[RFT,1/2] xhci: Fix leaking USB3 shared_hcd at xhci removal

[Mathias Nyman <mathias.nyman@linux.intel.com>]

Ensure that the shared_hcd pointer is valid when calling usb_put_hcd()

The shared_hcd is removed and freed in xhci by first calling
usb_remove_hcd(xhci->shared_hcd), and later
usb_put_hcd(xhci->shared_hcd)

Afer commit fe190ed0d602 ("xhci: Do not halt the host until both HCD have
disconnected their devices.") the shared_hcd was never properly put as
xhci->shared_hcd was set to NULL before usb_put_hcd(xhci->shared_hcd) was
called.

shared_hcd (USB3) is removed before primary hcd (USB2).
While removing the primary hcd we might need to handle xhci interrupts
to cleanly remove last USB2 devices, therefore we need to set
xhci->shared_hcd to NULL before removing the primary hcd to let xhci
interrupt handler know shared_hcd is no longer available.

xhci-plat.c, xhci-histb.c and xhci-mtk first create both their hcd's before
adding them. so to keep the correct reverse removal order use a temporary
shared_hcd variable for them.
For more details see commit 4ac53087d6d4 ("usb: xhci: plat: Create both
HCDs before adding them")

Fixes: fe190ed0d602 ("xhci: Do not halt the host until both HCD have disconnected their devices.")
Cc: Joel Stanley <joel@jms.id.au>
Cc: Chunfeng Yun <chunfeng.yun@mediatek.com>
Cc: Thierry Reding <treding@nvidia.com>
Cc: Jianguo Sun <sunjianguo1@huawei.com>
Cc: <stable@vger.kernel.org>
Reported-by: Jack Pham <jackp@codeaurora.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
---
 drivers/usb/host/xhci-histb.c | 6 ++++--
 drivers/usb/host/xhci-mtk.c   | 6 ++++--
 drivers/usb/host/xhci-pci.c   | 1 +
 drivers/usb/host/xhci-plat.c  | 6 ++++--
 drivers/usb/host/xhci-tegra.c | 1 +
 drivers/usb/host/xhci.c       | 2 --
 6 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/usb/host/xhci-histb.c b/drivers/usb/host/xhci-histb.c
index 27f0016..3c4abb5 100644
--- a/drivers/usb/host/xhci-histb.c
+++ b/drivers/usb/host/xhci-histb.c
@@ -325,14 +325,16 @@ static int xhci_histb_remove(struct platform_device *dev)
 	struct xhci_hcd_histb *histb = platform_get_drvdata(dev);
 	struct usb_hcd *hcd = histb->hcd;
 	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
+	struct usb_hcd *shared_hcd = xhci->shared_hcd;
 
 	xhci->xhc_state |= XHCI_STATE_REMOVING;
 
-	usb_remove_hcd(xhci->shared_hcd);
+	usb_remove_hcd(shared_hcd);
+	xhci->shared_hcd = NULL;
 	device_wakeup_disable(&dev->dev);
 
 	usb_remove_hcd(hcd);
-	usb_put_hcd(xhci->shared_hcd);
+	usb_put_hcd(shared_hcd);
 
 	xhci_histb_host_disable(histb);
 	usb_put_hcd(hcd);
diff --git a/drivers/usb/host/xhci-mtk.c b/drivers/usb/host/xhci-mtk.c
index 71d0d33..60987c7 100644
--- a/drivers/usb/host/xhci-mtk.c
+++ b/drivers/usb/host/xhci-mtk.c
@@ -590,12 +590,14 @@ static int xhci_mtk_remove(struct platform_device *dev)
 	struct xhci_hcd_mtk *mtk = platform_get_drvdata(dev);
 	struct usb_hcd	*hcd = mtk->hcd;
 	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
+	struct usb_hcd  *shared_hcd = xhci->shared_hcd;
 
-	usb_remove_hcd(xhci->shared_hcd);
+	usb_remove_hcd(shared_hcd);
+	xhci->shared_hcd = NULL;
 	device_init_wakeup(&dev->dev, false);
 
 	usb_remove_hcd(hcd);
-	usb_put_hcd(xhci->shared_hcd);
+	usb_put_hcd(shared_hcd);
 	usb_put_hcd(hcd);
 	xhci_mtk_sch_exit(mtk);
 	xhci_mtk_clks_disable(mtk);
diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index 51dd8e0..92fd6b6 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -356,6 +356,7 @@ static void xhci_pci_remove(struct pci_dev *dev)
 	if (xhci->shared_hcd) {
 		usb_remove_hcd(xhci->shared_hcd);
 		usb_put_hcd(xhci->shared_hcd);
+		xhci->shared_hcd = NULL;
 	}
 
 	/* Workaround for spurious wakeups at shutdown with HSW */
diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index 94e9392..e5da8ce 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -359,14 +359,16 @@ static int xhci_plat_remove(struct platform_device *dev)
 	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
 	struct clk *clk = xhci->clk;
 	struct clk *reg_clk = xhci->reg_clk;
+	struct usb_hcd *shared_hcd = xhci->shared_hcd;
 
 	xhci->xhc_state |= XHCI_STATE_REMOVING;
 
-	usb_remove_hcd(xhci->shared_hcd);
+	usb_remove_hcd(shared_hcd);
+	xhci->shared_hcd = NULL;
 	usb_phy_shutdown(hcd->usb_phy);
 
 	usb_remove_hcd(hcd);
-	usb_put_hcd(xhci->shared_hcd);
+	usb_put_hcd(shared_hcd);
 
 	clk_disable_unprepare(clk);
 	clk_disable_unprepare(reg_clk);
diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
index 4b463e5..b1cce98 100644
--- a/drivers/usb/host/xhci-tegra.c
+++ b/drivers/usb/host/xhci-tegra.c
@@ -1240,6 +1240,7 @@ static int tegra_xusb_remove(struct platform_device *pdev)
 
 	usb_remove_hcd(xhci->shared_hcd);
 	usb_put_hcd(xhci->shared_hcd);
+	xhci->shared_hcd = NULL;
 	usb_remove_hcd(tegra->hcd);
 	usb_put_hcd(tegra->hcd);
 
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 0420eef..c928dbb 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -719,8 +719,6 @@ static void xhci_stop(struct usb_hcd *hcd)
 
 	/* Only halt host and free memory after both hcds are removed */
 	if (!usb_hcd_is_primary_hcd(hcd)) {
-		/* usb core will free this hcd shortly, unset pointer */
-		xhci->shared_hcd = NULL;
 		mutex_unlock(&xhci->mutex);
 		return;
 	}