xhci: harden xhci_find_next_ext_cap against device removal

[mirror_ubuntu-zesty-kernel.git] / drivers / usb / host / xhci-ext-caps.h

diff --git a/drivers/usb/host/xhci-ext-caps.h b/drivers/usb/host/xhci-ext-caps.h
index 04ce6b156b350e5dd0f9f9a321c79eb4d173b656..e0244fb3903dc85287f509bbac97600734c9b5af 100644 (file)
--- a/drivers/usb/host/xhci-ext-caps.h
+++ b/drivers/usb/host/xhci-ext-caps.h
@@ -112,12 +112,16 @@ static inline int xhci_find_next_ext_cap(void __iomem *base, u32 start, int id)
        offset = start;
        if (!start || start == XHCI_HCC_PARAMS_OFFSET) {
                val = readl(base + XHCI_HCC_PARAMS_OFFSET);
+               if (val == ~0)
+                       return 0;
                offset = XHCI_HCC_EXT_CAPS(val) << 2;
                if (!offset)
                        return 0;
        };
        do {
                val = readl(base + offset);
+               if (val == ~0)
+                       return 0;
                if (XHCI_EXT_CAPS_ID(val) == id && offset != start)
                        return offset;