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

On Thu, Dec 11, 2014 at 09:56:33AM +0800, Ying Xue wrote:

On 12/11/2014 12:04 AM, Paul E. McKenney wrote:

quoted

On Wed, Dec 10, 2014 at 04:46:07PM +0800, Ying Xue wrote:

quoted

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 <redacted>

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

quoted

							Thanx, Paul

quoted

---
 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