Re: [PATCH v2] lib: fix data race in rhashtable_rehash_one
From: Thomas Graf
Date: Tue Sep 22 2015 - 05:17:46 EST
On 09/22/15 at 10:51am, Dmitry Vyukov 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@xxxxxxxxxx>
Acked-by: Thomas Graf <tgraf@xxxxxxx>
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