Re: [PATCH 4/8] rhashtable: fix race in nested_table_alloc()

[Herbert Xu]

On Sun, May 06, 2018 at 07:48:20AM +1000, NeilBrown wrote:
>
> The spinlock protects 2 or more buckets.  The nested table contains at
> least 512 buckets, maybe more.
> It is quite possible for two insertions into 2 different buckets to both
> get their spinlock and both try to instantiate the same nested table.

I think you missed the fact that when we use nested tables the spin
lock table is limited to just a single page and hence corresponds
to the first level in the nested table.  Therefore it's always safe.

Cheers,
-- 
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt