91 lines
4.4 KiB
Diff
91 lines
4.4 KiB
Diff
|
From 05630592885c6c82ba83e197626e773b0d93d608 Mon Sep 17 00:00:00 2001
|
||
|
|
From: Jon Maloy <jmaloy@redhat.com>
|
||
|
|
Date: Fri, 18 Nov 2022 20:26:54 -0500
|
||
|
|
Subject: [PATCH 1/6] ui/vnc.c: Fixed a deadlock bug.
|
||
|
|
MIME-Version: 1.0
|
||
|
|
Content-Type: text/plain; charset=UTF-8
|
||
|
|
Content-Transfer-Encoding: 8bit
|
||
|
|
|
||
|
|
RH-Author: Jon Maloy <jmaloy@redhat.com>
|
||
|
|
RH-MergeRequest: 237: ui/vnc.c: Fixed a deadlock bug.
|
||
|
|
RH-Bugzilla: 2148504
|
||
|
|
RH-Acked-by: Gerd Hoffmann <kraxel@redhat.com>
|
||
|
|
RH-Acked-by: Marc-André Lureau <marcandre.lureau@redhat.com>
|
||
|
|
RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
|
||
|
|
RH-Commit: [1/1] 0be7fc3eaa5b41e806adaf75750fee75bb33a92f (jmaloy/jons-qemu-kvm)
|
||
|
|
|
||
|
|
BZ: https://bugzilla.redhat.com/show_bug.cgi?id=2148504
|
||
|
|
Upstream: Merged
|
||
|
|
|
||
|
|
commit 1dbbe6f172810026c51dc84ed927a3cc23017949
|
||
|
|
Author: Rao Lei <lei.rao@intel.com>
|
||
|
|
Date: Wed Jan 5 10:08:08 2022 +0800
|
||
|
|
|
||
|
|
ui/vnc.c: Fixed a deadlock bug.
|
||
|
|
|
||
|
|
The GDB statck is as follows:
|
||
|
|
(gdb) bt
|
||
|
|
0 __lll_lock_wait (futex=futex@entry=0x56211df20360, private=0) at lowlevellock.c:52
|
||
|
|
1 0x00007f263caf20a3 in __GI___pthread_mutex_lock (mutex=0x56211df20360) at ../nptl/pthread_mutex_lock.c:80
|
||
|
|
2 0x000056211a757364 in qemu_mutex_lock_impl (mutex=0x56211df20360, file=0x56211a804857 "../ui/vnc-jobs.h", line=60)
|
||
|
|
at ../util/qemu-thread-posix.c:80
|
||
|
|
3 0x000056211a0ef8c7 in vnc_lock_output (vs=0x56211df14200) at ../ui/vnc-jobs.h:60
|
||
|
|
4 0x000056211a0efcb7 in vnc_clipboard_send (vs=0x56211df14200, count=1, dwords=0x7ffdf1701338) at ../ui/vnc-clipboard.c:138
|
||
|
|
5 0x000056211a0f0129 in vnc_clipboard_notify (notifier=0x56211df244c8, data=0x56211dd1bbf0) at ../ui/vnc-clipboard.c:209
|
||
|
|
6 0x000056211a75dde8 in notifier_list_notify (list=0x56211afa17d0 <clipboard_notifiers>, data=0x56211dd1bbf0) at ../util/notify.c:39
|
||
|
|
7 0x000056211a0bf0e6 in qemu_clipboard_update (info=0x56211dd1bbf0) at ../ui/clipboard.c:50
|
||
|
|
8 0x000056211a0bf05d in qemu_clipboard_peer_release (peer=0x56211df244c0, selection=QEMU_CLIPBOARD_SELECTION_CLIPBOARD)
|
||
|
|
at ../ui/clipboard.c:41
|
||
|
|
9 0x000056211a0bef9b in qemu_clipboard_peer_unregister (peer=0x56211df244c0) at ../ui/clipboard.c:19
|
||
|
|
10 0x000056211a0d45f3 in vnc_disconnect_finish (vs=0x56211df14200) at ../ui/vnc.c:1358
