Subject: Re: [PATCH net-next RESEND 2/2] ipv6: fix sparse warning

From: "Paul E. McKenney" <[email-masked]>
Date: Wed, 10 Dec 2014 08:04:06 -0800

On Wed, Dec 10, 2014 at 04:46:07PM +0800, Ying Xue wrote:
> This fixes the following spare warning when using
> 
> make C=1 CF=-D__CHECK_ENDIAN__ net/ipv6/addrconf.o
> net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
> net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
> net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
> net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
> 
> To silence above spare complaint, 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_continue_rcu_bh().
> 
> By the way, this commit also resolves the same error appearing in
> hlist_for_each_entry_continue_rcu().
> 
> Signed-off-by: Ying Xue <[email-masked]>

If you pull the rculist.h changes from the first patch into this one,
I will queue it up through -rcu.

							Thanx, Paul

> ---
>  include/linux/rculist.h |   16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/include/linux/rculist.h b/include/linux/rculist.h
> index 866d9c9..32bd4ad 100644
> --- a/include/linux/rculist.h
> +++ b/include/linux/rculist.h
> @@ -524,11 +524,11 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
>   * @member:	the name of the hlist_node within the struct.
>   */
>  #define hlist_for_each_entry_continue_rcu(pos, member)			\
> -	for (pos = hlist_entry_safe(rcu_dereference((pos)->member.next),\
> -			typeof(*(pos)), member);			\
> +	for (pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \
> +			&(pos)->member)), typeof(*(pos)), member);	\
>  	     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))
> 
>  /**
>   * hlist_for_each_entry_continue_rcu_bh - iterate over a hlist continuing after current point
> @@ -536,11 +536,11 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
>   * @member:	the name of the hlist_node within the struct.
>   */
>  #define hlist_for_each_entry_continue_rcu_bh(pos, member)		\
> -	for (pos = hlist_entry_safe(rcu_dereference_bh((pos)->member.next),\
> -			typeof(*(pos)), member);			\
> +	for (pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu(  \
> +			&(pos)->member)), typeof(*(pos)), member);	\
>  	     pos;							\
> -	     pos = hlist_entry_safe(rcu_dereference_bh((pos)->member.next),\
> -			typeof(*(pos)), member))
> +	     pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu(	\
> +			&(pos)->member)), typeof(*(pos)), member))
> 
>  /**
>   * hlist_for_each_entry_from_rcu - iterate over a hlist continuing from current point
> -- 
> 1.7.9.5
>