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USB: add check to detect host controller hardware removal

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This patch (as1391) fixes a problem that can occur when USB host
controller hardware is hot-unplugged.  If no interrupts are generated
by the unplug then the HCD may not realize that the controller is
gone, and the subsequent unbind may hang waiting for interrupts that
never arrive.

The solution (for PCI-based controllers) is to call the HCD's
interrupt handler at the start of usb_hcd_pci_remove().  If the
hardware is gone, the handler will realize this when it tries to read
the controller's status register.

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 2010-06-09 17:34:27 -04:00 committed by Greg Kroah-Hartman
parent 6d88e67925
commit c548795abe
1 changed files with 8 additions and 0 deletions
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8
drivers/usb/core/hcd-pci.c
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@ -292,6 +292,14 @@ void usb_hcd_pci_remove(struct pci_dev *dev)
if (!hcd)
return;
/* Fake an interrupt request in order to give the driver a chance
* to test whether the controller hardware has been removed (e.g.,
* cardbus physical eject).
*/
local_irq_disable();
usb_hcd_irq(0, hcd);
local_irq_enable();
usb_remove_hcd(hcd);
if (hcd->driver->flags & HCD_MEMORY) {
iounmap(hcd->regs);