[PATCH v2 3/5] futex: Use RCU_INIT_POINTER() in futex_mm_init().

[Sebastian Andrzej Siewior]

There is no need for an explicit NULL pointer initialisation plus a
comment why it is okay. RCU_INIT_POINTER() can be used for NULL
initialisations and it is documented.

This has been build tested with gcc version 9.3.0 (Debian 9.3.0-22) on a
x86-64 defconfig.

Fixes: 094ac8cff7858 ("futex: Relax the rcu_assign_pointer() assignment of mm->futex_phash in futex_mm_init()")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
 include/linux/futex.h | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/include/linux/futex.h b/include/linux/futex.h
index 168ffd5996b48..005b040c4791b 100644
--- a/include/linux/futex.h
+++ b/include/linux/futex.h
@@ -88,14 +88,7 @@ void futex_hash_free(struct mm_struct *mm);
 
 static inline void futex_mm_init(struct mm_struct *mm)
 {
-	/*
-	 * No need for rcu_assign_pointer() here, as we can rely on
-	 * tasklist_lock write-ordering in copy_process(), before
-	 * the task's MM becomes visible and the ->futex_phash
-	 * becomes externally observable:
-	 */
-	mm->futex_phash = NULL;
-
+	RCU_INIT_POINTER(mm->futex_phash, NULL);
 	mutex_init(&mm->futex_hash_lock);
 }
 
-- 
2.49.0