[Qemu-devel] [RFC PATCH v9 05/23] replay: introduce mutex to protect the replay log

[Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>]

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>
---
 replay/replay-internal.c |   27 +++++++++++++++++++++++++++
 replay/replay-internal.h |    7 +++++++
 2 files changed, 34 insertions(+), 0 deletions(-)

diff --git a/replay/replay-internal.c b/replay/replay-internal.c
index e905de8..ce7a1d8 100755
--- a/replay/replay-internal.c
+++ b/replay/replay-internal.c
@@ -15,6 +15,13 @@
 unsigned int replay_data_kind = -1;
 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;
 
@@ -141,3 +148,23 @@ void replay_fetch_data_kind(void)
         }
     }
 }
+
+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);
+}
diff --git a/replay/replay-internal.h b/replay/replay-internal.h
index d1b7575..d92410e 100755
--- a/replay/replay-internal.h
+++ b/replay/replay-internal.h
@@ -34,6 +34,13 @@ int64_t replay_get_qword(void);
 void replay_get_array(uint8_t *buf, size_t *size);
 void replay_get_array_alloc(uint8_t **buf, size_t *size);
 
+/* Mutex functions for protecting replay log file */
+
+void replay_mutex_init(void);
+void replay_mutex_destroy(void);
+void replay_mutex_lock(void);
+void replay_mutex_unlock(void);
+
 /*! Checks error status of the file. */
 void replay_check_error(void);