USB: implement "soft" unbinding (9da82bd4) · Commits · 戴 / test

This patch (as1091) changes the way usbcore handles interface unbinding. If the interface's driver supports "soft" unbinding (a new flag in the driver structure) then in-flight URBs are not cancelled and endpoints are not disabled. Instead the driver is allowed to continue communicating with the device (although of course it should stop before its disconnect routine returns). The purpose of this change is to allow drivers to do a clean shutdown when they get unbound from a device that is still plugged in. Killing all the URBs and disabling the endpoints before calling the driver's disconnect method doesn't give the driver any control over what happens, and it can leave devices in indeterminate states. For example, when usb-storage unbinds it doesn't want to stop while in the middle of transmitting a SCSI command. The soft_unbind flag is added because in the past, a number of drivers have experienced problems related to ongoing I/O after their disconnect routine returned. Hence "soft" unbinding is made available only to drivers that claim to support it. The patch also replaces "interface_to_usbdev(intf)" with "udev" in a couple of places, a minor simplification. Signed-off-by:

Alan Stern <stern@rowland.harvard.edu> Signed-off-by:

Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/driver.c

+6 −5

Original line number	Diff line number	Diff line
		@@ -257,15 +257,16 @@ static int usb_unbind_interface(struct device *dev)
		udev = interface_to_usbdev(intf);
		error = usb_autoresume_device(udev);

		/* release all urbs for this interface */
		usb_disable_interface(interface_to_usbdev(intf), intf);
		/* Terminate all URBs for this interface unless the driver
		* supports "soft" unbinding.
		*/
		if (!driver->soft_unbind)
		usb_disable_interface(udev, intf);

		driver->disconnect(intf);

		/* reset other interface state */
		usb_set_interface(interface_to_usbdev(intf),
		intf->altsetting[0].desc.bInterfaceNumber,
		0);
		usb_set_interface(udev, intf->altsetting[0].desc.bInterfaceNumber, 0);
		usb_set_intfdata(intf, NULL);

		intf->condition = USB_INTERFACE_UNBOUND;

include/linux/usb.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -972,6 +972,8 @@ struct usbdrv_wrap {
		* added to this driver by preventing the sysfs file from being created.
		* @supports_autosuspend: if set to 0, the USB core will not allow autosuspend
		* for interfaces bound to this driver.
		* @soft_unbind: if set to 1, the USB core will not kill URBs and disable
		* endpoints before calling the driver's disconnect method.
		*
		* USB interface drivers must provide a name, probe() and disconnect()
		* methods, and an id_table. Other driver fields are optional.
		@@ -1012,6 +1014,7 @@ struct usb_driver {
		struct usbdrv_wrap drvwrap;
		unsigned int no_dynamic_id:1;
		unsigned int supports_autosuspend:1;
		unsigned int soft_unbind:1;
		};
		#define to_usb_driver(d) container_of(d, struct usb_driver, drvwrap.driver)

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