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Commit d5cbad4b authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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usbcore: khubd and busy-port handling 



We don't want khubd to start interfering in the device-resume process
merely because the PORT_STATUS_C_SUSPEND feature happens to be set.
Ports need to be marked as busy while a resume is taking place.

In addition, so long as ports are marked as busy, khubd won't be able to
clear their various status-change features.  On an interrupt-driven root
hub this could lead to an interrupt storm.  Root hub IRQs should not be
re-enabled until the busy_bits value is equal to 0.

This patch (as765) fixes these two potential problems.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 455b25fb

drivers/usb/core/hub.c

+10 −1
Original line number Diff line number Diff line
@@ -1658,6 +1658,8 @@ hub_port_resume(struct usb_hub *hub, int port1, struct usb_device *udev) 


	// dev_dbg(hub->intfdev, "resume port %d\n", port1);



	set_bit(port1, hub->busy_bits);



	/* see 7.1.7.7; affects power usage, but not budgeting */

	status = clear_port_feature(hub->hdev,

			port1, USB_PORT_FEAT_SUSPEND);
@@ -1707,6 +1709,10 @@ hub_port_resume(struct usb_hub *hub, int port1, struct usb_device *udev) 
	if (status < 0)

		hub_port_logical_disconnect(hub, port1);



	clear_bit(port1, hub->busy_bits);

	if (!hub->hdev->parent && !hub->busy_bits[0])

		usb_enable_root_hub_irq(hub->hdev->bus);



	return status;

}
@@ -2690,7 +2696,7 @@ static void hub_events(void) 


		/* If this is a root hub, tell the HCD it's okay to

		 * re-enable port-change interrupts now. */

		if (!hdev->parent)

		if (!hdev->parent && !hub->busy_bits[0])

			usb_enable_root_hub_irq(hdev->bus);



loop:
@@ -2865,6 +2871,9 @@ int usb_reset_device(struct usb_device *udev) 
			break;

	}

	clear_bit(port1, parent_hub->busy_bits);

	if (!parent_hdev->parent && !parent_hub->busy_bits[0])

		usb_enable_root_hub_irq(parent_hdev->bus);



	if (ret < 0)

		goto re_enumerate;

drivers/usb/core/hub.h

+2 −1
Original line number Diff line number Diff line
@@ -212,7 +212,8 @@ struct usb_hub { 
	unsigned long		event_bits[1];	/* status change bitmask */

	unsigned long		change_bits[1];	/* ports with logical connect

							status change */

	unsigned long		busy_bits[1];	/* ports being reset */

	unsigned long		busy_bits[1];	/* ports being reset or

							resumed */

#if USB_MAXCHILDREN > 31 /* 8*sizeof(unsigned long) - 1 */

#error event_bits[] is too short!

#endif