On Fri, 27 Feb 2004, Greg KH wrote:
> On Wed, Feb 25, 2004 at 10:05:37AM -0500, Alan Stern wrote:
>
> > Why would anyone want to do this, you ask? Well the USB subsystem does it
> > already. Each USB device can have several configurations, only one of
> > which is active at any time. Corresponding to each configuration is a set
> > of struct devices, and they (together with their embedded kobjects) are
> > allocated and initialized when the USB device is first detected. The
> > struct devices are add()'ed and del()'ed as configurations are activated
> > and deactivated, leading to just the sort of call sequence shown above.
>
> Then we need to fix this.
The driver model does not support repeated device_add(), device_del(),
device_add(), device_del(), ... calls for the same device. But that's
what happens to an interface's embedded struct device when we change
configurations.
Accordingly, this patch changes the device_add()/device_del() calls for
interfaces to device_register()/device_unregister(). When the interface
is unregistered the new code waits for the release method to run, so that
it will be safe to re-register the interface should the former
configuration be reinstated.
Greg, please check this out to make sure I haven't made some dumb mistake.
It works on my system and it fixes a memory leak in the USB system.
Alan Stern
===== include/linux/usb.h 1.171 vs edited =====
--- 1.171/include/linux/usb.h Tue Feb 10 00:33:16 2004
+++ edited/include/linux/usb.h Fri Feb 27 16:46:19 2004
@@ -89,6 +89,8 @@
* number from the USB core by calling usb_register_dev().
* @dev: driver model's view of this device
* @class_dev: driver model's class view of this device.
+ * @released: wait for the interface to be released when changing
+ * configurations.
*
* USB device drivers attach to interfaces on a physical device. Each
* interface encapsulates a single high level function, such as feeding
@@ -122,6 +124,7 @@
int minor; /* minor number this interface is bound to */
struct device dev; /* interface specific device info */
struct class_device *class_dev;
+ struct completion *released; /* wait for release */
};
#define to_usb_interface(d) container_of(d, struct usb_interface, dev)
#define interface_to_usbdev(intf) \
===== drivers/usb/core/config.c 1.28 vs edited =====
--- 1.28/drivers/usb/core/config.c Fri Sep 26 12:37:44 2003
+++ edited/drivers/usb/core/config.c Fri Feb 27 16:46:19 2004
@@ -72,13 +72,10 @@
return buffer - buffer0;
}
-static void usb_release_intf(struct device *dev)
+static void usb_free_intf(struct usb_interface *intf)
{
- struct usb_interface *intf;
int j;
- intf = to_usb_interface(dev);
-
if (intf->altsetting) {
for (j = 0; j < intf->num_altsetting; j++) {
struct usb_host_interface *as = &intf->altsetting[j];
@@ -235,8 +232,6 @@
return -ENOMEM;
}
memset(interface, 0, sizeof(struct usb_interface));
- interface->dev.release = usb_release_intf;
- device_initialize(&interface->dev);
}
/* Go through the descriptors, checking their length and counting the
@@ -374,7 +369,7 @@
struct usb_interface *ifp = cf->interface[i];
if (ifp)
- put_device(&ifp->dev);
+ usb_free_intf(ifp);
}
}
kfree(dev->config);
===== drivers/usb/core/message.c 1.69 vs edited =====
--- 1.69/drivers/usb/core/message.c Fri Feb 27 13:09:15 2004
+++ edited/drivers/usb/core/message.c Fri Feb 27 16:46:19 2004
@@ -793,6 +793,13 @@
}
}
+static void release_interface(struct device *dev)
+{
+ struct usb_interface *interface = to_usb_interface(dev);
+
+ complete(interface->released);
+}
+
/*
* usb_disable_device - Disable all the endpoints for a USB device
* @dev: the device whose endpoints are being disabled
@@ -822,12 +829,16 @@
if (dev->actconfig) {
for (i = 0; i < dev->actconfig->desc.bNumInterfaces; i++) {
struct usb_interface *interface;
+ struct completion intf_completion;
/* remove this interface */
interface = dev->actconfig->interface[i];
dev_dbg (&dev->dev, "unregistering interface %s\n",
interface->dev.bus_id);
- device_del(&interface->dev);
+ init_completion (&intf_completion);
+ interface->released = &intf_completion;
+ device_unregister (&interface->dev);
+ wait_for_completion (&intf_completion);
}
dev->actconfig = 0;
if (dev->state == USB_STATE_CONFIGURED)
@@ -1145,6 +1156,7 @@
intf->dev.driver = NULL;
intf->dev.bus = &usb_bus_type;
intf->dev.dma_mask = dev->dev.dma_mask;
+ intf->dev.release = release_interface;
sprintf (&intf->dev.bus_id[0], "%d-%s:%d.%d",
dev->bus->busnum, dev->devpath,
configuration,
@@ -1153,7 +1165,7 @@
"registering %s (config #%d, interface %d)\n",
intf->dev.bus_id, configuration,
desc->bInterfaceNumber);
- device_add (&intf->dev);
+ device_register (&intf->dev);
usb_create_driverfs_intf_files (intf);
}
}
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