[PATCH v2 5/8] percpu-rwsem: introduce percpu_rwsem_release() and percpu_rwsem_acquire()

Oleg Nesterov
2015-08-11T17:06:27Z

Add percpu_rwsem_release() and percpu_rwsem_acquire() for the users
which need to return to userspace with percpu-rwsem lock held and/or
pass the ownership to another thread.

TODO: change percpu_rwsem_release() to use rwsem_clear_owner(). We can
either fold kernel/locking/rwsem.h into include/linux/rwsem.h, or add
the non-inline percpu_rwsem_clear_owner().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
include/linux/percpu-rwsem.h | 19 +++++++++++++++++++
1 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h
index 3ebf982..06af654 100644
--- a/include/linux/percpu-rwsem.h
+++ b/include/linux/percpu-rwsem.h
@@ -33,4 +33,23 @@ extern void percpu_free_rwsem(struct percpu_rw_semaphore *);
__percpu_init_rwsem(brw, #brw, &rwsem_key); \
})

+
+#define percpu_rwsem_is_held(sem) lockdep_is_held(&(sem)->rw_sem)
+
+static inline void percpu_rwsem_release(struct percpu_rw_semaphore *sem,
+ bool read, unsigned long ip)
+{
+ lock_release(&sem->rw_sem.dep_map, 1, ip);
+#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
+ if (!read)
+ sem->rw_sem.owner = NULL;
+#endif
+}
+
+static inline void percpu_rwsem_acquire(struct percpu_rw_semaphore *sem,
+ bool read, unsigned long ip)
+{
+ lock_acquire(&sem->rw_sem.dep_map, 0, 1, read, 1, NULL, ip);
+}
+
#endif
--
1.5.5.1