1 files changed, 37 insertions, 23 deletions

diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 55a5c52cbb25..04f4121a23ae 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -16,8 +16,10 @@
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  *
  * Copyright (C) IBM Corporation, 2006
+ * Copyright (C) Fujitsu, 2012
  *
  * Author: Paul McKenney <paulmck@us.ibm.com>
+ *         Lai Jiangshan <laijs@cn.fujitsu.com>
  *
  * For detailed explanation of Read-Copy Update mechanism see -
  *              Documentation/RCU/ *.txt
@@ -40,6 +42,8 @@ struct rcu_batch {
         struct rcu_head *head, **tail;
 };
 
+#define RCU_BATCH_INIT(name) { NULL, &(name.head) }
+
 struct srcu_struct {
         unsigned completed;
         struct srcu_struct_array __percpu *per_cpu_ref;
@@ -70,12 +74,42 @@ int __init_srcu_struct(struct srcu_struct *sp, const char *name,
         __init_srcu_struct((sp), #sp, &__srcu_key); \
 })
 
+#define __SRCU_DEP_MAP_INIT(srcu_name)  .dep_map = { .name = #srcu_name },
 #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
 int init_srcu_struct(struct srcu_struct *sp);
 
+#define __SRCU_DEP_MAP_INIT(srcu_name)
 #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
+void process_srcu(struct work_struct *work);
+
+#define __SRCU_STRUCT_INIT(name)                                        \
+        {                                                               \
+                .completed = -300,                                      \
+                .per_cpu_ref = &name##_srcu_array,                      \
+                .queue_lock = __SPIN_LOCK_UNLOCKED(name.queue_lock),    \
+                .running = false,                                       \
+                .batch_queue = RCU_BATCH_INIT(name.batch_queue),        \
+                .batch_check0 = RCU_BATCH_INIT(name.batch_check0),      \
+                .batch_check1 = RCU_BATCH_INIT(name.batch_check1),      \
+                .batch_done = RCU_BATCH_INIT(name.batch_done),          \
+                .work = __DELAYED_WORK_INITIALIZER(name.work, process_srcu, 0),\
+                __SRCU_DEP_MAP_INIT(name)                               \
+        }
+
+/*
+ * define and init a srcu struct at build time.
+ * dont't call init_srcu_struct() nor cleanup_srcu_struct() on it.
+ */
+#define DEFINE_SRCU(name)                                               \
+        static DEFINE_PER_CPU(struct srcu_struct_array, name##_srcu_array);\
+        struct srcu_struct name = __SRCU_STRUCT_INIT(name);
+
+#define DEFINE_STATIC_SRCU(name)                                        \
+        static DEFINE_PER_CPU(struct srcu_struct_array, name##_srcu_array);\
+        static struct srcu_struct name = __SRCU_STRUCT_INIT(name);
+
 /**
  * call_srcu() - Queue a callback for invocation after an SRCU grace period
  * @sp: srcu_struct in queue the callback
@@ -117,30 +151,14 @@ void srcu_barrier(struct srcu_struct *sp);
  * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot
  * and while lockdep is disabled.
  *
- * Note that if the CPU is in the idle loop from an RCU point of view
- * (ie: that we are in the section between rcu_idle_enter() and
- * rcu_idle_exit()) then srcu_read_lock_held() returns false even if
- * the CPU did an srcu_read_lock().  The reason for this is that RCU
- * ignores CPUs that are in such a section, considering these as in
- * extended quiescent state, so such a CPU is effectively never in an
- * RCU read-side critical section regardless of what RCU primitives it
- * invokes.  This state of affairs is required --- we need to keep an
- * RCU-free window in idle where the CPU may possibly enter into low
- * power mode. This way we can notice an extended quiescent state to
- * other CPUs that started a grace period. Otherwise we would delay any
- * grace period as long as we run in the idle task.
- *
- * Similarly, we avoid claiming an SRCU read lock held if the current
- * CPU is offline.
+ * Note that SRCU is based on its own statemachine and it doesn't
+ * relies on normal RCU, it can be called from the CPU which
+ * is in the idle loop from an RCU point of view or offline.
  */
 static inline int srcu_read_lock_held(struct srcu_struct *sp)
 {
         if (!debug_lockdep_rcu_enabled())
                 return 1;
-        if (rcu_is_cpu_idle())
-                return 0;
-        if (!rcu_lockdep_current_cpu_online())
-                return 0;
         return lock_is_held(&sp->dep_map);
 }
 
@@ -202,8 +220,6 @@ static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
         int retval = __srcu_read_lock(sp);
 
         rcu_lock_acquire(&(sp)->dep_map);
-        rcu_lockdep_assert(!rcu_is_cpu_idle(),
-                           "srcu_read_lock() used illegally while idle");
         return retval;
 }
 
@@ -217,8 +233,6 @@ static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
 static inline void srcu_read_unlock(struct srcu_struct *sp, int idx)
         __releases(sp)
 {
-        rcu_lockdep_assert(!rcu_is_cpu_idle(),
-                           "srcu_read_unlock() used illegally while idle");
         rcu_lock_release(&(sp)->dep_map);
         __srcu_read_unlock(sp, idx);
 }