Patch "xhci: fix 10 second timeout on removal of PCI hotpluggable xhci controllers" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

xhci: fix 10 second timeout on removal of PCI hotpluggable xhci controllers

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
xhci-fix-10-second-timeout-on-removal-of-pci-hotpluggable-xhci-controllers.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Mathias Nyman <[email protected]>
Date: Fri, 8 Apr 2016 16:25:10 +0300
Subject: xhci: fix 10 second timeout on removal of PCI hotpluggable xhci controllers

From: Mathias Nyman <[email protected]>

commit 98d74f9ceaefc2b6c4a6440050163a83be0abede upstream.

PCI hotpluggable xhci controllers such as some Alpine Ridge solutions will remove the xhci controller from the PCI bus when the last USB device is disconnected.

Add a flag to indicate that the host is being removed to avoid queueing configure_endpoint commands for the dropped endpoints.
For PCI hotplugged controllers this will prevent 5 second command timeouts For static xhci controllers the configure_endpoint command is not needed in the removal case as everything will be returned, freed, and the controller is reset.

For now the flag is only set for PCI connected host controllers.

---
 drivers/usb/host/xhci-pci.c  |    1 +
 drivers/usb/host/xhci-ring.c |    3 ++-
 drivers/usb/host/xhci.c      |    8 +++++---
 drivers/usb/host/xhci.h      |    1 +
 4 files changed, 9 insertions(+), 4 deletions(-)

@@ -301,6 +301,7 @@ static void xhci_pci_remove(struct pci_d
 	struct xhci_hcd *xhci;
 
 	xhci = hcd_to_xhci(pci_get_drvdata(dev));
+	xhci->xhc_state |= XHCI_STATE_REMOVING;
 	if (xhci->shared_hcd) {
 		usb_remove_hcd(xhci->shared_hcd);
 		usb_put_hcd(xhci->shared_hcd);

@@ -4008,7 +4008,8 @@ static int queue_command(struct xhci_hcd
 	int reserved_trbs = xhci->cmd_ring_reserved_trbs;
 	int ret;
 
-	if (xhci->xhc_state) {
+	if ((xhci->xhc_state & XHCI_STATE_DYING) ||
+		(xhci->xhc_state & XHCI_STATE_HALTED)) {
 		xhci_dbg(xhci, "xHCI dying or halted, can't queue_command\n");
 		return -ESHUTDOWN;
 	}

@@ -146,7 +146,8 @@ static int xhci_start(struct xhci_hcd *x
 				"waited %u microseconds.\n",
 				XHCI_MAX_HALT_USEC);
 	if (!ret)
-		xhci->xhc_state &= ~(XHCI_STATE_HALTED | XHCI_STATE_DYING);
+		/* clear state flags. Including dying, halted or removing */
+		xhci->xhc_state = 0;
 
 	return ret;
 }

@@ -2753,7 +2754,8 @@ int xhci_check_bandwidth(struct usb_hcd
 	if (ret <= 0)
 		return ret;
 	xhci = hcd_to_xhci(hcd);
-	if (xhci->xhc_state & XHCI_STATE_DYING)
+	if ((xhci->xhc_state & XHCI_STATE_DYING) ||
+		(xhci->xhc_state & XHCI_STATE_REMOVING))
 		return -ENODEV;
 
 	xhci_dbg(xhci, "%s called for udev %p\n", __func__, udev);

@@ -3800,7 +3802,7 @@ static int xhci_setup_device(struct usb_
 
 	mutex_lock(&xhci->mutex);
 
-	if (xhci->xhc_state)	/* dying or halted */
+	if (xhci->xhc_state)	/* dying, removing or halted */
 		goto out;
 
 	if (!udev->slot_id) {

@@ -1596,6 +1596,7 @@ struct xhci_hcd {
  */
 #define XHCI_STATE_DYING	(1 << 0)
 #define XHCI_STATE_HALTED	(1 << 1)
+#define XHCI_STATE_REMOVING	(1 << 2)
 	/* Statistics */
 	int			error_bitmask;
 	unsigned int		quirks;

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/usb-xhci-applying-xhci_pme_stuck_quirk-to-intel-bxt-b0-host.patch queue-4.4/xhci-resume-usb-3-roothub-first.patch queue-4.4/xhci-fix-10-second-timeout-on-removal-of-pci-hotpluggable-xhci-controllers.patch queue-4.4/usb-xhci-fix-wild-pointers-in-xhci_mem_cleanup.patch