Messages in this thread | | | Date | Tue, 21 Apr 2020 19:18:50 -0700 | From | Matthew Wilcox <> | Subject | Re: [PATCH v5 09/10] mmap locking API: add mmap_assert_locked |
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On Tue, Apr 21, 2020 at 07:10:39PM -0700, Michel Lespinasse wrote: > On Tue, Apr 21, 2020 at 5:14 PM Michel Lespinasse <walken@google.com> 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.
Oops, sorry. It only defines
#define lockdep_is_held_type(l, r) (1) #define lockdep_assert_held(l) do { (void)(l); } while (0) #define lockdep_assert_held_write(l) do { (void)(l); } while (0) #define lockdep_assert_held_read(l) do { (void)(l); } while (0) #define lockdep_assert_held_once(l) do { (void)(l); } while (0)
which seems like an oversight, but not one that you should be fixing.
> 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); > }
Yes, I agree.
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