* [PATCH 2/3] migration/multifd: fix destroyed mutex access in terminating multifd threads
[not found] <20191023034738.10309-1-cenjiahui@huawei.com>
@ 2019-10-23 3:47 ` cenjiahui
2020-01-09 10:08 ` Juan Quintela
0 siblings, 1 reply; 2+ messages in thread
From: cenjiahui @ 2019-10-23 3:47 UTC (permalink / raw)
To: quintela, dgilbert; +Cc: fangying1, Jiahui Cen, qemu-devel, peterx, zhouyibo3
From: Jiahui Cen <cenjiahui@huawei.com>
One multifd will lock all the other multifds' IOChannel mutex to inform them
to quit by setting p->quit or shutting down p->c. In this senario, if some
multifds had already been terminated and multifd_load_cleanup/multifd_save_cleanup
had destroyed their mutex, it could cause destroyed mutex access when trying
lock their mutex.
Here is the coredump stack:
#0 0x00007f81a2794437 in raise () from /usr/lib64/libc.so.6
#1 0x00007f81a2795b28 in abort () from /usr/lib64/libc.so.6
#2 0x00007f81a278d1b6 in __assert_fail_base () from /usr/lib64/libc.so.6
#3 0x00007f81a278d262 in __assert_fail () from /usr/lib64/libc.so.6
#4 0x000055eb1bfadbd3 in qemu_mutex_lock_impl (mutex=0x55eb1e2d1988, file=<optimized out>, line=<optimized out>) at util/qemu-thread-posix.c:64
#5 0x000055eb1bb4564a in multifd_send_terminate_threads (err=<optimized out>) at migration/ram.c:1015
#6 0x000055eb1bb4bb7f in multifd_send_thread (opaque=0x55eb1e2d19f8) at migration/ram.c:1171
#7 0x000055eb1bfad628 in qemu_thread_start (args=0x55eb1e170450) at util/qemu-thread-posix.c:502
#8 0x00007f81a2b36df5 in start_thread () from /usr/lib64/libpthread.so.0
#9 0x00007f81a286048d in clone () from /usr/lib64/libc.so.6
To fix it up, let's destroy the mutex after all the other multifd threads had
been terminated.
Signed-off-by: Jiahui Cen <cenjiahui@huawei.com>
Signed-off-by: Ying Fang <fangying1@huawei.com>
---
migration/ram.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/migration/ram.c b/migration/ram.c
index dc63692..24a8906 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1032,6 +1032,10 @@ void multifd_save_cleanup(void)
if (p->running) {
qemu_thread_join(&p->thread);
}
+ }
+ for (i = 0; i < migrate_multifd_channels(); i++) {
+ MultiFDSendParams *p = &multifd_send_state->params[i];
+
socket_send_channel_destroy(p->c);
p->c = NULL;
qemu_mutex_destroy(&p->mutex);
@@ -1308,6 +1312,10 @@ int multifd_load_cleanup(Error **errp)
qemu_sem_post(&p->sem_sync);
qemu_thread_join(&p->thread);
}
+ }
+ for (i = 0; i < migrate_multifd_channels(); i++) {
+ MultiFDRecvParams *p = &multifd_recv_state->params[i];
+
object_unref(OBJECT(p->c));
p->c = NULL;
qemu_mutex_destroy(&p->mutex);
--
1.8.3.1
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