From: David Miller <davem@davemloft.net>
To: dvyukov@google.com
Cc: eric.dumazet@gmail.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, tgraf@suug.ch, kcc@google.com,
andreyknvl@google.com, glider@google.com, ktsan@googlegroups.com,
paulmck@linux.vnet.ibm.com
Subject: Re: [PATCH v2] lib: fix data race in rhashtable_rehash_one
Date: Tue, 22 Sep 2015 17:36:29 -0700 (PDT) [thread overview]
Message-ID: <20150922.173629.1910444040173069955.davem@davemloft.net> (raw)
In-Reply-To: <1442911912-66882-1-git-send-email-dvyukov@google.com>
From: Dmitry Vyukov <dvyukov@google.com>
Date: Tue, 22 Sep 2015 10:51:52 +0200
> 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>
Applied, thanks.
prev parent reply other threads:[~2015-09-23 0:36 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-22 8:51 [PATCH v2] lib: fix data race in rhashtable_rehash_one Dmitry Vyukov
2015-09-22 9:05 ` Eric Dumazet
2015-09-22 9:17 ` Thomas Graf
2015-09-22 15:19 ` Herbert Xu
2015-09-23 0:36 ` David Miller [this message]
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