[PATCH 2/3] lockdep: add might_lock_nested()

[Daniel Vetter]

Necessary to annotate functions where we might acquire a
mutex_lock_nested() or similar. Needed by i915.

Signed-off-by: Daniel Vetter <daniel.vet...@intel.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: Will Deacon <w...@kernel.org>
Cc: linux-ker...@vger.kernel.org
---
 include/linux/lockdep.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 38ea6178df7d..30f6172d6889 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -631,6 +631,13 @@ do {                                                       
                \
        lock_acquire(&(lock)->dep_map, 0, 0, 1, 1, NULL, _THIS_IP_);    \
        lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 } while (0)
+# define might_lock_nested(lock, subclass)                             \
+do {                                                                   \
+       typecheck(struct lockdep_map *, &(lock)->dep_map);              \
+       lock_acquire(&(lock)->dep_map, subclass, 0, 1, 1, NULL,         \
+                    _THIS_IP_);                                        \
+       lock_release(&(lock)->dep_map, 0, _THIS_IP_);           \
+} while (0)
 
 #define lockdep_assert_irqs_enabled()  do {                            \
                WARN_ONCE(debug_locks && !current->lockdep_recursion && \
@@ -653,6 +660,7 @@ do {                                                        
                \
 #else
 # define might_lock(lock) do { } while (0)
 # define might_lock_read(lock) do { } while (0)
+# define might_lock_nested(lock, subclass) do { } while (0)
 # define lockdep_assert_irqs_enabled() do { } while (0)
 # define lockdep_assert_irqs_disabled() do { } while (0)
 # define lockdep_assert_in_irq() do { } while (0)
-- 
2.23.0.rc1