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X-Received-From: 2a00:1450:400c:c09::230 Subject: [Qemu-devel] [RFC PATCH v1 5/9] replay: make locking visible outside replay code X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: cota@braap.org, =?utf-8?q?Alex_Benn=C3=A9e?= , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+patch=linaro.org@nongnu.org Sender: "Qemu-devel" 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 --- 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 diff --git a/include/sysemu/replay.h b/include/sysemu/replay.h index f1c0712795..08bffa2dc2 100644 --- a/include/sysemu/replay.h +++ b/include/sysemu/replay.h @@ -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 */ diff --git a/replay/replay-internal.c b/replay/replay-internal.c index 157c863e25..e6b2fdb6c1 100644 --- a/replay/replay-internal.c +++ b/replay/replay-internal.c @@ -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(); } } diff --git a/replay/replay-internal.h b/replay/replay-internal.h index ed66ed803c..b0cf78f16f 100644 --- a/replay/replay-internal.h +++ b/replay/replay-internal.h @@ -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); diff --git a/stubs/replay.c b/stubs/replay.c index 9c8aa48c9c..39c5746043 100644 --- a/stubs/replay.c +++ b/stubs/replay.c @@ -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; +}