[PATCH] USB: Remove USB private semaphore
This patch (as605) removes the private udev->serialize semaphore,
relying instead on the locking provided by the embedded struct device's
semaphore. The changes are confined to the core, except that the
usb_trylock_device routine now uses the return convention of
down_trylock rather than down_read_trylock (they return opposite values
for no good reason).
A couple of other associated changes are included as well:
Now that we aren't concerned about HCDs that avoid using the
hcd glue layer, usb_disconnect no longer needs to acquire the
usb_bus_lock -- that can be done by usb_remove_hcd where it
belongs.
Devices aren't locked over the same scope of code in
usb_new_device and hub_port_connect_change as they used to be.
This shouldn't cause any trouble.
Along with the preceding driver core patch, this needs a lot of testing.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 40c6c50..dd3bcfb 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -32,7 +32,7 @@
#include "hub.h"
/* Protect struct usb_device->state and ->children members
- * Note: Both are also protected by ->serialize, except that ->state can
+ * Note: Both are also protected by ->dev.sem, except that ->state can
* change to USB_STATE_NOTATTACHED even when the semaphore isn't held. */
static DEFINE_SPINLOCK(device_state_lock);
@@ -975,8 +975,8 @@
/* when everyone grabs locks top->bottom,
* non-overlapping work may be concurrent
*/
- down(&udev->serialize);
- up(&hdev->serialize);
+ usb_lock_device(udev);
+ usb_unlock_device(hdev);
return t + 1;
}
}
@@ -1132,16 +1132,10 @@
* this quiesces everyting except pending urbs.
*/
usb_set_device_state(udev, USB_STATE_NOTATTACHED);
-
- /* lock the bus list on behalf of HCDs unregistering their root hubs */
- if (!udev->parent) {
- down(&usb_bus_list_lock);
- usb_lock_device(udev);
- } else
- down(&udev->serialize);
-
dev_info (&udev->dev, "USB disconnect, address %d\n", udev->devnum);
+ usb_lock_device(udev);
+
/* Free up all the children before we remove this device */
for (i = 0; i < USB_MAXCHILDREN; i++) {
if (udev->children[i])
@@ -1169,11 +1163,7 @@
*pdev = NULL;
spin_unlock_irq(&device_state_lock);
- if (!udev->parent) {
- usb_unlock_device(udev);
- up(&usb_bus_list_lock);
- } else
- up(&udev->serialize);
+ usb_unlock_device(udev);
device_unregister(&udev->dev);
}
@@ -1243,8 +1233,8 @@
*
* This is called with devices which have been enumerated, but not yet
* configured. The device descriptor is available, but not descriptors
- * for any device configuration. The caller must have locked udev and
- * either the parent hub (if udev is a normal device) or else the
+ * for any device configuration. The caller must have locked either
+ * the parent hub (if udev is a normal device) or else the
* usb_bus_list_lock (if udev is a root hub). The parent's pointer to
* udev has already been installed, but udev is not yet visible through
* sysfs or other filesystem code.
@@ -1254,8 +1244,7 @@
*
* This call is synchronous, and may not be used in an interrupt context.
*
- * Only the hub driver should ever call this; root hub registration
- * uses it indirectly.
+ * Only the hub driver or root-hub registrar should ever call this.
*/
int usb_new_device(struct usb_device *udev)
{
@@ -1364,6 +1353,8 @@
}
usb_create_sysfs_dev_files (udev);
+ usb_lock_device(udev);
+
/* choose and set the configuration. that registers the interfaces
* with the driver core, and lets usb device drivers bind to them.
*/
@@ -1385,6 +1376,8 @@
/* USB device state == configured ... usable */
usb_notify_add_device(udev);
+ usb_unlock_device(udev);
+
return 0;
fail:
@@ -1872,11 +1865,8 @@
usb_unlock_device(udev);
/* rebind drivers that had no suspend() */
- if (status == 0) {
- usb_lock_all_devices();
+ if (status == 0)
bus_rescan_devices(&usb_bus_type);
- usb_unlock_all_devices();
- }
return status;
}
@@ -1889,14 +1879,14 @@
/* don't repeat RESUME sequence if this device
* was already woken up by some other task
*/
- down(&udev->serialize);
+ usb_lock_device(udev);
if (udev->state == USB_STATE_SUSPENDED) {
dev_dbg(&udev->dev, "RESUME (wakeup)\n");
/* TRSMRCY = 10 msec */
msleep(10);
status = finish_device_resume(udev);
}
- up(&udev->serialize);
+ usb_unlock_device(udev);
#endif
return status;
}
@@ -1997,7 +1987,7 @@
if (!udev || status < 0)
continue;
- down (&udev->serialize);
+ usb_lock_device(udev);
if (portstat & USB_PORT_STAT_SUSPEND)
status = hub_port_resume(hub, port1, udev);
else {
@@ -2008,7 +1998,7 @@
hub_port_logical_disconnect(hub, port1);
}
}
- up(&udev->serialize);
+ usb_unlock_device(udev);
}
}
#endif
@@ -2573,7 +2563,6 @@
* udev becomes globally accessible, although presumably
* no one will look at it until hdev is unlocked.
*/
- down (&udev->serialize);
status = 0;
/* We mustn't add new devices if the parent hub has
@@ -2597,7 +2586,6 @@
}
}
- up (&udev->serialize);
if (status)
goto loop_disable;