[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[PULL 08/10] monitor: Fix order in monitor_cleanup()
From: |
Kevin Wolf |
Subject: |
[PULL 08/10] monitor: Fix order in monitor_cleanup() |
Date: |
Thu, 15 Oct 2020 16:49:50 +0200 |
We can only destroy Monitor objects after we're sure that they are not
in use by the dispatcher coroutine any more. This fixes crashes like the
following where we tried to destroy a monitor mutex while the dispatcher
coroutine still holds it:
(gdb) bt
#0 0x00007fe541cf4bc5 in raise () at /lib64/libc.so.6
#1 0x00007fe541cdd8a4 in abort () at /lib64/libc.so.6
#2 0x000055c24e965327 in error_exit (err=16, msg=0x55c24eead3a0 <__func__.33>
"qemu_mutex_destroy") at ../util/qemu-thread-posix.c:37
#3 0x000055c24e9654c3 in qemu_mutex_destroy (mutex=0x55c25133e0f0) at
../util/qemu-thread-posix.c:70
#4 0x000055c24e7cfaf1 in monitor_data_destroy_qmp (mon=0x55c25133dfd0) at
../monitor/qmp.c:439
#5 0x000055c24e7d23bc in monitor_data_destroy (mon=0x55c25133dfd0) at
../monitor/monitor.c:615
#6 0x000055c24e7d253a in monitor_cleanup () at ../monitor/monitor.c:644
#7 0x000055c24e6cb002 in qemu_cleanup () at ../softmmu/vl.c:4549
#8 0x000055c24e0d259b in main (argc=24, argv=0x7ffff66b0d58,
envp=0x7ffff66b0e20) at ../softmmu/main.c:51
Reported-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20201013125027.41003-1-kwolf@redhat.com>
Tested-by: Ben Widawsky <ben.widawsky@intel.com>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
monitor/monitor.c | 33 +++++++++++++++++----------------
1 file changed, 17 insertions(+), 16 deletions(-)
diff --git a/monitor/monitor.c b/monitor/monitor.c
index ceffe1a83b..84222cd130 100644
--- a/monitor/monitor.c
+++ b/monitor/monitor.c
@@ -632,23 +632,9 @@ void monitor_cleanup(void)
iothread_stop(mon_iothread);
}
- /* Flush output buffers and destroy monitors */
- qemu_mutex_lock(&monitor_lock);
- monitor_destroyed = true;
- while (!QTAILQ_EMPTY(&mon_list)) {
- Monitor *mon = QTAILQ_FIRST(&mon_list);
- QTAILQ_REMOVE(&mon_list, mon, entry);
- /* Permit QAPI event emission from character frontend release */
- qemu_mutex_unlock(&monitor_lock);
- monitor_flush(mon);
- monitor_data_destroy(mon);
- qemu_mutex_lock(&monitor_lock);
- g_free(mon);
- }
- qemu_mutex_unlock(&monitor_lock);
-
/*
- * The dispatcher needs to stop before destroying the I/O thread.
+ * The dispatcher needs to stop before destroying the monitor and
+ * the I/O thread.
*
* We need to poll both qemu_aio_context and iohandler_ctx to make
* sure that the dispatcher coroutine keeps making progress and
@@ -665,6 +651,21 @@ void monitor_cleanup(void)
(aio_poll(iohandler_get_aio_context(), false),
qatomic_mb_read(&qmp_dispatcher_co_busy)));
+ /* Flush output buffers and destroy monitors */
+ qemu_mutex_lock(&monitor_lock);
+ monitor_destroyed = true;
+ while (!QTAILQ_EMPTY(&mon_list)) {
+ Monitor *mon = QTAILQ_FIRST(&mon_list);
+ QTAILQ_REMOVE(&mon_list, mon, entry);
+ /* Permit QAPI event emission from character frontend release */
+ qemu_mutex_unlock(&monitor_lock);
+ monitor_flush(mon);
+ monitor_data_destroy(mon);
+ qemu_mutex_lock(&monitor_lock);
+ g_free(mon);
+ }
+ qemu_mutex_unlock(&monitor_lock);
+
if (mon_iothread) {
iothread_destroy(mon_iothread);
mon_iothread = NULL;
--
2.28.0
- [PULL 00/10] Block layer patches, Kevin Wolf, 2020/10/15
- [PULL 01/10] keyval: Fix and clarify grammar, Kevin Wolf, 2020/10/15
- [PULL 02/10] test-keyval: Demonstrate misparse of ', ' with implied key, Kevin Wolf, 2020/10/15
- [PULL 03/10] keyval: Fix parsing of ',' in value of implied key, Kevin Wolf, 2020/10/15
- [PULL 05/10] qom: Factor out helpers from user_creatable_print_help(), Kevin Wolf, 2020/10/15
- [PULL 06/10] qom: Add user_creatable_print_help_from_qdict(), Kevin Wolf, 2020/10/15
- [PULL 04/10] keyval: Parse help options, Kevin Wolf, 2020/10/15
- [PULL 09/10] block: drop moderated sheepdog mailing list from MAINTAINERS file, Kevin Wolf, 2020/10/15
- [PULL 07/10] qemu-storage-daemon: Remove QemuOpts from --object parser, Kevin Wolf, 2020/10/15
- [PULL 08/10] monitor: Fix order in monitor_cleanup(),
Kevin Wolf <=
- [PULL 10/10] block: deprecate the sheepdog block driver, Kevin Wolf, 2020/10/15
- Re: [PULL 00/10] Block layer patches, Peter Maydell, 2020/10/16