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    SubjectRe: [LOCKDEP BUG][2.6.36-rc1] xt_info_wrlock?
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    Date
    On Mon, 2010-08-16 at 12:44 -0700, David Miller wrote:
    > He's only accessing the per-cpu counter locks of other cpus.
    >
    > The per-cpu lock is only locally accessed by a cpu in software
    > interrupt context.
    >
    > That is why his transformation is legal.
    >
    > Lockdep simply hasn't been informed of this invariant and has
    > to assume the worst.

    Something like the below will keep lockdep coverage, still going back to
    RCU sounds like the best option.

    ---
    include/linux/netfilter/x_tables.h | 9 +++++++++
    1 files changed, 9 insertions(+), 0 deletions(-)

    diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h
    index 24e5d01..a195feb 100644
    --- a/include/linux/netfilter/x_tables.h
    +++ b/include/linux/netfilter/x_tables.h
    @@ -511,12 +511,21 @@ static inline void xt_info_rdunlock_bh(void)
    */
    static inline void xt_info_wrlock(unsigned int cpu)
    {
    +#ifdef CONFIG_PROVE_LOCKING
    + /*
    + * XXX foo
    + */
    + local_bh_disable();
    +#endif
    spin_lock(&per_cpu(xt_info_locks, cpu).lock);
    }

    static inline void xt_info_wrunlock(unsigned int cpu)
    {
    spin_unlock(&per_cpu(xt_info_locks, cpu).lock);
    +#ifdef CONFIG_PROVE_LOCKING
    + local_bh_enable();
    +#endif
    }

    /*


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