From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:43920) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T4fYM-0002Ul-Ei for qemu-devel@nongnu.org; Thu, 23 Aug 2012 18:07:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1T4fYL-0001xf-C4 for qemu-devel@nongnu.org; Thu, 23 Aug 2012 18:07:02 -0400 Received: from mail-ee0-f45.google.com ([74.125.83.45]:65302) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T4fYL-0001xV-4e for qemu-devel@nongnu.org; Thu, 23 Aug 2012 18:07:01 -0400 Received: by eeke53 with SMTP id e53so486940eek.4 for ; Thu, 23 Aug 2012 15:06:58 -0700 (PDT) Message-ID: <5036A97F.7030604@gmail.com> Date: Fri, 24 Aug 2012 02:06:55 +0400 From: Max Filippov MIME-Version: 1.0 References: <1345728155-11667-1-git-send-email-aliguori@us.ibm.com> In-Reply-To: <1345728155-11667-1-git-send-email-aliguori@us.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] monitor: move json init from OPEN event to init List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: qemu-devel@nongnu.org On Thu, Aug 23, 2012 at 5:22 PM, Anthony Liguori wrote: > At some point in the past, the OPEN event was changed to be issued from a > bottom half. This creates a small window whereas a data callback registered in > init may be invoked before the OPEN event has been issued. > > This is reproducible with: > > echo "{'execute': 'qmp_capabilities'}" | qemu-system-x86_64 -M none -qmp stdio > > We can fix this for the monitor by moving the parser initialization to init. > > The remaining state that is set in OPEN appears harmless. > > Reported-by: Daniel Berrange > Signed-off-by: Anthony Liguori > --- > monitor.c | 4 +++- > 1 files changed, 3 insertions(+), 1 deletions(-) > > diff --git a/monitor.c b/monitor.c > index 480f583..b188582 100644 > --- a/monitor.c > +++ b/monitor.c > @@ -4832,7 +4832,6 @@ static void monitor_control_event(void *opaque, int event) > switch (event) { > case CHR_EVENT_OPENED: > mon->mc->command_mode = 0; > - json_message_parser_init(&mon->mc->parser, handle_qmp_command); > data = get_qmp_greeting(); > monitor_json_emitter(mon, data); > qobject_decref(data); > @@ -4840,6 +4839,7 @@ static void monitor_control_event(void *opaque, int event) > break; > case CHR_EVENT_CLOSED: > json_message_parser_destroy(&mon->mc->parser); > + json_message_parser_init(&mon->mc->parser, handle_qmp_command); > mon_refcount--; > monitor_fdsets_cleanup(); > break; > @@ -4951,6 +4951,8 @@ void monitor_init(CharDriverState *chr, int flags) > monitor_event, mon); > } > > + json_message_parser_init(&mon->mc->parser, handle_qmp_command); > + This hunk causes SIGSEGV on qemu-system-xtensa with the following trace: Program received signal SIGSEGV, Segmentation fault. json_message_parser_init (parser=0x8, func=0x5555556b4db0 ) at qemu/json-streamer.c:98 98 parser->emit = func; (gdb) bt #0 json_message_parser_init (parser=0x8, func=0x5555556b4db0 ) at qemu/json-streamer.c:98 #1 0x00005555556ba5c7 in monitor_init (chr=0x555556228fe0, flags=2) at qemu/monitor.c:4954 #2 0x000055555564f83d in qemu_chr_new (label=, filename=, init=0) at qemu/qemu-char.c:2828 #3 0x0000555555626525 in serial_parse (devname=0x5555556f4152 "mon:stdio") at qemu/vl.c:2068 #4 serial_parse (devname=) at qemu/vl.c:2056 #5 0x0000555555625009 in foreach_device_config (type=2, func=0x5555556264b0 ) at qemu/vl.c:2048 #6 0x00005555555973f5 in main (argc=, argv=, envp=) at qemu/vl.c:3588 The command line is the following: qemu-system-xtensa -M sim -cpu dc232b -nographic -semihosting -kernel ./test_b.tst > QLIST_INSERT_HEAD(&mon_list, mon, entry); > if (!default_mon || (flags & MONITOR_IS_DEFAULT)) > default_mon = mon; > -- > 1.7.5.4 > > -- Thanks. -- Max