Commit 1b42ae6d authored Mar 13, 2007 by Alan Stern Committed by Greg Kroah-Hartman Apr 27, 2007

USB: fix race in HCD removal



This patch (as865) fixes a race in the HCD removal code discovered by
Milan Plzik.  Arrival of an interrupt after the root hub was
unregistered could cause the root-hub status timer to start up, even
after it was supposed to have been shut down.  The problem is fixed by
moving the del_timer_sync() call to after the HCD's stop() method, at
which time IRQ generation should be disabled.

Cc: Milan Plzik <milan.plzik@gmail.com>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

parent 949be0f7

drivers/usb/core/hcd.c

+5 −3

Original line number	Diff line number	Diff line
		@@ -544,6 +544,8 @@ void usb_hcd_poll_rh_status(struct usb_hcd *hcd)
		unsigned long flags;
		char buffer[4]; /* Any root hubs with > 31 ports? */

		if (unlikely(!hcd->rh_registered))
		return;
		if (!hcd->uses_new_polling && !hcd->status_urb)
		return;

		@@ -1670,12 +1672,12 @@ void usb_remove_hcd(struct usb_hcd *hcd)
		usb_disconnect(&hcd->self.root_hub);
		mutex_unlock(&usb_bus_list_lock);

		hcd->poll_rh = 0;
		del_timer_sync(&hcd->rh_timer);

		hcd->driver->stop(hcd);
		hcd->state = HC_STATE_HALT;

		hcd->poll_rh = 0;
		del_timer_sync(&hcd->rh_timer);

		if (hcd->irq >= 0)
		free_irq(hcd->irq, hcd);
		usb_deregister_bus(&hcd->self);

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