forked from Minki/linux
[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>
This commit is contained in:
parent
75318d2d7c
commit
9ad3d6ccf5
@ -545,10 +545,10 @@ static ssize_t usb_device_dump(char __user **buffer, size_t *nbytes, loff_t *ski
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struct usb_device *childdev = usbdev->children[chix];
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if (childdev) {
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down(&childdev->serialize);
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usb_lock_device(childdev);
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ret = usb_device_dump(buffer, nbytes, skip_bytes, file_offset, childdev,
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bus, level + 1, chix, ++cnt);
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up(&childdev->serialize);
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usb_unlock_device(childdev);
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if (ret == -EFAULT)
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return total_written;
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total_written += ret;
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@ -1349,9 +1349,7 @@ static int proc_ioctl(struct dev_state *ps, struct usbdevfs_ioctl *ctl)
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/* let kernel drivers try to (re)bind to the interface */
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case USBDEVFS_CONNECT:
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usb_unlock_device(ps->dev);
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usb_lock_all_devices();
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bus_rescan_devices(intf->dev.bus);
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usb_unlock_all_devices();
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usb_lock_device(ps->dev);
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break;
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@ -432,9 +432,7 @@ int usb_register_driver(struct usb_driver *new_driver, struct module *owner)
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spin_lock_init(&new_driver->dynids.lock);
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INIT_LIST_HEAD(&new_driver->dynids.list);
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usb_lock_all_devices();
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retval = driver_register(&new_driver->driver);
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usb_unlock_all_devices();
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if (!retval) {
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pr_info("%s: registered new driver %s\n",
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@ -465,11 +463,9 @@ void usb_deregister(struct usb_driver *driver)
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{
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pr_info("%s: deregistering driver %s\n", usbcore_name, driver->name);
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usb_lock_all_devices();
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usb_remove_newid_file(driver);
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usb_free_dynids(driver);
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driver_unregister(&driver->driver);
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usb_unlock_all_devices();
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usbfs_update_special();
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}
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@ -857,9 +857,7 @@ static int register_root_hub (struct usb_device *usb_dev,
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return (retval < 0) ? retval : -EMSGSIZE;
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}
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usb_lock_device (usb_dev);
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retval = usb_new_device (usb_dev);
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usb_unlock_device (usb_dev);
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if (retval) {
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usb_dev->bus->root_hub = NULL;
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dev_err (parent_dev, "can't register root hub for %s, %d\n",
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@ -1891,7 +1889,10 @@ void usb_remove_hcd(struct usb_hcd *hcd)
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spin_lock_irq (&hcd_root_hub_lock);
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hcd->rh_registered = 0;
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spin_unlock_irq (&hcd_root_hub_lock);
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down(&usb_bus_list_lock);
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usb_disconnect(&hcd->self.root_hub);
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up(&usb_bus_list_lock);
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hcd->poll_rh = 0;
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del_timer_sync(&hcd->rh_timer);
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@ -32,7 +32,7 @@
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#include "hub.h"
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/* Protect struct usb_device->state and ->children members
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* Note: Both are also protected by ->serialize, except that ->state can
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* Note: Both are also protected by ->dev.sem, except that ->state can
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* change to USB_STATE_NOTATTACHED even when the semaphore isn't held. */
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static DEFINE_SPINLOCK(device_state_lock);
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@ -975,8 +975,8 @@ static int locktree(struct usb_device *udev)
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/* when everyone grabs locks top->bottom,
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* non-overlapping work may be concurrent
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*/
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down(&udev->serialize);
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up(&hdev->serialize);
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usb_lock_device(udev);
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usb_unlock_device(hdev);
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return t + 1;
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}
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}
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@ -1132,16 +1132,10 @@ void usb_disconnect(struct usb_device **pdev)
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* this quiesces everyting except pending urbs.
