rcu: Introduce force_rcu notifier

[mirror_qemu.git] / include / qemu / rcu.h

diff --git a/include/qemu/rcu.h b/include/qemu/rcu.h
index 0e375ebe13e3f213ab1131dc27775257f2182a1b..e69efbd47f704fb5171e2d8458b00f1174239f42 100644 (file)
--- a/include/qemu/rcu.h
+++ b/include/qemu/rcu.h
@@ -27,6 +27,7 @@
 #include "qemu/thread.h"
 #include "qemu/queue.h"
 #include "qemu/atomic.h"
+#include "qemu/notify.h"
 #include "qemu/sys_membarrier.h"
 
 #ifdef __cplusplus
@@ -66,6 +67,13 @@ struct rcu_reader_data {
 
     /* Data used for registry, protected by rcu_registry_lock */
     QLIST_ENTRY(rcu_reader_data) node;
+
+    /*
+     * NotifierList used to force an RCU grace period.  Accessed under
+     * rcu_registry_lock.  Note that the notifier is called _outside_
+     * the thread!
+     */
+    NotifierList force_rcu;
 };
 
 extern __thread struct rcu_reader_data rcu_reader;
@@ -79,8 +87,8 @@ static inline void rcu_read_lock(void)
         return;
     }
 
-    ctr = atomic_read(&rcu_gp_ctr);
-    atomic_set(&p_rcu_reader->ctr, ctr);
+    ctr = qatomic_read(&rcu_gp_ctr);
+    qatomic_set(&p_rcu_reader->ctr, ctr);
 
     /* Write p_rcu_reader->ctr before reading RCU-protected pointers.  */
     smp_mb_placeholder();
@@ -100,12 +108,12 @@ static inline void rcu_read_unlock(void)
      * smp_mb_placeholder(), this ensures writes to p_rcu_reader->ctr
      * are sequentially consistent.
      */
-    atomic_store_release(&p_rcu_reader->ctr, 0);
+    qatomic_store_release(&p_rcu_reader->ctr, 0);
 
     /* Write p_rcu_reader->ctr before reading p_rcu_reader->waiting.  */
     smp_mb_placeholder();
-    if (unlikely(atomic_read(&p_rcu_reader->waiting))) {
-        atomic_set(&p_rcu_reader->waiting, false);
+    if (unlikely(qatomic_read(&p_rcu_reader->waiting))) {
+        qatomic_set(&p_rcu_reader->waiting, false);
         qemu_event_set(&rcu_gp_event);
     }
 }
@@ -180,6 +188,13 @@ G_DEFINE_AUTOPTR_CLEANUP_FUNC(RCUReadAuto, rcu_read_auto_unlock)
 #define RCU_READ_LOCK_GUARD() \
     g_autoptr(RCUReadAuto) _rcu_read_auto __attribute__((unused)) = rcu_read_auto_lock()
 
+/*
+ * Force-RCU notifiers tell readers that they should exit their
+ * read-side critical section.
+ */
+void rcu_add_force_rcu_notifier(Notifier *n);
+void rcu_remove_force_rcu_notifier(Notifier *n);
+
 #ifdef __cplusplus
 }
 #endif