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futex: Use RCU_INIT_POINTER() in futex_mm_init().

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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: 094ac8cff7 ("futex: Relax the rcu_assign_pointer() assignment of mm->futex_phash in futex_mm_init()")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250517151455.1065363-4-bigeasy@linutronix.de
This commit is contained in:
Sebastian Andrzej Siewior
2025-05-21 13:57:41 +02:00
committed by Peter Zijlstra
parent 7d4f494767
commit 279f2c2c8e
1 changed files with 1 additions and 8 deletions
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include/linux/futex.h
+1 -8
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@@ -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);
}