Add qemu 2.4.0

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

diff --git a/qemu/include/qemu/rcu.h b/qemu/include/qemu/rcu.h
new file mode 100644 (file)
index 0000000..7df1e86
--- /dev/null
+++ b/qemu/include/qemu/rcu.h
@@ -0,0 +1,156 @@
+#ifndef QEMU_RCU_H
+#define QEMU_RCU_H
+
+/*
+ * urcu-mb.h
+ *
+ * Userspace RCU header with explicit memory barrier.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * IBM's contributions to this file may be relicensed under LGPLv2 or later.
+ */
+
+#include <stdlib.h>
+#include <assert.h>
+#include <limits.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <glib.h>
+
+#include "qemu/compiler.h"
+#include "qemu/thread.h"
+#include "qemu/queue.h"
+#include "qemu/atomic.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * Important !
+ *
+ * Each thread containing read-side critical sections must be registered
+ * with rcu_register_thread() before calling rcu_read_lock().
+ * rcu_unregister_thread() should be called before the thread exits.
+ */
+
+#ifdef DEBUG_RCU
+#define rcu_assert(args...)    assert(args)
+#else
+#define rcu_assert(args...)
+#endif
+
+/*
+ * Global quiescent period counter with low-order bits unused.
+ * Using a int rather than a char to eliminate false register dependencies
+ * causing stalls on some architectures.
+ */
+extern unsigned long rcu_gp_ctr;
+
+extern QemuEvent rcu_gp_event;
+
+struct rcu_reader_data {
+    /* Data used by both reader and synchronize_rcu() */
+    unsigned long ctr;
+    bool waiting;
+
+    /* Data used by reader only */
+    unsigned depth;
+
+    /* Data used for registry, protected by rcu_gp_lock */
+    QLIST_ENTRY(rcu_reader_data) node;
+};
+
+extern __thread struct rcu_reader_data rcu_reader;
+
+static inline void rcu_read_lock(void)
+{
+    struct rcu_reader_data *p_rcu_reader = &rcu_reader;
+    unsigned ctr;
+
+    if (p_rcu_reader->depth++ > 0) {
+        return;
+    }
+
+    ctr = atomic_read(&rcu_gp_ctr);
+    atomic_xchg(&p_rcu_reader->ctr, ctr);
+    if (atomic_read(&p_rcu_reader->waiting)) {
+        atomic_set(&p_rcu_reader->waiting, false);
+        qemu_event_set(&rcu_gp_event);
+    }
+}
+
+static inline void rcu_read_unlock(void)
+{
+    struct rcu_reader_data *p_rcu_reader = &rcu_reader;
+
+    assert(p_rcu_reader->depth != 0);
+    if (--p_rcu_reader->depth > 0) {
+        return;
+    }
+
+    atomic_xchg(&p_rcu_reader->ctr, 0);
+    if (atomic_read(&p_rcu_reader->waiting)) {
+        atomic_set(&p_rcu_reader->waiting, false);
+        qemu_event_set(&rcu_gp_event);
+    }
+}
+
+extern void synchronize_rcu(void);
+
+/*
+ * Reader thread registration.
+ */
+extern void rcu_register_thread(void);
+extern void rcu_unregister_thread(void);
+extern void rcu_after_fork(void);
+
+struct rcu_head;
+typedef void RCUCBFunc(struct rcu_head *head);
+
+struct rcu_head {
+    struct rcu_head *next;
+    RCUCBFunc *func;
+};
+
+extern void call_rcu1(struct rcu_head *head, RCUCBFunc *func);
+
+/* The operands of the minus operator must have the same type,
+ * which must be the one that we specify in the cast.
+ */
+#define call_rcu(head, func, field)                                      \
+    call_rcu1(({                                                         \
+         char __attribute__((unused))                                    \
+            offset_must_be_zero[-offsetof(typeof(*(head)), field)],      \
+            func_type_invalid = (func) - (void (*)(typeof(head)))(func); \
+         &(head)->field;                                                 \
+      }),                                                                \
+      (RCUCBFunc *)(func))
+
+#define g_free_rcu(obj, field) \
+    call_rcu1(({                                                         \
+        char __attribute__((unused))                                     \
+            offset_must_be_zero[-offsetof(typeof(*(obj)), field)];       \
+        &(obj)->field;                                                   \
+      }),                                                                \
+      (RCUCBFunc *)g_free);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* QEMU_RCU_H */