replay: introduce mutex to protect the replay log

This mutex will protect read/write operations for replay log.
Using mutex is necessary because most of the events consist of
several fields stored in the log. The mutex will help to avoid races.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Message-Id: <20150917162348.8676.8628.stgit@PASHA-ISP.def.inno>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/replay/replay-internal.c b/replay/replay-internal.c
index 04efeee920..efae672dfa 100644
--- a/replay/replay-internal.c
+++ b/replay/replay-internal.c
@@ -17,6 +17,13 @@
 unsigned int replay_data_kind = -1;
 static unsigned int replay_has_unread_data;
 
+/* Mutex to protect reading and writing events to the log.
+   replay_data_kind and replay_has_unread_data are also protected
+   by this mutex.
+   It also protects replay events queue which stores events to be
+   written or read to the log. */
+static QemuMutex lock;
+
 /* File for replay writing */
 FILE *replay_file;
 
@@ -153,3 +160,23 @@ void replay_finish_event(void)
     replay_has_unread_data = 0;
     replay_fetch_data_kind();
 }
+
+void replay_mutex_init(void)
+{
+    qemu_mutex_init(&lock);
+}
+
+void replay_mutex_destroy(void)
+{
+    qemu_mutex_destroy(&lock);
+}
+
+void replay_mutex_lock(void)
+{
+    qemu_mutex_lock(&lock);
+}
+
+void replay_mutex_unlock(void)
+{
+    qemu_mutex_unlock(&lock);
+}