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mm/mmu_notifier.c: remove mmu_notifier_synchronize()

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Contrary to its name, mmu_notifier_synchronize() does not synchronize the
notifier's SRCU instance, but rather waits for RCU callbacks to finish.
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.

Link: http://lkml.kernel.org/r/20181106134705.14197-1-sean.j.christopherson@intel.com
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Sean Christopherson 2018-12-28 00:33:28 -08:00 committed by Linus Torvalds
parent 5eb570a8d9
commit 6a90a83f1d
2 changed files with 0 additions and 8 deletions
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1
include/linux/mmu_notifier.h
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@ -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 */

7
mm/mmu_notifier.c
View File

@ -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