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* [PATCH v2] rculist: Fix another sparse warning
@ 2015-03-26  5:27 Ying Xue
  2015-03-27  9:49 ` Paul E. McKenney
  0 siblings, 1 reply; 2+ messages in thread
From: Ying Xue @ 2015-03-26  5:27 UTC (permalink / raw)
  To: paulmck; +Cc: linux-kernel

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>
---
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


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH v2] rculist: Fix another sparse warning
  2015-03-26  5:27 [PATCH v2] rculist: Fix another sparse warning Ying Xue
@ 2015-03-27  9:49 ` Paul E. McKenney
  0 siblings, 0 replies; 2+ messages in thread
From: Paul E. McKenney @ 2015-03-27  9:49 UTC (permalink / raw)
  To: Ying Xue; +Cc: linux-kernel

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@windriver.com>

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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