From: Oleg Nesterov <oleg@redhat.com>
Date: Tue, 21 Jul 2015 18:26:44 +0000 (+0200)
Subject: percpu-rwsem: introduce percpu_rwsem_release() and percpu_rwsem_acquire()
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=55cc156505f2e43fa45dbd4bfe8f9c9d848ca44c;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

percpu-rwsem: introduce percpu_rwsem_release() and percpu_rwsem_acquire()

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>
---

diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h
index 16c30cd33501..834c4e52cb2d 100644
--- a/include/linux/percpu-rwsem.h
+++ b/include/linux/percpu-rwsem.h
@@ -32,4 +32,23 @@ 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