The PM core reacts badly when the return code from usb_runtime_suspend() is not 0, -EAGAIN, or -EBUSY. The PM core regards this as a fatal error, and refuses to run anymore PM helper functions. In particular, usbfs_open() and other usbfs functions will fail because the PM core will return an error code when usb_autoresume_device() is called. This causes libusb and/or lsusb to either hang or segfault. If a USB device cannot suspend for some reason (e.g. a hub doesn't report it has remote wakeup capabilities), we still want lsusb and other userspace programs to work. So return -EBUSY, which will fill people's log files with failed tries, but will ensure userspace still works. Signed-off-by: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx> --- drivers/usb/core/driver.c | 5 +++++ 1 files changed, 5 insertions(+), 0 deletions(-) diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c index b9278a1..a6d9297 100644 --- a/drivers/usb/core/driver.c +++ b/drivers/usb/core/driver.c @@ -1660,6 +1660,11 @@ static int usb_runtime_suspend(struct device *dev) return -EAGAIN; status = usb_suspend_both(udev, PMSG_AUTO_SUSPEND); + /* The PM core reacts badly core unless the return code is 0, + * -EAGAIN, or -EBUSY, so always return -EBUSY on an error. + */ + if (status != 0) + return -EBUSY; return status; } -- 1.6.3.3 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
