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[PATCH] USB: Remove USB private semaphore

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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>
This commit is contained in:
Alan Stern
2005-11-17 17:10:32 -05:00
committed by Greg Kroah-Hartman
parent 75318d2d7c
commit 9ad3d6ccf5
9 changed files with 37 additions and 154 deletions
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48
drivers/usb/core/hub.c
View File

@@ -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 @@ static int locktree(struct usb_device *udev)
/* 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 @@ void usb_disconnect(struct usb_device **pdev)
* 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 @@ void usb_disconnect(struct usb_device **pdev)
*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 @@ static inline void show_string(struct usb_device *udev, char *id, char *string)
*
* 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 @@ static inline void show_string(struct usb_device *udev, char *id, char *string)
*
* 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 @@ int usb_new_device(struct usb_device *udev)
}
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 @@ int usb_new_device(struct usb_device *udev)
/* USB device state == configured ... usable */
usb_notify_add_device(udev);
usb_unlock_device(udev);
return 0;
fail:
@@ -1872,11 +1865,8 @@ int usb_resume_device(struct usb_device *udev)
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 @@ static int remote_wakeup(struct usb_device *udev)
/* 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 @@ static int hub_resume(struct usb_interface *intf)
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 @@ static int hub_resume(struct usb_interface *intf)
hub_port_logical_disconnect(hub, port1);
}
}
up(&udev->serialize);
usb_unlock_device(udev);
}
}
#endif
@@ -2573,7 +2563,6 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1,
* 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 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1,
}
}
up (&udev->serialize);
if (status)
goto loop_disable;