ports for root hubs
Assume that the peer of a superspeed port is the port with the same id
on the shared_hcd root hub. This identification scheme is required of
external hubs by the USB3 spec [1]. However, for root hubs, tier mismatch
may be in effect [2]. Tier mismatch can only be enumerated via platform
firmware. For now, simply perform the nominal association.
A new lock 'usb_port_peer_mutex' is introduced to synchronize port
device add/remove with peer lookups. It protects peering against
changes to hcd->shared_hcd, hcd->self.root_hub, hdev->maxchild, and
port_dev->child pointers.
[1]: usb 3.1 section 10.3.3
[2]: xhci 1.1 appendix D
Cc: Alan Stern <stern@rowland.harvard.edu>
[alan: usb_port_peer_mutex locking scheme]
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 174eb85..b814075 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -2458,11 +2458,13 @@
mutex_init(hcd->bandwidth_mutex);
dev_set_drvdata(dev, hcd);
} else {
+ mutex_lock(&usb_port_peer_mutex);
hcd->bandwidth_mutex = primary_hcd->bandwidth_mutex;
hcd->primary_hcd = primary_hcd;
primary_hcd->primary_hcd = primary_hcd;
hcd->shared_hcd = primary_hcd;
primary_hcd->shared_hcd = hcd;
+ mutex_unlock(&usb_port_peer_mutex);
}
kref_init(&hcd->kref);
@@ -2514,18 +2516,25 @@
* deallocated.
*
* Make sure to only deallocate the bandwidth_mutex when the primary HCD is
- * freed. When hcd_release() is called for the non-primary HCD, set the
- * primary_hcd's shared_hcd pointer to null (since the non-primary HCD will be
- * freed shortly).
+ * freed. When hcd_release() is called for either hcd in a peer set
+ * invalidate the peer's ->shared_hcd and ->primary_hcd pointers to
+ * block new peering attempts
*/
-static void hcd_release (struct kref *kref)
+static void hcd_release(struct kref *kref)
{
struct usb_hcd *hcd = container_of (kref, struct usb_hcd, kref);
+ mutex_lock(&usb_port_peer_mutex);
if (usb_hcd_is_primary_hcd(hcd))
kfree(hcd->bandwidth_mutex);
- else
- hcd->shared_hcd->shared_hcd = NULL;
+ if (hcd->shared_hcd) {
+ struct usb_hcd *peer = hcd->shared_hcd;
+
+ peer->shared_hcd = NULL;
+ if (peer->primary_hcd == hcd)
+ peer->primary_hcd = NULL;
+ }
+ mutex_unlock(&usb_port_peer_mutex);
kfree(hcd);
}
@@ -2593,6 +2602,21 @@
return 0;
}
+/*
+ * Before we free this root hub, flush in-flight peering attempts
+ * and disable peer lookups
+ */
+static void usb_put_invalidate_rhdev(struct usb_hcd *hcd)
+{
+ struct usb_device *rhdev;
+
+ mutex_lock(&usb_port_peer_mutex);
+ rhdev = hcd->self.root_hub;
+ hcd->self.root_hub = NULL;
+ mutex_unlock(&usb_port_peer_mutex);
+ usb_put_dev(rhdev);
+}
+
/**
* usb_add_hcd - finish generic HCD structure initialization and register
* @hcd: the usb_hcd structure to initialize
@@ -2653,7 +2677,9 @@
retval = -ENOMEM;
goto err_allocate_root_hub;
}
+ mutex_lock(&usb_port_peer_mutex);
hcd->self.root_hub = rhdev;
+ mutex_unlock(&usb_port_peer_mutex);
switch (hcd->speed) {
case HCD_USB11:
@@ -2762,7 +2788,7 @@
err_request_irq:
err_hcd_driver_setup:
err_set_rh_speed:
- usb_put_dev(hcd->self.root_hub);
+ usb_put_invalidate_rhdev(hcd);
err_allocate_root_hub:
usb_deregister_bus(&hcd->self);
err_register_bus:
@@ -2842,7 +2868,6 @@
free_irq(hcd->irq, hcd);
}
- usb_put_dev(hcd->self.root_hub);
usb_deregister_bus(&hcd->self);
hcd_buffer_destroy(hcd);
if (hcd->remove_phy && hcd->phy) {
@@ -2850,6 +2875,8 @@
usb_put_phy(hcd->phy);
hcd->phy = NULL;
}
+
+ usb_put_invalidate_rhdev(hcd);
}
EXPORT_SYMBOL_GPL(usb_remove_hcd);