|
||
|
|
11 0x000056211a0d4c9d in vnc_client_read (vs=0x56211df14200) at ../ui/vnc.c:1611
|
||
|
|
12 0x000056211a0d4df8 in vnc_client_io (ioc=0x56211ce70690, condition=G_IO_IN, opaque=0x56211df14200) at ../ui/vnc.c:1649
|
||
|
|
13 0x000056211a5b976c in qio_channel_fd_source_dispatch
|
||
|
|
(source=0x56211ce50a00, callback=0x56211a0d4d71 <vnc_client_io>, user_data=0x56211df14200) at ../io/channel-watch.c:84
|
||
|
|
14 0x00007f263ccede8e in g_main_context_dispatch () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
|
||
|
|
15 0x000056211a77d4a1 in glib_pollfds_poll () at ../util/main-loop.c:232
|
||
|
|
16 0x000056211a77d51f in os_host_main_loop_wait (timeout=958545) at ../util/main-loop.c:255
|
||
|
|
17 0x000056211a77d630 in main_loop_wait (nonblocking=0) at ../util/main-loop.c:531
|
||
|
|
18 0x000056211a45bc8e in qemu_main_loop () at ../softmmu/runstate.c:726
|
||
|
|
19 0x000056211a0b45fa in main (argc=69, argv=0x7ffdf1701778, envp=0x7ffdf17019a8) at ../softmmu/main.c:50
|
||
|
|
|
||
|
|
From the call trace, we can see it is a deadlock bug.
|
||
|
|
vnc_disconnect_finish will acquire the output_mutex.
|
||
|
|
But, the output_mutex will be acquired again in vnc_clipboard_send.
|
||
|
|
Repeated locking will cause deadlock. So, I move
|
||
|
|
qemu_clipboard_peer_unregister() behind vnc_unlock_output();
|
||
|
|
Fixes: 0bf41cab93e ("ui/vnc: clipboard support")
|
||
|
|
Signed-off-by: Lei Rao <lei.rao@intel.com>
|
||
|
|
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
|
||
|
|
Message-Id: <20220105020808.597325-1-lei.rao@intel.com>
|
||
|
|
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
|
||
|
|
|
||
|
|
(cherry picked from commit 1dbbe6f172810026c51dc84ed927a3cc23017949)
|
||
|
|
Signed-off-by: Jon Maloy <jmaloy@redhat.com>
|
||
|
|
---
|
||
|
|
ui/vnc.c | 4 ++--
|
||
|
|
1 file changed, 2 insertions(+), 2 deletions(-)
|
||
|
|
|
||
|
|
diff --git a/ui/vnc.c b/ui/vnc.c
|
||
|
|
index af02522e84..b253e85c65 100644
|
||
|
|
--- a/ui/vnc.c
|
||
|
|
+++ b/ui/vnc.c
|
||
|
|
@@ -1354,12 +1354,12 @@ void vnc_disconnect_finish(VncState *vs)
|
||
|
|
/* last client gone */
|
||
|
|
vnc_update_server_surface(vs->vd);
|
||
|
|
}
|
||
|
|
+ vnc_unlock_output(vs);
|
||
|
|
+
|
||
|
|
if (vs->cbpeer.update.notify) {
|
||
|
|
qemu_clipboard_peer_unregister(&vs->cbpeer);
|
||
|
|
}
|
||
|
|
|
||
|
|
- vnc_unlock_output(vs);
|
||
|
|
-
|
||
|
|
qemu_mutex_destroy(&vs->output_mutex);
|
||
|
|
if (vs->bh != NULL) {
|
||
|
|
qemu_bh_delete(vs->bh);
|
||
|
|
--
|
||
|
|
2.37.3
|
||
|
|
|