1 files changed, 62 insertions, 5 deletions

diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
index efa5c324369a..f1aaf676a874 100644
--- a/include/linux/rwsem.h
+++ b/include/linux/rwsem.h
@@ -15,6 +15,7 @@
 #include <linux/spinlock.h>
 #include <linux/atomic.h>
 #include <linux/err.h>
+#include <linux/cleanup.h>
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 # define __RWSEM_DEP_MAP_INIT(lockname)			\
@@ -65,14 +66,24 @@ struct rw_semaphore {
 #endif
 };
 
-/* In all implementations count != 0 means locked */
+#define RWSEM_UNLOCKED_VALUE		0UL
+#define RWSEM_WRITER_LOCKED		(1UL << 0)
+#define __RWSEM_COUNT_INIT(name)	.count = ATOMIC_LONG_INIT(RWSEM_UNLOCKED_VALUE)
+
 static inline int rwsem_is_locked(struct rw_semaphore *sem)
 {
-	return atomic_long_read(&sem->count) != 0;
+	return atomic_long_read(&sem->count) != RWSEM_UNLOCKED_VALUE;
 }
 
-#define RWSEM_UNLOCKED_VALUE		0L
-#define __RWSEM_COUNT_INIT(name)	.count = ATOMIC_LONG_INIT(RWSEM_UNLOCKED_VALUE)
+static inline void rwsem_assert_held_nolockdep(const struct rw_semaphore *sem)
+{
+	WARN_ON(atomic_long_read(&sem->count) == RWSEM_UNLOCKED_VALUE);
+}
+
+static inline void rwsem_assert_held_write_nolockdep(const struct rw_semaphore *sem)
+{
+	WARN_ON(!(atomic_long_read(&sem->count) & RWSEM_WRITER_LOCKED));
+}
 
 /* Common initializer macros and functions */
 
@@ -121,6 +132,18 @@ static inline int rwsem_is_contended(struct rw_semaphore *sem)
 	return !list_empty(&sem->wait_list);
 }
 
+#if defined(CONFIG_DEBUG_RWSEMS) || defined(CONFIG_DETECT_HUNG_TASK_BLOCKER)
+/*
+ * Return just the real task structure pointer of the owner
+ */
+extern struct task_struct *rwsem_owner(struct rw_semaphore *sem);
+
+/*
+ * Return true if the rwsem is owned by a reader.
+ */
+extern bool is_rwsem_reader_owned(struct rw_semaphore *sem);
+#endif
+
 #else /* !CONFIG_PREEMPT_RT */
 
 #include <linux/rwbase_rt.h>
@@ -151,11 +174,21 @@ do {								\
 	__init_rwsem((sem), #sem, &__key);			\
 } while (0)
 
-static __always_inline int rwsem_is_locked(struct rw_semaphore *sem)
+static __always_inline int rwsem_is_locked(const struct rw_semaphore *sem)
 {
 	return rw_base_is_locked(&sem->rwbase);
 }
 
+static __always_inline void rwsem_assert_held_nolockdep(const struct rw_semaphore *sem)
+{
+	WARN_ON(!rwsem_is_locked(sem));
+}
+
+static __always_inline void rwsem_assert_held_write_nolockdep(const struct rw_semaphore *sem)
+{
+	WARN_ON(!rw_base_is_write_locked(&sem->rwbase));
+}
+
 static __always_inline int rwsem_is_contended(struct rw_semaphore *sem)
 {
 	return rw_base_is_contended(&sem->rwbase);
@@ -168,6 +201,22 @@ static __always_inline int rwsem_is_contended(struct rw_semaphore *sem)
  * the RT specific variant.
  */
 
+static inline void rwsem_assert_held(const struct rw_semaphore *sem)
+{
+	if (IS_ENABLED(CONFIG_LOCKDEP))
+		lockdep_assert_held(sem);
+	else
+		rwsem_assert_held_nolockdep(sem);
+}
+
+static inline void rwsem_assert_held_write(const struct rw_semaphore *sem)
+{
+	if (IS_ENABLED(CONFIG_LOCKDEP))
+		lockdep_assert_held_write(sem);
+	else
+		rwsem_assert_held_write_nolockdep(sem);
+}
+
 /*
  * lock for reading
  */
@@ -201,6 +250,14 @@ extern void up_read(struct rw_semaphore *sem);
  */
 extern void up_write(struct rw_semaphore *sem);
 
+DEFINE_GUARD(rwsem_read, struct rw_semaphore *, down_read(_T), up_read(_T))
+DEFINE_GUARD_COND(rwsem_read, _try, down_read_trylock(_T))
+DEFINE_GUARD_COND(rwsem_read, _intr, down_read_interruptible(_T), _RET == 0)
+
+DEFINE_GUARD(rwsem_write, struct rw_semaphore *, down_write(_T), up_write(_T))
+DEFINE_GUARD_COND(rwsem_write, _try, down_write_trylock(_T))
+DEFINE_GUARD_COND(rwsem_write, _kill, down_write_killable(_T), _RET == 0)
+
 /*
  * downgrade write lock to read lock
  */