Messages in this thread | | | Date | Wed, 25 Mar 2015 06:49:29 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH] rculist: Fix another sparse warning |
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On Wed, Mar 25, 2015 at 12:43:38PM +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@windriver.com>
If hlist_for_each_entry_from_rcu() is to use rcu_dereference_bh(), then it needs to be named hlist_for_each_entry_from_rcu_bh(). If we want to retain the generic nature, rcu_dereference_raw() would work.
(Otherwise, we would get splats if this was used under rcu_read_lock() rather than rcu_read_lock_bh().)
Thanx, 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..18a3f15 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_bh(hlist_next_rcu( \ > + &(pos)->member)), typeof(*(pos)), member)) > > #endif /* __KERNEL__ */ > #endif > -- > 1.7.9.5 >
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