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[RFC,5/5] rcuwait: Replace rcu_assign_pointer() with WRITE_ONCE

Message ID 20190221054942.132388-6-joel@joelfernandes.org
State RFC
Delegated to: David Miller
Headers show
Series RCU fixes for rcu_assign_pointer() usage | expand

Commit Message

Joel Fernandes Feb. 21, 2019, 5:49 a.m. UTC 
This suppresses a sparse error generated due to the recently added
rcu_assign_pointer sparse check below. It seems WRITE_ONCE should be
sufficient here.

>> kernel//locking/percpu-rwsem.c:162:9: sparse: error: incompatible
types in comparison expression (different address spaces)

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
 include/linux/rcuwait.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Peter Zijlstra Feb. 21, 2019, 9:20 a.m. UTC | #1 
On Thu, Feb 21, 2019 at 12:49:42AM -0500, Joel Fernandes (Google) wrote:
> This suppresses a sparse error generated due to the recently added
> rcu_assign_pointer sparse check below. It seems WRITE_ONCE should be
> sufficient here.
> 
> >> kernel//locking/percpu-rwsem.c:162:9: sparse: error: incompatible
> types in comparison expression (different address spaces)
> 
> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
> ---
>  include/linux/rcuwait.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/rcuwait.h b/include/linux/rcuwait.h
> index 90bfa3279a01..9e5b4760e6c2 100644
> --- a/include/linux/rcuwait.h
> +++ b/include/linux/rcuwait.h
> @@ -44,7 +44,7 @@ extern void rcuwait_wake_up(struct rcuwait *w);
>  	 */                                                             \
>  	WARN_ON(current->exit_state);                                   \
>  									\
> -	rcu_assign_pointer((w)->task, current);				\
> +	WRITE_ONCE((w)->task, current);					\
>  	for (;;) {							\
>  		/*							\
>  		 * Implicit barrier (A) pairs with (B) in		\

Distinct lack of justification for loosing the RELEASE again.
diff mbox series

Patch

diff --git a/include/linux/rcuwait.h b/include/linux/rcuwait.h
index 90bfa3279a01..9e5b4760e6c2 100644
--- a/include/linux/rcuwait.h
+++ b/include/linux/rcuwait.h
@@ -44,7 +44,7 @@  extern void rcuwait_wake_up(struct rcuwait *w);
 	 */                                                             \
 	WARN_ON(current->exit_state);                                   \
 									\
-	rcu_assign_pointer((w)->task, current);				\
+	WRITE_ONCE((w)->task, current);					\
 	for (;;) {							\
 		/*							\
 		 * Implicit barrier (A) pairs with (B) in		\