usb: Always return 0 or -EBUSY to the runtime PM core.
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@linux.intel.com>
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index fca6172..38072e4 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -1659,6 +1659,11 @@
return -EAGAIN;
status = usb_suspend_both(udev, PMSG_AUTO_SUSPEND);
+ /* The PM core reacts badly unless the return code is 0,
+ * -EAGAIN, or -EBUSY, so always return -EBUSY on an error.
+ */
+ if (status != 0)
+ return -EBUSY;
return status;
}