[RFC PATCH 2/2] dma-buf/dma-resv: Improve the dma-resv lockdep checks

[Thomas Hellström]

Ensure that dma_resv_held() and dma_resv_assert_held() operate
on individual reservation objects within a WW transaction rather
than on the reservation WW class.

Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
---
 include/linux/dma-resv.h | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
index c5ab6fd9ebe8..001de3880fde 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -308,8 +308,11 @@ static inline bool dma_resv_iter_is_restarted(struct dma_resv_iter *cursor)
 	     fence = dma_resv_iter_first(cursor); fence;	\
 	     fence = dma_resv_iter_next(cursor))
 
-#define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
-#define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
+#define dma_resv_held(obj) (lockdep_is_held(&(obj)->lock.base) && ww_mutex_held(&(obj)->lock))
+#define dma_resv_assert_held(obj) do {			\
+		lockdep_assert_held(&(obj)->lock.base); \
+		ww_mutex_assert_held(&(obj)->lock);	\
+	} while (0)
 
 #ifdef CONFIG_DEBUG_MUTEXES
 void dma_resv_reset_max_fences(struct dma_resv *obj);
-- 
2.51.1