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 (file)
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -2458,11 +2458,13 @@ struct usb_hcd *usb_create_shared_hcd(const struct hc_driver *driver,
                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 @@ EXPORT_SYMBOL_GPL(usb_create_hcd);
  * 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 @@ static int usb_hcd_request_irqs(struct usb_hcd *hcd,
        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 @@ int usb_add_hcd(struct usb_hcd *hcd,
                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_hcd_driver_start:
 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 @@ void usb_remove_hcd(struct usb_hcd *hcd)
                        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 @@ void usb_remove_hcd(struct usb_hcd *hcd)
                usb_put_phy(hcd->phy);
                hcd->phy = NULL;
        }
+
+       usb_put_invalidate_rhdev(hcd);
 }
 EXPORT_SYMBOL_GPL(usb_remove_hcd);
 

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 2912925..5a909ba 100644 (file)
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -55,6 +55,9 @@ static DECLARE_WAIT_QUEUE_HEAD(khubd_wait);
 
 static struct task_struct *khubd_task;
 
+/* synchronize hub-port add/remove and peering operations */
+DEFINE_MUTEX(usb_port_peer_mutex);
+
 /* cycle leds on hubs that aren't blinking for attention */
 static bool blinkenlights = 0;
 module_param (blinkenlights, bool, S_IRUGO);
@@ -1323,6 +1326,7 @@ static int hub_configure(struct usb_hub *hub,
        char *message = "out of memory";
        unsigned unit_load;
        unsigned full_load;
+       unsigned maxchild;
 
        hub->buffer = kmalloc(sizeof(*hub->buffer), GFP_KERNEL);
        if (!hub->buffer) {
@@ -1361,12 +1365,11 @@ static int hub_configure(struct usb_hub *hub,
                goto fail;
        }
 
-       hdev->maxchild = hub->descriptor->bNbrPorts;
-       dev_info (hub_dev, "%d port%s detected\n", hdev->maxchild,
-               (hdev->maxchild == 1) ? "" : "s");
+       maxchild = hub->descriptor->bNbrPorts;
+       dev_info(hub_dev, "%d port%s detected\n", maxchild,
+                       (maxchild == 1) ? "" : "s");
 
-       hub->ports = kzalloc(hdev->maxchild * sizeof(struct usb_port *),
-                            GFP_KERNEL);
+       hub->ports = kzalloc(maxchild * sizeof(struct usb_port *), GFP_KERNEL);
        if (!hub->ports) {
                ret = -ENOMEM;
                goto fail;
@@ -1387,11 +1390,11 @@ static int hub_configure(struct usb_hub *hub,
                int     i;
                char    portstr[USB_MAXCHILDREN + 1];
 
-               for (i = 0; i < hdev->maxchild; i++)
+               for (i = 0; i < maxchild; i++)
                        portstr[i] = hub->descriptor->u.hs.DeviceRemovable
                                    [((i + 1) / 8)] & (1 << ((i + 1) % 8))
                                ? 'F' : 'R';
-               portstr[hdev->maxchild] = 0;
+               portstr[maxchild] = 0;
                dev_dbg(hub_dev, "compound device; port removable status: %s\n", portstr);
        } else
                dev_dbg(hub_dev, "standalone hub\n");
@@ -1503,7 +1506,7 @@ static int hub_configure(struct usb_hub *hub,
                if (hcd->power_budget > 0)
                        hdev->bus_mA = hcd->power_budget;
                else
-                       hdev->bus_mA = full_load * hdev->maxchild;
+                       hdev->bus_mA = full_load * maxchild;
                if (hdev->bus_mA >= full_load)
                        hub->mA_per_port = full_load;
                else {
@@ -1518,7 +1521,7 @@ static int hub_configure(struct usb_hub *hub,
                        hub->descriptor->bHubContrCurrent);
                hub->limited_power = 1;
 
-               if (remaining < hdev->maxchild * unit_load)
+               if (remaining < maxchild * unit_load)
                        dev_warn(hub_dev,
                                        "insufficient power available "
                                        "to use all downstream ports\n");
@@ -1586,15 +1589,19 @@ static int hub_configure(struct usb_hub *hub,
        if (hub->has_indicators && blinkenlights)
                hub->indicator[0] = INDICATOR_CYCLE;
 
-       for (i = 0; i < hdev->maxchild; i++) {
+       mutex_lock(&usb_port_peer_mutex);
+       for (i = 0; i < maxchild; i++) {
                ret = usb_hub_create_port_device(hub, i + 1);
                if (ret < 0) {
                        dev_err(hub->intfdev,
                                "couldn't create port%d device.\n", i + 1);
-                       hdev->maxchild = i;
-                       goto fail_keep_maxchild;
+                       break;
                }
        }
+       hdev->maxchild = i;
+       mutex_unlock(&usb_port_peer_mutex);
+       if (ret < 0)
+               goto fail;
 
        usb_hub_adjust_deviceremovable(hdev, hub->descriptor);
 
@@ -1602,8 +1609,6 @@ static int hub_configure(struct usb_hub *hub,
        return 0;
 
 fail:
-       hdev->maxchild = 0;
-fail_keep_maxchild:
        dev_err (hub_dev, "config failed, %s (err %d)\n",
                        message, ret);
        /* hub_disconnect() frees urb and descriptor */
@@ -1639,6 +1644,8 @@ static void hub_disconnect(struct usb_interface *intf)
        hub->error = 0;
        hub_quiesce(hub, HUB_DISCONNECT);
 
+       mutex_lock(&usb_port_peer_mutex);
+
        /* Avoid races with recursively_mark_NOTATTACHED() */
        spin_lock_irq(&device_state_lock);
        port1 = hdev->maxchild;
@@ -1649,6 +1656,8 @@ static void hub_disconnect(struct usb_interface *intf)
        for (; port1 > 0; --port1)
                usb_hub_remove_port_device(hub, port1);
 
+       mutex_unlock(&usb_port_peer_mutex);
+
        if (hub->hdev->speed == USB_SPEED_HIGH)
                highspeed_hubs--;
 
@@ -4608,6 +4617,8 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1,
                 */
                status = 0;
 
+               mutex_lock(&usb_port_peer_mutex);
+
                /* We mustn't add new devices if the parent hub has
                 * been disconnected; we would race with the
                 * recursively_mark_NOTATTACHED() routine.
@@ -4618,14 +4629,17 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1,
                else
                        port_dev->child = udev;
                spin_unlock_irq(&device_state_lock);
+               mutex_unlock(&usb_port_peer_mutex);
 
                /* Run it through the hoops (find a driver, etc) */
                if (!status) {
                        status = usb_new_device(udev);
                        if (status) {
+                               mutex_lock(&usb_port_peer_mutex);
                                spin_lock_irq(&device_state_lock);
                                port_dev->child = NULL;
                                spin_unlock_irq(&device_state_lock);
+                               mutex_unlock(&usb_port_peer_mutex);
                        }
                }
 

diff --cc drivers/usb/core/hub.h
Simple merge

diff --cc drivers/usb/core/port.c
Simple merge

diff --cc drivers/usb/core/usb.h
Simple merge