On Fri, 17 Jun 2011 21:39:26 +0530 Amit Shah <amit.s...@redhat.com> wrote:
> On (Fri) 17 Jun 2011 [10:16:44], Luiz Capitulino wrote: > > On Fri, 17 Jun 2011 12:17:36 +0530 > > Amit Shah <amit.s...@redhat.com> wrote: > > > > > On (Thu) 16 Jun 2011 [13:38:49], Luiz Capitulino wrote: > > > > If I start qemu with: > > > > > > > > # qemu -hda disks/test.img -enable-kvm -m 1G -snapshot \ > > > > -device virtio-serial \ > > > > -chardev socket,host=localhost,port=1234,server,nowait,id=foo \ > > > > -device virtserialport,chardev=foo,name=org.qemu.guest_agent > > > > > > > > I get a segfault when booting a Fedora 14 guest. The backtrace says: > > > > > > > > Program terminated with signal 11, Segmentation fault. > > > > #0 0x0000000000420850 in handle_control_message (vser=0x3732bd0, > > > > buf=0x2c173e0, len=8) at > > > > /home/lcapitulino/src/qmp-unstable/hw/virtio-serial-bus.c:335 > > > > 335 info = DO_UPCAST(VirtIOSerialPortInfo, qdev, port->dev.info); > > > > > > Strange, I've not seen it so far in my testing (neither in the daily > > > test runs of the virtio-serial testsuite). > > > > > > > I've also bisected this and git points out to commit: > > > > > > > > commit a15bb0d6a981de749452a5180fc8084d625671da > > > > Author: Markus Armbruster <arm...@redhat.com> > > > > Date: Wed May 25 14:21:13 2011 +0200 > > > > > > > > virtio-serial: Drop redundant VirtIOSerialPort member info > > > > > > > > I think what's happening is that the device is not initialized on a > > > > VIRTIO_CONSOLE_DEVICE_READY event. Moving the DO_UPCAST() call to > > > > the other events fixes the problem to me. > > > > > > > > Signed-off-by: Luiz Capitulino <lcapitul...@redhat.com> > > > > --- > > > > hw/virtio-serial-bus.c | 4 ++-- > > > > 1 files changed, 2 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c > > > > index 9a12104..579f676 100644 > > > > --- a/hw/virtio-serial-bus.c > > > > +++ b/hw/virtio-serial-bus.c > > > > @@ -332,8 +332,6 @@ static void handle_control_message(VirtIOSerial > > > > *vser, void *buf, size_t len) > > > > if (!port && cpkt.event != VIRTIO_CONSOLE_DEVICE_READY) > > > > return; > > > > > > > > - info = DO_UPCAST(VirtIOSerialPortInfo, qdev, port->dev.info); > > > > - > > > > > > Ah - this missed the !port check. It should be possible to do this in > > > a 'if (port)' block instead of replicating in the individual case > > > statements. > > > > > > Thanks for the debugging and patch; please update with the above and > > > I'll apply it to the virtio-serial tree. > > > > What about moving the VIRTIO_CONSOLE_DEVICE_READY handling out of the > > switch, like the patch below? This way the function is divided in a way > > that related events are handled together. > > > > I'll implement your first suggestion if you don't like this... > > > > diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c > > index 579f676..5f96245 100644 > > --- a/hw/virtio-serial-bus.c > > +++ b/hw/virtio-serial-bus.c > > @@ -325,19 +325,12 @@ static void handle_control_message(VirtIOSerial > > *vser, void *buf, size_t len) > > return; > > } > > > > - cpkt.event = lduw_p(&gcpkt->event); > > cpkt.value = lduw_p(&gcpkt->value); > > - > > - port = find_port_by_id(vser, ldl_p(&gcpkt->id)); > > - if (!port && cpkt.event != VIRTIO_CONSOLE_DEVICE_READY) > > - return; > > - > > - switch(cpkt.event) { > > - case VIRTIO_CONSOLE_DEVICE_READY: > > + cpkt.event = lduw_p(&gcpkt->event); > > + if (cpkt.event == VIRTIO_CONSOLE_DEVICE_READY) { > > if (!cpkt.value) { > > - error_report("virtio-serial-bus: Guest failure in adding > > device %s\n", > > - vser->bus.qbus.name); > > - break; > > + error_report("virtio-serial-bus: Guest failure in adding > > device %s\n", vser->bus.qbus.name); > > + return; > > The line split should remain -- else it goes beyond 80 chars. It's already beyond 80 chars to me. > > > } > > /* > > * The device is up, we can now tell the device about all the > > @@ -346,8 +339,13 @@ static void handle_control_message(VirtIOSerial *vser, > > void *buf, size_t len) > > QTAILQ_FOREACH(port, &vser->ports, next) { > > send_control_event(port, VIRTIO_CONSOLE_PORT_ADD, 1); > > } > > - break; > > + return; > > + } > > Makes me think of one case (totally unrelated to what you found)where > the guest can fool us: by sending multiple VIRTIO_CONSOLE_DEVICE_READY > messages. It will be handled just fine, no? > > > + port = find_port_by_id(vser, ldl_p(&gcpkt->id)); > > + assert(port != NULL); > > I doubt if assert is the right thing: if the guest sends bad data, we > shouldn't just kill it. It's easier to ignore such data, and perhaps > just log it. Right. > > > + > > + switch(cpkt.event) { > > case VIRTIO_CONSOLE_PORT_READY: > > if (!cpkt.value) { > > error_report("virtio-serial-bus: Guest failure in adding port > > %u for device %s\n", > > I'm fine with this approach. > > Amit >