corresponding bitmap before adding an mbuf has actually succeeded.
Previously, m_gethdr(M_NOWAIT, ...) failing caused a "hole" in the
RX ring but not in its bitmap. One implication of such a hole was
that in a subsequent call to _iflib_fl_refill() with the RX buffer
accounting still indicating another reclaimable buffer, bit_ffc(3)
nevertheless returned -1 in frag_idx which in turn caused havoc
when used as an index. Thus, additionally assert that frag_idx is
0 or greater.
Another possible consequence of a hole in the RX ring was a NULL-
dereference when trying to use the unallocated mbuf, for example
in iflib_rxd_pkt_get().
While at it, make the variable declarations in _iflib_fl_refill()
conform to style(9) and remove redundant checks already performed
by bit_ffc{,_at}(3).
- In iflib_queues_alloc(), don't pass redundant M_ZERO to bit_alloc(3).
Reported and tested by: pho
3db348b54a