Re: [PATCH v2] lib: fix data race in rhashtable_rehash_one

Dmitry Vyukov [off-list ref] wrote:

rhashtable_rehash_one() uses complex logic to update entry->next field,
after INIT_RHT_NULLS_HEAD and NULLS_MARKER expansion:

entry->next = 1 | ((base + off) << 1)

This can be compiled along the lines of:

entry->next = base + off
entry->next <<= 1
entry->next |= 1

Which will break concurrent readers.

NULLS value recomputation is not needed here, so just remove
the complex logic.

The data race was found with KernelThreadSanitizer (KTSAN).

Signed-off-by: Dmitry Vyukov <dvyukov@google.com>

Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
-- 
Email: Herbert Xu [off-list ref]
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