Linux: Don't print errors when cancel_transfer fails with NOT_FOUND

* Under some cricumstances, LIBUSB_ERROR_NOT_FOUND is an expected
  return value for cancel_transfer so printing an error is undesirable.

diff --git a/libusb/io.c b/libusb/io.c
index bb04a8f..c9df0cf 100644 (file)
--- a/libusb/io.c
+++ b/libusb/io.c
@@ -1353,8 +1353,11 @@ int API_EXPORTED libusb_cancel_transfer(struct libusb_transfer *transfer)
        usbi_mutex_lock(&itransfer->lock);
        r = usbi_backend->cancel_transfer(itransfer);
        if (r < 0) {
-               usbi_err(TRANSFER_CTX(transfer),
-                       "cancel transfer failed error %d", r);
+               if (r != LIBUSB_ERROR_NOT_FOUND)
+                       usbi_err(TRANSFER_CTX(transfer),
+                               "cancel transfer failed error %d", r);
+               else
+                       usbi_dbg("cancel transfer failed error %d", r);
 
                if (r == LIBUSB_ERROR_NO_DEVICE)
                        itransfer->flags |= USBI_TRANSFER_DEVICE_DISAPPEARED;