From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50485) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ejOTe-00019J-Ni for qemu-devel@nongnu.org; Wed, 07 Feb 2018 07:05:36 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ejOTa-0004Tf-2x for qemu-devel@nongnu.org; Wed, 07 Feb 2018 07:05:26 -0500 Received: from mail.ispras.ru ([83.149.199.45]:47640) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ejOTZ-0004TM-Qu for qemu-devel@nongnu.org; Wed, 07 Feb 2018 07:05:22 -0500 From: Pavel Dovgalyuk Date: Wed, 07 Feb 2018 15:05:23 +0300 Message-ID: <20180207120523.5389.91342.stgit@pasha-VirtualBox> In-Reply-To: <20180207120353.5389.54531.stgit@pasha-VirtualBox> References: <20180207120353.5389.54531.stgit@pasha-VirtualBox> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] [RFC PATCH v6 16/20] replay: avoid recursive call of checkpoints List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, peter.maydell@linaro.org, war2jordan@live.com, boost.lists@gmail.com, quintela@redhat.com, ciro.santilli@gmail.com, jasowang@redhat.com, mst@redhat.com, zuban32s@gmail.com, maria.klimushenkova@ispras.ru, dovgaluk@ispras.ru, kraxel@redhat.com, pavel.dovgaluk@ispras.ru, thomas.dullien@googlemail.com, pbonzini@redhat.com, alex.bennee@linaro.org This patch adds a flag which denies recursive call of replay_checkpoint function. Checkpoints may be accompanied by the hardware events. When event is processed, virtual device may invoke timer modification functions that also invoke the checkpoint function. This leads to infinite loop. Signed-off-by: Pavel Dovgalyuk --- replay/replay.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/replay/replay.c b/replay/replay.c index 585c5de..c676dd4 100644 --- a/replay/replay.c +++ b/replay/replay.c @@ -176,13 +176,24 @@ void replay_shutdown_request(ShutdownCause cause) bool replay_checkpoint(ReplayCheckpoint checkpoint) { bool res = false; + static bool in_checkpoint; assert(EVENT_CHECKPOINT + checkpoint <= EVENT_CHECKPOINT_LAST); - replay_save_instructions(); if (!replay_file) { return true; } + if (in_checkpoint) { + /* If we are already in checkpoint, then there is no need + for additional synchronization. + Recursion occurs when HW event modifies timers. + Timer modification may invoke the checkpoint and + proceed to recursion. */ + return true; + } + in_checkpoint = true; + + replay_save_instructions(); if (replay_mode == REPLAY_MODE_PLAY) { g_assert(replay_mutex_locked()); @@ -204,6 +215,7 @@ bool replay_checkpoint(ReplayCheckpoint checkpoint) res = true; } out: + in_checkpoint = false; return res; }