Merge branch 'linus' into x86/cpu, to pick up fixes

[cascardo/linux.git] / drivers / usb / host / ehci-hub.c

diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index ffc9029..74f62d6 100644 (file)
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -872,14 +872,22 @@ int ehci_hub_control(
 ) {
        struct ehci_hcd *ehci = hcd_to_ehci (hcd);
        int             ports = HCS_N_PORTS (ehci->hcs_params);
-       u32 __iomem     *status_reg = &ehci->regs->port_status[
-                               (wIndex & 0xff) - 1];
-       u32 __iomem     *hostpc_reg = &ehci->regs->hostpc[(wIndex & 0xff) - 1];
+       u32 __iomem     *status_reg, *hostpc_reg;
        u32             temp, temp1, status;
        unsigned long   flags;
        int             retval = 0;
        unsigned        selector;
 
+       /*
+        * Avoid underflow while calculating (wIndex & 0xff) - 1.
+        * The compiler might deduce that wIndex can never be 0 and then
+        * optimize away the tests for !wIndex below.
+        */
+       temp = wIndex & 0xff;
+       temp -= (temp > 0);
+       status_reg = &ehci->regs->port_status[temp];
+       hostpc_reg = &ehci->regs->hostpc[temp];
+
        /*
         * FIXME:  support SetPortFeatures USB_PORT_FEAT_INDICATOR.
         * HCS_INDICATOR may say we can change LEDs to off/amber/green.