RE: [PATCH BUGFIX 2/6] pkt_sched: fix the update of eligible-group sets

[David Laight]

> Between two invocations of make_eligible, the system virtual time may
> happen to grow enough that, in its binary representation, a bit with
> higher order than 31 flips. This happens especially with
> TSO/GSO. Before this fix, the mask used in make_eligible was computed
> as (1UL<<index_of_last_flipped_bit)-1, whose value is well defined on
> a 64-bit architecture, because index_of_flipped_bit <= 63, but is in
> general undefined on a 32-bit architecture if index_of_flipped_bit > 31.
> The fix just replaces 1UL with 1ULL.
...
> -		unsigned long mask = (1UL << fls(vslot ^ old_vslot)) - 1;
> +		unsigned long mask = (1ULL << fls(vslot ^ old_vslot)) - 1;

I'm not sure you really want to be doing 64bit shifts on 32 bit
systems just to generate ~0ul.
probably worth a conditional.

	David


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