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

From: "Paul E. McKenney" <[email-masked]>
Date: Thu, 11 Dec 2014 09:02:10 -0800

On Thu, Dec 11, 2014 at 09:56:33AM +0800, Ying Xue wrote:
> On 12/11/2014 12:04 AM, Paul E. McKenney wrote:
> > 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.
> 
> Please just queue this patch into your RCU tree. Some changes of the
> first patch currently only exists in net-next tree, so it cannot be
> merged into RCU tree now. Therefore, please temporarily ignore it. In
> next 3.19 development cycle, I will resubmit it to you.

Sounds good, but could you please rebase the second patch to be
independent of the first patch?  If you do that, I would be happy
to queue it.

							Thanx, Paul

> Thanks,
> Ying
> 
> > 							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
> >>
> > 
> > 
> > 
>