WRITE_ONCE() is missing.

quoted

+               while (i >= 0) {
+                       qdisc_change_tx_queue_len(dev, &dev->_tx[i]);

What happens if one of these calls fails ?

I think a fix will be more complicated...

Hi Eric,
Given that pfifo_fast_change_tx_queue_len is currently the only
implementation of change_tx_queue_len, would it be reasonable to
handle partial failures solely within pfifo_fast_change_tx_queue_len
(which in turn leads to skb_array_resize_multiple_bh)? In other words,
is it sufficient to modify only the underlying low level
implementation of pfifo_fast_change_tx_queue_len for partial failures,
given that it's the sole implementation of change_tx_queue_len?