Contrary to its name, mmu_notifier_synchronize() does not synchronize
the notifier's SRCU instance, but rather waits for RCU callbacks to
finished, i.e. it invokes rcu_barrier(). The RCU documentation is
quite clear on this matter, explicitly calling out that rcu_barrier()
does not imply synchronize_rcu().
As there are no callers of mmu_notifier_synchronize() and it's unclear
whether any user of mmu_notifier_call_srcu() will ever want to barrier
on their callbacks, simply remove the function.
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
include/linux/mmu_notifier.h | 1 -
mm/mmu_notifier.c | 7 -------
2 files changed, 8 deletions(-)
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index 9893a6432adf..913c3c13e36e 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -420,7 +420,6 @@ static inline void mmu_notifier_mm_destroy(struct mm_struct *mm)
extern void mmu_notifier_call_srcu(struct rcu_head *rcu,
void (*func)(struct rcu_head *rcu));
-extern void mmu_notifier_synchronize(void);
#else /* CONFIG_MMU_NOTIFIER */
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 5119ff846769..755466cd289a 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -35,13 +35,6 @@ void mmu_notifier_call_srcu(struct rcu_head *rcu,
}
EXPORT_SYMBOL_GPL(mmu_notifier_call_srcu);
-void mmu_notifier_synchronize(void)
-{
- /* Wait for any running method to finish. */
- srcu_barrier(&srcu);
-}
-EXPORT_SYMBOL_GPL(mmu_notifier_synchronize);
-
/*
* This function can't run concurrently against mmu_notifier_register
* because mm->mm_users > 0 during mmu_notifier_register and exit_mmap
--
2.19.1