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*/
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usb_set_device_state(udev, USB_STATE_NOTATTACHED);
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/* lock the bus list on behalf of HCDs unregistering their root hubs */
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if (!udev->parent) {
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down(&usb_bus_list_lock);
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usb_lock_device(udev);
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} else
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down(&udev->serialize);
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dev_info (&udev->dev, "USB disconnect, address %d\n", udev->devnum);
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usb_lock_device(udev);
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/* Free up all the children before we remove this device */
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for (i = 0; i < USB_MAXCHILDREN; i++) {
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if (udev->children[i])
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@ -1169,11 +1163,7 @@ void usb_disconnect(struct usb_device **pdev)
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*pdev = NULL;
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spin_unlock_irq(&device_state_lock);
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if (!udev->parent) {
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usb_unlock_device(udev);
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up(&usb_bus_list_lock);
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} else
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up(&udev->serialize);
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device_unregister(&udev->dev);
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}
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@ -1243,8 +1233,8 @@ static inline void show_string(struct usb_device *udev, char *id, char *string)
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*
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* This is called with devices which have been enumerated, but not yet
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* configured. The device descriptor is available, but not descriptors
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* for any device configuration. The caller must have locked udev and
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* either the parent hub (if udev is a normal device) or else the
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* for any device configuration. The caller must have locked either
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* the parent hub (if udev is a normal device) or else the
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* usb_bus_list_lock (if udev is a root hub). The parent's pointer to
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* udev has already been installed, but udev is not yet visible through
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* sysfs or other filesystem code.
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@ -1254,8 +1244,7 @@ static inline void show_string(struct usb_device *udev, char *id, char *string)
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*
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* This call is synchronous, and may not be used in an interrupt context.
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*
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* Only the hub driver should ever call this; root hub registration
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* uses it indirectly.
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* Only the hub driver or root-hub registrar should ever call this.
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*/
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int usb_new_device(struct usb_device *udev)
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{
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@ -1364,6 +1353,8 @@ int usb_new_device(struct usb_device *udev)
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}
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usb_create_sysfs_dev_files (udev);
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usb_lock_device(udev);
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/* choose and set the configuration. that registers the interfaces
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* with the driver core, and lets usb device drivers bind to them.
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*/
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@ -1385,6 +1376,8 @@ int usb_new_device(struct usb_device *udev)
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/* USB device state == configured ... usable */
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usb_notify_add_device(udev);
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usb_unlock_device(udev);
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return 0;
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fail:
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@ -1872,11 +1865,8 @@ int usb_resume_device(struct usb_device *udev)
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usb_unlock_device(udev);
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/* rebind drivers that had no suspend() */
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if (status == 0) {
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usb_lock_all_devices();
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if (status == 0)
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bus_rescan_devices(&usb_bus_type);
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usb_unlock_all_devices();
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}
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return status;
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}
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@ -1889,14 +1879,14 @@ static int remote_wakeup(struct usb_device *udev)
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/* don't repeat RESUME sequence if this device
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* was already woken up by some other task
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*/
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down(&udev->serialize);
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usb_lock_device(udev);
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if (udev->state == USB_STATE_SUSPENDED) {
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dev_dbg(&udev->dev, "RESUME (wakeup)\n");
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/* TRSMRCY = 10 msec */
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msleep(10);
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status = finish_device_resume(udev);
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}
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up(&udev->serialize);
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usb_unlock_device(udev);
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#endif
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return status;
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}
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@ -1997,7 +1987,7 @@ static int hub_resume(struct usb_interface *intf)
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if (!udev || status < 0)
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continue;
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down (&udev->serialize);
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usb_lock_device(udev);
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if (portstat & USB_PORT_STAT_SUSPEND)
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status = hub_port_resume(hub, port1, udev);
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else {
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@ -2008,7 +1998,7 @@ static int hub_resume(struct usb_interface *intf)
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hub_port_logical_disconnect(hub, port1);
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}
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}
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up(&udev->serialize);
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usb_unlock_device(udev);
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}
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}
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#endif
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@ -2573,7 +2563,6 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1,
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* udev becomes globally accessible, although presumably
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* no one will look at it until hdev is unlocked.
