Messages in this thread | | | Date | Mon, 19 Nov 2018 11:56:35 +0800 | From | Herbert Xu <> | Subject | Re: [PATCH] rhashtable: detect when object movement between tables might have invalidated a lookup |
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On Mon, Nov 19, 2018 at 11:54:15AM +0800, Herbert Xu wrote: > > > >> diff --git a/lib/rhashtable.c b/lib/rhashtable.c > > >> index 30526afa8343..852ffa5160f1 100644 > > >> --- a/lib/rhashtable.c > > >> +++ b/lib/rhashtable.c > > >> @@ -1179,8 +1179,7 @@ struct rhash_head __rcu **rht_bucket_nested(const struct bucket_table *tbl, > > >> unsigned int hash) > > >> { > > >> const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *)); > > >> - static struct rhash_head __rcu *rhnull = > > >> - (struct rhash_head __rcu *)NULLS_MARKER(0); > > >> + static struct rhash_head __rcu *rhnull; > > > > > > I don't understand why you can't continue to do NULLS_MARKER(0) or > > > RHT_NULLS_MARKER(0). > > > > Because then the test > > > > + } while (he != RHT_NULLS_MARKER(head)); > > > > in __rhashtable_lookup() would always succeed, and it would loop > > forever. > > This change is only necessary because of your shifting change > above, which AFAICS adds no real benefit.
I take that back. Because of your shift which cancels out the shift in NULLS_MARKER, it would appear that this should work just fine with RHT_NULLS_MARRKER(0), no? IOW, it would appear that
RHT_NULLS_MARKER(0) = RHT_NULLS_MARKER(RHT_NULLS_MARKER(0))
Thanks, -- Email: Herbert Xu <herbert@gondor.apana.org.au> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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