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[Qemu-devel] [PATCH v12 05/25] replay: don't drain/flush bdrv queue whil
From: |
Pavel Dovgalyuk |
Subject: |
[Qemu-devel] [PATCH v12 05/25] replay: don't drain/flush bdrv queue while RR is working |
Date: |
Tue, 05 Feb 2019 11:20:10 +0300 |
User-agent: |
StGit/0.17.1-dirty |
In record/replay mode bdrv queue is controlled by replay mechanism.
It does not allow saving or loading the snapshots
when bdrv queue is not empty. Stopping the VM is not blocked by nonempty
queue, but flushing the queue is still impossible there,
because it may cause deadlocks in replay mode.
This patch disables bdrv_drain_all and bdrv_flush_all in
record/replay mode.
Stopping the machine when the IO requests are not finished is needed
for the debugging. E.g., breakpoint may be set at the specified step,
and forcing the IO requests to finish may break the determinism
of the execution.
Signed-off-by: Pavel Dovgalyuk <address@hidden>
---
block/io.c | 28 ++++++++++++++++++++++++++++
cpus.c | 2 --
2 files changed, 28 insertions(+), 2 deletions(-)
diff --git a/block/io.c b/block/io.c
index 213ca03d8d..c25864a8ee 100644
--- a/block/io.c
+++ b/block/io.c
@@ -32,6 +32,7 @@
#include "qemu/cutils.h"
#include "qapi/error.h"
#include "qemu/error-report.h"
+#include "sysemu/replay.h"
#define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress
*/
@@ -538,6 +539,15 @@ void bdrv_drain_all_begin(void)
return;
}
+ /*
+ * bdrv queue is managed by record/replay,
+ * waiting for finishing the I/O requests may
+ * be infinite
+ */
+ if (replay_events_enabled()) {
+ return;
+ }
+
/* AIO_WAIT_WHILE() with a NULL context can only be called from the main
* loop AioContext, so make sure we're in the main context. */
assert(qemu_get_current_aio_context() == qemu_get_aio_context());
@@ -566,6 +576,15 @@ void bdrv_drain_all_end(void)
{
BlockDriverState *bs = NULL;
+ /*
+ * bdrv queue is managed by record/replay,
+ * waiting for finishing the I/O requests may
+ * be endless
+ */
+ if (replay_events_enabled()) {
+ return;
+ }
+
while ((bs = bdrv_next_all_states(bs))) {
AioContext *aio_context = bdrv_get_aio_context(bs);
@@ -1998,6 +2017,15 @@ int bdrv_flush_all(void)
BlockDriverState *bs = NULL;
int result = 0;
+ /*
+ * bdrv queue is managed by record/replay,
+ * creating new flush request for stopping
+ * the VM may break the determinism
+ */
+ if (replay_events_enabled()) {
+ return result;
+ }
+
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
AioContext *aio_context = bdrv_get_aio_context(bs);
int ret;
diff --git a/cpus.c b/cpus.c
index b09b702712..aa33fb15b3 100644
--- a/cpus.c
+++ b/cpus.c
@@ -1078,7 +1078,6 @@ static int do_vm_stop(RunState state, bool send_stop)
}
bdrv_drain_all();
- replay_disable_events();
ret = bdrv_flush_all();
return ret;
@@ -2149,7 +2148,6 @@ int vm_prepare_start(void)
/* We are sending this now, but the CPUs will be resumed shortly later */
qapi_event_send_resume();
- replay_enable_events();
cpu_enable_ticks();
runstate_set(RUN_STATE_RUNNING);
vm_state_notify(1, RUN_STATE_RUNNING);
- [Qemu-devel] [PATCH v12 00/25] Fixing record/replay and adding reverse debugging, Pavel Dovgalyuk, 2019/02/05
- [Qemu-devel] [PATCH v12 01/25] replay: add missing fix for internal function, Pavel Dovgalyuk, 2019/02/05
- [Qemu-devel] [PATCH v12 02/25] block: implement bdrv_snapshot_goto for blkreplay, Pavel Dovgalyuk, 2019/02/05
- [Qemu-devel] [PATCH v12 03/25] replay: disable default snapshot for record/replay, Pavel Dovgalyuk, 2019/02/05
- [Qemu-devel] [PATCH v12 04/25] replay: update docs for record/replay with block devices, Pavel Dovgalyuk, 2019/02/05
- [Qemu-devel] [PATCH v12 05/25] replay: don't drain/flush bdrv queue while RR is working,
Pavel Dovgalyuk <=
- [Qemu-devel] [PATCH v12 06/25] replay: finish record/replay before closing the disks, Pavel Dovgalyuk, 2019/02/05
- [Qemu-devel] [PATCH v12 07/25] qcow2: introduce icount field for snapshots, Pavel Dovgalyuk, 2019/02/05
- [Qemu-devel] [PATCH v12 08/25] migration: introduce icount field for snapshots, Pavel Dovgalyuk, 2019/02/05
- [Qemu-devel] [PATCH v12 09/25] replay: provide an accessor for rr filename, Pavel Dovgalyuk, 2019/02/05
- [Qemu-devel] [PATCH v12 10/25] qapi: introduce replay.json for record/replay-related stuff, Pavel Dovgalyuk, 2019/02/05
- [Qemu-devel] [PATCH v12 11/25] replay: introduce info hmp/qmp command, Pavel Dovgalyuk, 2019/02/05
- [Qemu-devel] [PATCH v12 12/25] replay: introduce breakpoint at the specified step, Pavel Dovgalyuk, 2019/02/05
- [Qemu-devel] [PATCH v12 13/25] replay: implement replay-seek command, Pavel Dovgalyuk, 2019/02/05
- [Qemu-devel] [PATCH v12 14/25] replay: refine replay-time module, Pavel Dovgalyuk, 2019/02/05
- [Qemu-devel] [PATCH v12 15/25] replay: flush rr queue before loading the vmstate, Pavel Dovgalyuk, 2019/02/05