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*/
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down (&udev->serialize);
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status = 0;
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/* We mustn't add new devices if the parent hub has
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@ -2597,7 +2586,6 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1,
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}
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}
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up (&udev->serialize);
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if (status)
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goto loop_disable;
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@ -32,7 +32,6 @@
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#include <linux/spinlock.h>
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#include <linux/errno.h>
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#include <linux/smp_lock.h>
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#include <linux/rwsem.h>
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#include <linux/usb.h>
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#include <asm/io.h>
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@ -49,8 +48,6 @@ const char *usbcore_name = "usbcore";
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static int nousb; /* Disable USB when built into kernel image */
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/* Not honored on modular build */
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static DECLARE_RWSEM(usb_all_devices_rwsem);
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/**
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* usb_ifnum_to_if - get the interface object with a given interface number
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@ -446,8 +443,6 @@ usb_alloc_dev(struct usb_device *parent, struct usb_bus *bus, unsigned port1)
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dev->parent = parent;
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INIT_LIST_HEAD(&dev->filelist);
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init_MUTEX(&dev->serialize);
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return dev;
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}
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@ -520,75 +515,20 @@ void usb_put_intf(struct usb_interface *intf)
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/* USB device locking
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*
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* Although locking USB devices should be straightforward, it is
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* complicated by the way the driver-model core works. When a new USB
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* driver is registered or unregistered, the core will automatically
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* probe or disconnect all matching interfaces on all USB devices while
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* holding the USB subsystem writelock. There's no good way for us to
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* tell which devices will be used or to lock them beforehand; our only
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* option is to effectively lock all the USB devices.
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*
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* We do that by using a private rw-semaphore, usb_all_devices_rwsem.
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* When locking an individual device you must first acquire the rwsem's
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* readlock. When a driver is registered or unregistered the writelock
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* must be held. These actions are encapsulated in the subroutines
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* below, so all a driver needs to do is call usb_lock_device() and
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* usb_unlock_device().
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* USB devices and interfaces are locked using the semaphore in their
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* embedded struct device. The hub driver guarantees that whenever a
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* device is connected or disconnected, drivers are called with the
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* USB device locked as well as their particular interface.
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*
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* Complications arise when several devices are to be locked at the same
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* time. Only hub-aware drivers that are part of usbcore ever have to
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* do this; nobody else needs to worry about it. The problem is that
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* usb_lock_device() must not be called to lock a second device since it
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* would acquire the rwsem's readlock reentrantly, leading to deadlock if
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* another thread was waiting for the writelock. The solution is simple:
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*
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* When locking more than one device, call usb_lock_device()
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* to lock the first one. Lock the others by calling
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* down(&udev->serialize) directly.
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*
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* When unlocking multiple devices, use up(&udev->serialize)
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* to unlock all but the last one. Unlock the last one by
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* calling usb_unlock_device().
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* do this; nobody else needs to worry about it. The rule for locking
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* is simple:
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*
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* When locking both a device and its parent, always lock the
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* the parent first.
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*/
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/**
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* usb_lock_device - acquire the lock for a usb device structure
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* @udev: device that's being locked
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*
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* Use this routine when you don't hold any other device locks;
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* to acquire nested inner locks call down(&udev->serialize) directly.
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* This is necessary for proper interaction with usb_lock_all_devices().
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*/
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void usb_lock_device(struct usb_device *udev)
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{
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down_read(&usb_all_devices_rwsem);
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down(&udev->serialize);
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}
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/**
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* usb_trylock_device - attempt to acquire the lock for a usb device structure
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* @udev: device that's being locked
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*
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* Don't use this routine if you already hold a device lock;
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* use down_trylock(&udev->serialize) instead.
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* This is necessary for proper interaction with usb_lock_all_devices().
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*
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* Returns 1 if successful, 0 if contention.
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*/
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int usb_trylock_device(struct usb_device *udev)
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{
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if (!down_read_trylock(&usb_all_devices_rwsem))
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return 0;
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if (down_trylock(&udev->serialize)) {
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up_read(&usb_all_devices_rwsem);
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return 0;
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}
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return 1;
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}
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/**
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* usb_lock_device_for_reset - cautiously acquire the lock for a
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* usb device structure
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@ -627,7 +567,7 @@ int usb_lock_device_for_reset(struct usb_device *udev,
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}
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}
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while (!usb_trylock_device(udev)) {
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while (usb_trylock_device(udev) != 0) {
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/* If we can't acquire the lock after waiting one second,
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* we're probably deadlocked */
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@ -645,39 +585,6 @@ int usb_lock_device_for_reset(struct usb_device *udev,
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return 1;
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}
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/**
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* usb_unlock_device - release the lock for a usb device structure
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* @udev: device that's being unlocked
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*
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* Use this routine when releasing the only device lock you hold;
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* to release inner nested locks call up(&udev->serialize) directly.
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* This is necessary for proper interaction with usb_lock_all_devices().
