[272/272] xhci: Use GFP_NOIO during device reset.

Greg KH
2011-02-16T00:26:10Z

From: Sarah Sharp <sarah.a.sharp@linux.intel.com>

commit a6d940dd759bf240d28624198660ed34582a327b upstream.

When xhci_discover_or_reset_device() is called after a host controller
power loss, the virtual device may need to be reallocated. Make sure
xhci_alloc_dev() uses GFP_NOIO. This avoid causing a deadlock by allowing
the kernel to flush pending I/O while reallocating memory for a virtual
device for a USB mass storage device that's holding the backing store for
dirty memory buffers.

This patch should be queued for the 2.6.37 stable tree.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/usb/host/xhci.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -2431,8 +2431,12 @@ int xhci_alloc_dev(struct usb_hcd *hcd,
xhci_err(xhci, "Error while assigning device slot ID\n");
return 0;
}
- /* xhci_alloc_virt_device() does not touch rings; no need to lock */
- if (!xhci_alloc_virt_device(xhci, xhci->slot_id, udev, GFP_KERNEL)) {
+ /* xhci_alloc_virt_device() does not touch rings; no need to lock.
+ * Use GFP_NOIO, since this function can be called from
+ * xhci_discover_or_reset_device(), which may be called as part of
+ * mass storage driver error handling.
+ */
+ if (!xhci_alloc_virt_device(xhci, xhci->slot_id, udev, GFP_NOIO)) {
/* Disable slot, if we can do it without mem alloc */
xhci_warn(xhci, "Could not allocate xHCI USB device data structures\n");
spin_lock_irqsave(&xhci->lock, flags);