[PATCH v4 07/35] lockdep: Annotate lockdep assertions for context analysis

[Marco Elver]

Clang's context analysis can be made aware of functions that assert that
locks are held.

Presence of these annotations causes the analysis to assume the context
guard is held after calls to the annotated function, and avoid false
positives with complex control-flow; for example, where not all
control-flow paths in a function require a held lock, and therefore
marking the function with __must_hold(..) is inappropriate.

Signed-off-by: Marco Elver <elver at google.com>
---
v4:
* Rename capability -> context analysis.

v3:
* __assert -> __assume rename
---
 include/linux/lockdep.h | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 67964dc4db95..2c99a6823161 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -282,16 +282,16 @@ extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
 	do { WARN_ON_ONCE(debug_locks && !(cond)); } while (0)
 
 #define lockdep_assert_held(l)		\
-	lockdep_assert(lockdep_is_held(l) != LOCK_STATE_NOT_HELD)
+	do { lockdep_assert(lockdep_is_held(l) != LOCK_STATE_NOT_HELD); __assume_ctx_guard(l); } while (0)
 
 #define lockdep_assert_not_held(l)	\
 	lockdep_assert(lockdep_is_held(l) != LOCK_STATE_HELD)
 
 #define lockdep_assert_held_write(l)	\
-	lockdep_assert(lockdep_is_held_type(l, 0))
+	do { lockdep_assert(lockdep_is_held_type(l, 0)); __assume_ctx_guard(l); } while (0)
 
 #define lockdep_assert_held_read(l)	\
-	lockdep_assert(lockdep_is_held_type(l, 1))
+	do { lockdep_assert(lockdep_is_held_type(l, 1)); __assume_shared_ctx_guard(l); } while (0)
 
 #define lockdep_assert_held_once(l)		\
 	lockdep_assert_once(lockdep_is_held(l) != LOCK_STATE_NOT_HELD)
@@ -389,10 +389,10 @@ extern int lockdep_is_held(const void *);
 #define lockdep_assert(c)			do { } while (0)
 #define lockdep_assert_once(c)			do { } while (0)
 
-#define lockdep_assert_held(l)			do { (void)(l); } while (0)
+#define lockdep_assert_held(l)			__assume_ctx_guard(l)
 #define lockdep_assert_not_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_write(l)		__assume_ctx_guard(l)
+#define lockdep_assert_held_read(l)		__assume_shared_ctx_guard(l)
 #define lockdep_assert_held_once(l)		do { (void)(l); } while (0)
 #define lockdep_assert_none_held_once()	do { } while (0)
 
-- 
2.52.0.rc1.455.g30608eb744-goog