down_write_nest_lock() provides means to annotate locking scenario where
an outter lock is guaranteed to serialize the order nested locks are being
acquired.
This is an analogy to already existing mutex_lock_nest_lock() and
spin_lock_nest_lock().
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
---
include/linux/lockdep.h | 3 +++
include/linux/rwsem.h | 9 +++++++++
kernel/rwsem.c | 10 ++++++++++
3 files changed, 22 insertions(+), 0 deletions(-)
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 00e4637..2bca44b 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -524,14 +524,17 @@ static inline void print_irqtrace_events(struct task_struct *curr)
#ifdef CONFIG_DEBUG_LOCK_ALLOC
# ifdef CONFIG_PROVE_LOCKING
# define rwsem_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, NULL, i)
+# define rwsem_acquire_nest(l, s, t, n, i) lock_acquire(l, s, t, 0, 2, n, i)
# define rwsem_acquire_read(l, s, t, i) lock_acquire(l, s, t, 1, 2, NULL, i)
# else
# define rwsem_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, NULL, i)
+# define rwsem_acquire_nest(l, s, t, n, i) lock_acquire(l, s, t, 0, 1, n, i)
# define rwsem_acquire_read(l, s, t, i) lock_acquire(l, s, t, 1, 1, NULL, i)
# endif
# define rwsem_release(l, n, i) lock_release(l, n, i)
#else
# define rwsem_acquire(l, s, t, i) do { } while (0)
+# define rwsem_acquire_nest(l, s, t, n, i) do { } while (0)
# define rwsem_acquire_read(l, s, t, i) do { } while (0)
# define rwsem_release(l, n, i) do { } while (0)
#endif
diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
index 54bd7cd..413cc11 100644
--- a/include/linux/rwsem.h
+++ b/include/linux/rwsem.h
@@ -125,8 +125,17 @@ extern void downgrade_write(struct rw_semaphore *sem);
*/
extern void down_read_nested(struct rw_semaphore *sem, int subclass);
extern void down_write_nested(struct rw_semaphore *sem, int subclass);
+extern void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest_lock);
+
+# define down_write_nest_lock(sem, nest_lock) \
+do { \
+ typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
+ _down_write_nest_lock(sem, &(nest_lock)->dep_map); \
+} while (0);
+
#else
# define down_read_nested(sem, subclass) down_read(sem)
+# define down_write_nest_lock(sem, nest_lock) down_read(sem)
# define down_write_nested(sem, subclass) down_write(sem)
#endif
diff --git a/kernel/rwsem.c b/kernel/rwsem.c
index 6850f53..b3c6c3f 100644
--- a/kernel/rwsem.c
+++ b/kernel/rwsem.c
@@ -116,6 +116,16 @@ void down_read_nested(struct rw_semaphore *sem, int subclass)
EXPORT_SYMBOL(down_read_nested);
+void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest)
+{
+ might_sleep();
+ rwsem_acquire_nest(&sem->dep_map, 0, 0, nest, _RET_IP_);
+
+ LOCK_CONTENDED(sem, __down_write_trylock, __down_write);
+}
+
+EXPORT_SYMBOL(_down_write_nest_lock);
+
void down_write_nested(struct rw_semaphore *sem, int subclass)
{
might_sleep();
--
Jiri Kosina
SUSE Labs
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