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authorMathias Nyman <mathias.nyman@linux.intel.com>2017-01-11 17:10:34 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-01-19 20:17:20 +0100
commitd5fcd719e889213265311da4322821906c02a644 (patch)
treebb92cb1798780dcfeede08a2e522128fdd2eee16 /drivers/usb/host
parentae76af2518067cfbd9c3912f3c2558e5235b6e02 (diff)
xhci: fix deadlock at host remove by running watchdog correctly
commit d6169d04097fd9ddf811e63eae4e5cd71e6666e2 upstream. If a URB is killed while the host is removed we can end up in a situation where the hub thread takes the roothub device lock, and waits for the URB to be given back by xhci-hcd, blocking the host remove code. xhci-hcd tries to stop the endpoint and give back the urb, but can't as the host is removed from PCI bus at the same time, preventing the normal way of giving back urb. Instead we need to rely on the stop command timeout function to give back the urb. This xhci_stop_endpoint_command_watchdog() timeout function used a XHCI_STATE_DYING flag to indicate if the timeout function is already running, but later this flag has been taking into use in other places to mark that xhci is dying. Remove checks for XHCI_STATE_DYING in xhci_urb_dequeue. We are still checking that reading from pci state does not return 0xffffffff or that host is not halted before trying to stop the endpoint. This whole area of stopping endpoints, giving back URBs, and the wathdog timeout need rework, this fix focuses on solving a specific deadlock issue that we can then send to stable before any major rework. Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/host')
-rw-r--r--drivers/usb/host/xhci-ring.c11
-rw-r--r--drivers/usb/host/xhci.c13
2 files changed, 0 insertions, 24 deletions
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index fa5d8c2f6982..de7dce6eb474 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -913,17 +913,6 @@ void xhci_stop_endpoint_command_watchdog(unsigned long arg)
spin_lock_irqsave(&xhci->lock, flags);
ep->stop_cmds_pending--;
- if (xhci->xhc_state & XHCI_STATE_REMOVING) {
- spin_unlock_irqrestore(&xhci->lock, flags);
- return;
- }
- if (xhci->xhc_state & XHCI_STATE_DYING) {
- xhci_dbg_trace(xhci, trace_xhci_dbg_cancel_urb,
- "Stop EP timer ran, but another timer marked "
- "xHCI as DYING, exiting.");
- spin_unlock_irqrestore(&xhci->lock, flags);
- return;
- }
if (!(ep->stop_cmds_pending == 0 && (ep->ep_state & EP_HALT_PENDING))) {
xhci_dbg_trace(xhci, trace_xhci_dbg_cancel_urb,
"Stop EP timer ran, but no command pending, "
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index a8b3c0fc11fb..f2e9f59c90d6 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -1569,19 +1569,6 @@ int xhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
xhci_urb_free_priv(urb_priv);
return ret;
}
- if ((xhci->xhc_state & XHCI_STATE_DYING) ||
- (xhci->xhc_state & XHCI_STATE_HALTED)) {
- xhci_dbg_trace(xhci, trace_xhci_dbg_cancel_urb,
- "Ep 0x%x: URB %p to be canceled on "
- "non-responsive xHCI host.",
- urb->ep->desc.bEndpointAddress, urb);
- /* Let the stop endpoint command watchdog timer (which set this
- * state) finish cleaning up the endpoint TD lists. We must
- * have caught it in the middle of dropping a lock and giving
- * back an URB.
- */
- goto done;
- }
ep_index = xhci_get_endpoint_index(&urb->ep->desc);
ep = &xhci->devs[urb->dev->slot_id]->eps[ep_index];