Re: [PATCH v5 09/10] mmap locking API: add mmap_assert_locked

[Michel Lespinasse]

On Tue, Apr 21, 2020 at 5:14 PM Michel Lespinasse <walken@xxxxxxxxxx> wrote:
> +static inline void mmap_assert_locked(struct mm_struct *mm)
> +{
> +       if (IS_ENABLED(CONFIG_LOCKDEP) && debug_locks)
> +               VM_BUG_ON_MM(!lockdep_is_held(&mm->mmap_sem), mm);
> +       else
> +               VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
> +}

Turns out this function definition does not work for !CONFIG_LOCKDEP
as lockdep_is_held is not defined in that case.

The following should work instead:

static inline void mmap_assert_locked(struct mm_struct *mm)
{
#ifdef CONFIG_LOCKDEP
        if (debug_locks) {
                VM_BUG_ON_MM(!lockdep_is_held(&mm->mmap_lock), mm);
                return;
        }
#endif
        VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);
}