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Subject[PATCH 1/2] lockdep: Markup callers of might_lock() as potential sleepers
Date
If might_lock() is called on a mutex, it may also potentially sleep.
Call might_sleep() in this case so that the caller is checked for both.
This is similar to the might_sleep() that is checked by the real
mutex_lock().

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
---
include/linux/lockdep.h | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index c1458fede1f9..0341e4246d00 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -549,9 +549,13 @@ static inline void print_irqtrace_events(struct task_struct *curr)
#define lock_map_acquire_tryread(l) lock_acquire_shared_recursive(l, 0, 1, NULL, _THIS_IP_)
#define lock_map_release(l) lock_release(l, 1, _THIS_IP_)

+#define lock_is_mutex(lock) \
+ __builtin_types_compatible_p(typeof(*lock), struct mutex)
+
#ifdef CONFIG_PROVE_LOCKING
# define might_lock(lock) \
do { \
+ might_sleep_if(lock_is_mutex(lock)); \
typecheck(struct lockdep_map *, &(lock)->dep_map); \
lock_acquire(&(lock)->dep_map, 0, 0, 0, 1, NULL, _THIS_IP_); \
lock_release(&(lock)->dep_map, 0, _THIS_IP_); \
@@ -563,7 +567,9 @@ do { \
lock_release(&(lock)->dep_map, 0, _THIS_IP_); \
} while (0)
#else
-# define might_lock(lock) do { } while (0)
+# define might_lock(lock) do { \
+ might_sleep_if(lock_is_mutex(lock)); \
+} while (0)
# define might_lock_read(lock) do { } while (0)
#endif

--
2.11.0
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