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mm/mmu_notifiers: hoist do_mmu_notifier_register down_write to the caller

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This simplifies the code to not have so many one line functions and extra
logic. __mmu_notifier_register() simply becomes the entry point to
register the notifier, and the other one calls it under lock.

Also add a lockdep_assert to check that the callers are holding the lock
as expected.

Link: https://lore.kernel.org/r/20190806231548.25242-2-jgg@ziepe.ca
Suggested-by: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Tested-by: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
This commit is contained in:
Jason Gunthorpe 2019-08-06 20:15:38 -03:00
parent 9c240a7bb3
commit 56c57103db
1 changed files with 14 additions and 21 deletions
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35
mm/mmu_notifier.c
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@ -236,22 +236,22 @@ void __mmu_notifier_invalidate_range(struct mm_struct *mm,
}
EXPORT_SYMBOL_GPL(__mmu_notifier_invalidate_range);
static int do_mmu_notifier_register(struct mmu_notifier *mn,
struct mm_struct *mm,
int take_mmap_sem)
/*
* Same as mmu_notifier_register but here the caller must hold the
* mmap_sem in write mode.
*/
int __mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm)
{
struct mmu_notifier_mm *mmu_notifier_mm;
int ret;
lockdep_assert_held_write(&mm->mmap_sem);
BUG_ON(atomic_read(&mm->mm_users) <= 0);
ret = -ENOMEM;
mmu_notifier_mm = kmalloc(sizeof(struct mmu_notifier_mm), GFP_KERNEL);
if (unlikely(!mmu_notifier_mm))
goto out;
return -ENOMEM;
if (take_mmap_sem)
down_write(&mm->mmap_sem);
ret = mm_take_all_locks(mm);
if (unlikely(ret))
goto out_clean;
@ -279,13 +279,11 @@ static int do_mmu_notifier_register(struct mmu_notifier *mn,
mm_drop_all_locks(mm);
out_clean:
if (take_mmap_sem)
up_write(&mm->mmap_sem);
kfree(mmu_notifier_mm);
out:
BUG_ON(atomic_read(&mm->mm_users) <= 0);
return ret;
}
EXPORT_SYMBOL_GPL(__mmu_notifier_register);
/*
* Must not hold mmap_sem nor any other VM related lock when calling
@ -302,20 +300,15 @@ static int do_mmu_notifier_register(struct mmu_notifier *mn,
*/
int mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm)
{
return do_mmu_notifier_register(mn, mm, 1);
int ret;
down_write(&mm->mmap_sem);
ret = __mmu_notifier_register(mn, mm);
up_write(&mm->mmap_sem);
return ret;
}
EXPORT_SYMBOL_GPL(mmu_notifier_register);
/*
* Same as mmu_notifier_register but here the caller must hold the
* mmap_sem in write mode.
*/
int __mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm)
{
return do_mmu_notifier_register(mn, mm, 0);
}
EXPORT_SYMBOL_GPL(__mmu_notifier_register);
/* this is called after the last mmu_notifier_unregister() returned */
void __mmu_notifier_mm_destroy(struct mm_struct *mm)
{