On Mon, 26 Jan 2004, Greg KH wrote:
> On Mon, Jan 26, 2004 at 04:41:11PM -0500, Alan Stern wrote:
>
> > P.S.: Since device_unregister_wait() is going away, does that mean that
> > struct device ->complete is also going to be removed?
>
> Yup. Don't need to burden all users of struct device with that. Is
> that ok with you?
Yes. I've sent a patch by way of David Brownell to remove some uses of
device_unregister_wait() and dev->complete in the new File Storage
Gadget code.
Below is a revised version of patch as163, which also removes
dev->complete and is meant to apply to a clean kernel (i.e., without
as121b already installed). To summarize the purpose of this patch: When a
new configuration is loaded, instead of calling device_add() for the
embedded struct devices in the new interfaces, it calls
device_register(). Likewise, it unregisters the old interfaces instead of
doing device_del().
This isn't a matter of optimization or redistributing effort; it is
necessary for proper interaction with the driver-model core. So long as
you retain the change from last December whereby a device isn't released
until all its children have been released, any device_add() - device_del()
- device_add() sequence will result in messed-up refcounts. Without this
patch, the current code creates just such a sequence when you change from
one configuration to another and then back. Also it fails ever to
release a struct usb_device, since the children interface devices don't
get released until the usb_device's release() function calls
usb_destroy_configuration().
If that change is ever reverted from the driver-model core, this patch
won't be needed any more.
Alan Stern
===== 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 Mon Jan 26 14:19:25 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);
===== message.c 1.65 vs edited =====
--- 1.65/drivers/usb/core/message.c Tue Dec 30 13:25:12 2003
+++ edited/drivers/usb/core/message.c Mon Jan 26 14:47:23 2004
@@ -775,6 +787,13 @@
}
}
+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
@@ -804,12 +823,16 @@
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)
@@ -1127,6 +1150,7 @@
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,
@@ -1135,7 +1159,7 @@
"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);
}
}
===== include/linux/usb.h 1.166 vs edited =====
--- 1.166/include/linux/usb.h Tue Dec 30 13:25:15 2003
+++ edited/include/linux/usb.h Mon Jan 26 14:49:08 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) \
@@ -210,6 +213,7 @@
struct class_device class_dev; /* class device for this bus */
void (*release)(struct usb_bus *bus); /* function to destroy this bus's
memory */
+ struct completion *released; /* wait for release */
};
#define to_usb_bus(d) container_of(d, struct usb_bus, class_dev)
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