mmap locking API: add mmap_assert_locked() and mmap_assert_write_locked()

Add new APIs to assert that mmap_sem is held.

Using this instead of rwsem_is_locked and lockdep_assert_held[_write]
makes the assertions more tolerant of future changes to the lock type.

Signed-off-by: Michel Lespinasse <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Reviewed-by: Daniel Jordan <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: Laurent Dufour <[email protected]>
Cc: Liam Howlett <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ying Han <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 14 insertions, 0 deletions

diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h
index acac1bf5ecd2..43ef914e6468 100644
--- a/include/linux/mmap_lock.h
+++ b/include/linux/mmap_lock.h
@@ -1,6 +1,8 @@
 #ifndef _LINUX_MMAP_LOCK_H
 #define _LINUX_MMAP_LOCK_H
 
+#include <linux/mmdebug.h>
+
 #define MMAP_LOCK_INITIALIZER(name) \
 	.mmap_sem = __RWSEM_INITIALIZER((name).mmap_sem),
 
@@ -73,4 +75,16 @@ static inline void mmap_read_unlock_non_owner(struct mm_struct *mm)
 	up_read_non_owner(&mm->mmap_sem);
 }
 
+static inline void mmap_assert_locked(struct mm_struct *mm)
+{
+	lockdep_assert_held(&mm->mmap_sem);
+	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
+}
+
+static inline void mmap_assert_write_locked(struct mm_struct *mm)
+{
+	lockdep_assert_held_write(&mm->mmap_sem);
+	VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
+}
+
 #endif /* _LINUX_MMAP_LOCK_H */