linux-kernel - [PATCH 4.2.y-ckt 48/93] xhci: fix 10 second timeout on removal of PCI hotpluggable xhci controllers

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Date:	Tue, 26 Apr 2016 11:16:48 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Mathias Nyman <mathias.nyman@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 48/93] xhci: fix 10 second timeout on removal of PCI hotpluggable xhci controllers

4.2.8-ckt9 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Mathias Nyman <mathias.nyman@...ux.intel.com>

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.

Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 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(-)

diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index 08fb12f..6494798 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -303,6 +303,7 @@ static void xhci_pci_remove(struct pci_dev *dev)
 	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);
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index ea9690e..c7fe14b 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -3843,7 +3843,8 @@ static int queue_command(struct xhci_hcd *xhci, struct xhci_command *cmd,
 	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;
 	}
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 21f638d..c718b22 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -146,7 +146,8 @@ static int xhci_start(struct xhci_hcd *xhci)
 				"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 *hcd, struct usb_device *udev)
 	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_hcd *hcd, struct usb_device *udev,
 
 	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) {
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 82be4b5..79b95de 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1534,6 +1534,7 @@ 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;
-- 
2.7.4