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*/
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void usb_unlock_device(struct usb_device *udev)
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{
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up(&udev->serialize);
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up_read(&usb_all_devices_rwsem);
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}
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/**
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* usb_lock_all_devices - acquire the lock for all usb device structures
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*
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* This is necessary when registering a new driver or probing a bus,
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* since the driver-model core may try to use any usb_device.
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*/
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void usb_lock_all_devices(void)
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{
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down_write(&usb_all_devices_rwsem);
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}
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/**
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* usb_unlock_all_devices - release the lock for all usb device structures
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*/
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void usb_unlock_all_devices(void)
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{
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up_write(&usb_all_devices_rwsem);
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}
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static struct usb_device *match_device(struct usb_device *dev,
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u16 vendor_id, u16 product_id)
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@ -700,10 +607,10 @@ static struct usb_device *match_device(struct usb_device *dev,
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/* look through all of the children of this device */
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for (child = 0; child < dev->maxchild; ++child) {
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if (dev->children[child]) {
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down(&dev->children[child]->serialize);
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usb_lock_device(dev->children[child]);
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ret_dev = match_device(dev->children[child],
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vendor_id, product_id);
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up(&dev->children[child]->serialize);
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usb_unlock_device(dev->children[child]);
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if (ret_dev)
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goto exit;
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}
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@ -1300,10 +1207,7 @@ EXPORT_SYMBOL(usb_put_dev);
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EXPORT_SYMBOL(usb_get_dev);
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EXPORT_SYMBOL(usb_hub_tt_clear_buffer);
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EXPORT_SYMBOL(usb_lock_device);
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EXPORT_SYMBOL(usb_trylock_device);
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EXPORT_SYMBOL(usb_lock_device_for_reset);
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EXPORT_SYMBOL(usb_unlock_device);
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EXPORT_SYMBOL(usb_driver_claim_interface);
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EXPORT_SYMBOL(usb_driver_release_interface);
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|
@ -16,9 +16,6 @@ extern int usb_get_device_descriptor(struct usb_device *dev,
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extern char *usb_cache_string(struct usb_device *udev, int index);
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extern int usb_set_configuration(struct usb_device *dev, int configuration);
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extern void usb_lock_all_devices(void);
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extern void usb_unlock_all_devices(void);
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extern void usb_kick_khubd(struct usb_device *dev);
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extern void usb_suspend_root_hub(struct usb_device *hdev);
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extern void usb_resume_root_hub(struct usb_device *dev);
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|
@ -372,7 +372,7 @@ done:
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& ohci->hc_control)
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== OHCI_USB_OPER
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&& time_after (jiffies, ohci->next_statechange)
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&& usb_trylock_device (hcd->self.root_hub)
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&& usb_trylock_device (hcd->self.root_hub) == 0
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) {
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ohci_vdbg (ohci, "autosuspend\n");
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(void) ohci_bus_suspend (hcd);
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|
@ -329,8 +329,6 @@ struct usb_device {
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struct usb_tt *tt; /* low/full speed dev, highspeed hub */
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int ttport; /* device port on that tt hub */
|
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|
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struct semaphore serialize;
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unsigned int toggle[2]; /* one bit for each endpoint
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* ([0] = IN, [1] = OUT) */
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@ -377,11 +375,12 @@ struct usb_device {
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extern struct usb_device *usb_get_dev(struct usb_device *dev);
|
||||
extern void usb_put_dev(struct usb_device *dev);
|
||||
|
||||
extern void usb_lock_device(struct usb_device *udev);
|
||||
extern int usb_trylock_device(struct usb_device *udev);
|
||||
/* USB device locking */
|
||||
#define usb_lock_device(udev) down(&(udev)->dev.sem)
|
||||
#define usb_unlock_device(udev) up(&(udev)->dev.sem)
|
||||
#define usb_trylock_device(udev) down_trylock(&(udev)->dev.sem)
|
||||
extern int usb_lock_device_for_reset(struct usb_device *udev,
|
||||
struct usb_interface *iface);
|
||||
extern void usb_unlock_device(struct usb_device *udev);
|
||||
|
||||
/* USB port reset for device reinitialization */
|
||||
extern int usb_reset_device(struct usb_device *dev);
|
||||
|
Loading…
Reference in New Issue
Block a user