@@ -46,6 +46,20 @@ extern ReplayMode replay_mode;
/* Name of the initial VM snapshot */
extern char *replay_snapshot;
+/* Replay locking
+ *
+ * The locks are needed to protect the shared structures and log file
+ * when doing record/replay. They also are the main sync-point between
+ * the main-loop thread and the vCPU thread. This was a role
+ * previously filled by the BQL which has been busy trying to reduce
+ * its impact across the code. This ensures blocks of events stay
+ * sequential and reproducible.
+ */
+
+void replay_mutex_lock(void);
+void replay_mutex_unlock(void);
+bool replay_mutex_locked(void);
+
/* Replay process control functions */
/*! Enables recording or saving event log with specified parameters */
@@ -181,7 +181,7 @@ void replay_mutex_destroy(void)
static __thread bool replay_locked;
-static bool replay_mutex_locked(void)
+bool replay_mutex_locked(void)
{
return replay_locked;
}
@@ -204,7 +204,7 @@ void replay_mutex_unlock(void)
void replay_save_instructions(void)
{
if (replay_file && replay_mode == REPLAY_MODE_RECORD) {
- replay_mutex_lock();
+ g_assert(replay_mutex_locked());
int diff = (int)(replay_get_current_step() - replay_state.current_step);
/* Time can only go forward */
@@ -215,6 +215,5 @@ void replay_save_instructions(void)
replay_put_dword(diff);
replay_state.current_step += diff;
}
- replay_mutex_unlock();
}
}
@@ -97,12 +97,11 @@ 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 */
+/* Mutex functions for protecting replay log file and ensuring
+ * synchronisation between vCPU and main-loop threads. */
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);
@@ -72,3 +72,18 @@ uint64_t blkreplay_next_id(void)
{
return 0;
}
+
+void replay_mutex_lock(void)
+{
+ abort();
+}
+
+void replay_mutex_unlock(void)
+{
+ abort();
+}
+
+bool replay_mutex_locked(void)
+{
+ return false;
+}
The replay_mutex_lock/unlock/locked functions are now going to be used for ensuring lock-step behaviour between the two threads. Make them public API functions and also provide stubs for non-QEMU builds on common paths. Signed-off-by: Alex Bennée <alex.bennee@linaro.org> --- include/sysemu/replay.h | 14 ++++++++++++++ replay/replay-internal.c | 5 ++--- replay/replay-internal.h | 5 ++--- stubs/replay.c | 15 +++++++++++++++ 4 files changed, 33 insertions(+), 6 deletions(-) -- 2.11.0