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SubjectRe: [LOCKDEP BUG][2.6.36-rc1] xt_info_wrlock?
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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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