On Tue, Feb 07, 2017 at 02:17:28PM +0100, Florian Westphal wrote:

Ok, but why?

Because people expect the hash table insertion to succeed, even
on softirq paths where you cannot vmalloc.

It seems to add a whole lot of complexity...

What users can't handle the insert failure case until resize
has completed?

Users that need to insert on softirq that cannot throttle the
rate.

Would relaxing the max chain length (until rehash is done) be an
alternative?

Considering that this is intended for users that cannot throttle
the rate of insertion, I think we'd be much better off just failing
them than sticking them on what will essentially be a linked list.

As people don't like insertion failure, I think this level of
complexity is justified.

Cheers,
-- 
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