It is considered good practice to call cpu_relax() in busy loops, see Documentation/process/volatile-considered-harmful.rst. This can lower CPU power consumption or yield to a hyperthreaded twin processor and also serve as a compiler barrier. In addition, if something goes wrong in the busy loop at least it can prevent things from getting worse. Signed-off-by: Zhongqiu Han <quic_zhonhan@xxxxxxxxxxx> --- drivers/usb/host/xhci-ext-caps.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/usb/host/xhci-ext-caps.h b/drivers/usb/host/xhci-ext-caps.h index 96eb36a58738..25d148d60ab0 100644 --- a/drivers/usb/host/xhci-ext-caps.h +++ b/drivers/usb/host/xhci-ext-caps.h @@ -144,6 +144,8 @@ static inline int xhci_find_next_ext_cap(void __iomem *base, u32 start, int id) if (offset != start && (id == 0 || XHCI_EXT_CAPS_ID(val) == id)) return offset; + cpu_relax(); + next = XHCI_EXT_CAPS_NEXT(val); offset += next << 2; } while (next); -- 2.25.1
