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usbcore: khubd and busy-port handling

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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: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern 2006-08-11 16:52:39 -04:00 committed by Greg Kroah-Hartman
parent 455b25fb20
commit d5cbad4b8b
2 changed files with 12 additions and 2 deletions
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11
drivers/usb/core/hub.c
View file

@ -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;

3
drivers/usb/core/hub.h
View file

@ -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