On Fri, 02 Sep 2011 15:39:03 +0200 Gerd Hoffmann <kra...@redhat.com> wrote:
> Hi, > > >> After some investigation, I found out that the problem is that different > >> SPICE threads are calling monitor functions (such as > >> monitor_protocol_event()) in parallel which causes concurrent access > >> to the monitor's internal buffer outbuf[]. > > [ adding spice-list to Cc, see qemu-devel for the rest of the thread ] > > spice isn't supposed to do that. > > /me just added a assert in channel_event() and saw it trigger in display > channel disconnects. > > #0 0x0000003ceba32a45 in raise () from /lib64/libc.so.6 > #1 0x0000003ceba34225 in abort () from /lib64/libc.so.6 > #2 0x0000003ceba2b9d5 in __assert_fail () from /lib64/libc.so.6 > #3 0x0000000000503759 in channel_event (event=3, info=0x35e9340) > at /home/kraxel/projects/qemu/ui/spice-core.c:223 > #4 0x00007f9a77a9921b in reds_channel_event (s=0x35e92c0) at reds.c:400 > #5 reds_stream_free (s=0x35e92c0) at reds.c:4981 > #6 0x00007f9a77aac8b0 in red_disconnect_channel > (channel=0x7f9a24069a80) at red_worker.c:8489 > #7 0x00007f9a77ab53a8 in handle_dev_input (listener=0x7f9a3211ab20, > events=<value optimized out>) > at red_worker.c:10062 > #8 0x00007f9a77ab436d in red_worker_main (arg=<value optimized out>) at > red_worker.c:10304 > #9 0x0000003cec2077e1 in start_thread () from /lib64/libpthread.so.0 > #10 0x0000003cebae68ed in clone () from /lib64/libc.so.6 > > IMHO spice server should handle the display channel tear-down in the > dispatcher instead of the worker thread. Alon? > > >> Anyways, this commit fixes the problem at hand. > > Not really. channel_event() itself isn't thread-safe too, it does > unlocked list operations which can also blow up when called from > different threads. I thought my patch was at least a candidate for stable, but after this thread I'm convinced the problem should be fixed in spice instead. > > A patch like the attached (warning: untested) should do as quick&dirty > fix for stable. But IMO we really should fix spice instead. > > cheers, > Gerd >
