Re: [PATCH v2] rculist: Fix another sparse warning

From: Paul E. McKenney
Date: Fri Mar 27 2015 - 05:49:59 EST


On Thu, Mar 26, 2015 at 01:27:08PM +0800, Ying Xue wrote:
> This fixes the following sparse warnings:
>
> make C=1 CF=-D__CHECK_ENDIAN__ net/tipc/name_table.o
> net/tipc/name_table.c:977:17: error: incompatible types in comparison expression (different address spaces)
> net/tipc/name_table.c:977:17: error: incompatible types in comparison expression (different address spaces)
>
> To silence these spare complaints, an RCU annotation should be added to
> "next" pointer of hlist_node structure through hlist_next_rcu() macro
> when iterating over a hlist with hlist_for_each_entry_from_rcu().
>
> Signed-off-by: Ying Xue <ying.xue@xxxxxxxxxxxxx>

Queued for testing, thank you!

If testing goes well, I will push it into the 4.3 merge window.

Thanx, Paul

> ---
> Changes:
> - Replace rcu_dereference_bh() with rcu_dereference_raw() suggested
> by Paul.
>
> include/linux/rculist.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/rculist.h b/include/linux/rculist.h
> index a18b16f..fd1c870 100644
> --- a/include/linux/rculist.h
> +++ b/include/linux/rculist.h
> @@ -549,8 +549,8 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
> */
> #define hlist_for_each_entry_from_rcu(pos, member) \
> for (; pos; \
> - pos = hlist_entry_safe(rcu_dereference((pos)->member.next),\
> - typeof(*(pos)), member))
> + pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \
> + &(pos)->member)), typeof(*(pos)), member))
>
> #endif /* __KERNEL__ */
> #endif
> --
> 1.7.9.5
>

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