locking/percpu-rwsem: Add DEFINE_PERCPU_RWSEM(), use it to initialize cgroup_threadgr...

Turn DEFINE_STATIC_PERCPU_RWSEM() into __DEFINE_PERCPU_RWSEM() with the
additional "is_static" argument to introduce DEFINE_PERCPU_RWSEM().

Change cgroup.c to use DEFINE_PERCPU_RWSEM(cgroup_threadgroup_rwsem).

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h
index 6887636..2809b44 100644 (file)
--- a/include/linux/percpu-rwsem.h
+++ b/include/linux/percpu-rwsem.h
@@ -17,14 +17,18 @@ struct percpu_rw_semaphore {
        int                     readers_block;
 };
 
-#define DEFINE_STATIC_PERCPU_RWSEM(name)                               \
+#define __DEFINE_PERCPU_RWSEM(name, is_static)                         \
 static DEFINE_PER_CPU(unsigned int, __percpu_rwsem_rc_##name);         \
-static struct percpu_rw_semaphore name = {                             \
+is_static struct percpu_rw_semaphore name = {                          \
        .rss = __RCU_SYNC_INITIALIZER(name.rss),                        \
        .read_count = &__percpu_rwsem_rc_##name,                        \
        .rw_sem = __RWSEM_INITIALIZER(name.rw_sem),                     \
        .writer = __RCUWAIT_INITIALIZER(name.writer),                   \
 }
+#define DEFINE_PERCPU_RWSEM(name)              \
+       __DEFINE_PERCPU_RWSEM(name, /* not static */)
+#define DEFINE_STATIC_PERCPU_RWSEM(name)       \
+       __DEFINE_PERCPU_RWSEM(name, static)
 
 extern int __percpu_down_read(struct percpu_rw_semaphore *, int);
 extern void __percpu_up_read(struct percpu_rw_semaphore *);

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 217cec4..b112e93 100644 (file)
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -101,7 +101,7 @@ static DEFINE_SPINLOCK(cgroup_idr_lock);
  */
 static DEFINE_SPINLOCK(cgroup_file_kn_lock);
 
-struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
+DEFINE_PERCPU_RWSEM(cgroup_threadgroup_rwsem);
 
 #define cgroup_assert_mutex_or_rcu_locked()                            \
        RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&                       \
@@ -5616,7 +5616,6 @@ int __init cgroup_init(void)
        int ssid;
 
        BUILD_BUG_ON(CGROUP_SUBSYS_COUNT > 16);
-       BUG_ON(percpu_init_rwsem(&cgroup_threadgroup_rwsem));
        BUG_ON(cgroup_init_cftypes(NULL, cgroup_base_files));
        BUG_ON(cgroup_init_cftypes(NULL, cgroup1_base_files));