USB: separate usb_address0 mutexes for each bus

This patch creates a separate instance of the usb_address0 mutex for each USB
bus, and attaches it to the usb_bus device struct. This allows devices on
separate buses to be enumerated in parallel; saving time.

In the current code, there is a single, global instance of the usb_address0
mutex which is used for all devices on all buses. This isn't completely
necessary, as this mutex is only needed to prevent address0 collisions for
devices on the *same* bus (usb 2.0 spec, sec 4.6.1). This superfluous coverage
can cause additional delay in system resume on systems with multiple hosts
(up to several seconds depending on what devices are attached).

Signed-off-by: Todd Brandt <todd.e.brandt@linux.intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index adddc66c9e8db1f66ad10ce45613c73d89479481..174eb857a6b45b85109c3321196685e1114b876f 100644 (file)
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -918,6 +918,7 @@ static void usb_bus_init (struct usb_bus *bus)
        bus->bandwidth_allocated = 0;
        bus->bandwidth_int_reqs  = 0;
        bus->bandwidth_isoc_reqs = 0;
+       mutex_init(&bus->usb_address0_mutex);
 
        INIT_LIST_HEAD (&bus->bus_list);
 }

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 090469ebfcfff3a1fb686c4adbf0817bc1b27f22..726fa072c3fe3ddc1566f7b8ef0a3d4fa32714bc 100644 (file)
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -4016,8 +4016,6 @@ static int
 hub_port_init (struct usb_hub *hub, struct usb_device *udev, int port1,
                int retry_counter)
 {
-       static DEFINE_MUTEX(usb_address0_mutex);
-
        struct usb_device       *hdev = hub->hdev;
        struct usb_hcd          *hcd = bus_to_hcd(hdev->bus);
        int                     i, j, retval;
@@ -4040,7 +4038,7 @@ hub_port_init (struct usb_hub *hub, struct usb_device *udev, int port1,
        if (oldspeed == USB_SPEED_LOW)
                delay = HUB_LONG_RESET_TIME;
 
-       mutex_lock(&usb_address0_mutex);
+       mutex_lock(&hdev->bus->usb_address0_mutex);
 
        /* Reset the device; full speed may morph to high speed */
        /* FIXME a USB 2.0 device may morph into SuperSpeed on reset. */
@@ -4317,7 +4315,7 @@ fail:
                hub_port_disable(hub, port1, 0);
                update_devnum(udev, devnum);    /* for disconnect processing */
        }
-       mutex_unlock(&usb_address0_mutex);
+       mutex_unlock(&hdev->bus->usb_address0_mutex);
        return retval;
 }
 

diff --git a/include/linux/usb.h b/include/linux/usb.h
index 6b7ec376fb4d98baa5ec5a8fa33fd2d83b06343e..d2465bc0e73c211011af86b1b05d74baa5ae2ab6 100644 (file)
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -352,6 +352,8 @@ struct usb_bus {
        struct usb_bus *hs_companion;   /* Companion EHCI bus, if any */
        struct list_head bus_list;      /* list of busses */
 
+       struct mutex usb_address0_mutex; /* unaddressed device mutex */
+
        int bandwidth_allocated;        /* on this bus: how much of the time
                                         * reserved for periodic (intr/iso)
                                         * requests is used, on average?