On 03/28/2013 07:28 PM, Amit Shah wrote: > When multiple ovq operations are being performed (lots of open/close > operations on virtio_console fds), the __send_control_msg() function can > get confused without locking. > > A simple recipe to cause badness is: > * create a QEMU VM with two virtio-serial ports > * in the guest, do > while true;do echo abc >/dev/vport0p1;done > while true;do echo edf >/dev/vport0p2;done > > In one run, this caused a panic in __send_control_msg(). In another, I > got > > virtio_console virtio0: control-o:id 0 is not a head! > > This also results repeated messages similar to these on the host: > > qemu-kvm: virtio-serial-bus: Unexpected port id 478762112 for device > virtio-serial-bus.0 > qemu-kvm: virtio-serial-bus: Unexpected port id 478762368 for device > virtio-serial-bus.0 > > Reported-by: FuXiangChun <[email protected]> > Signed-off-by: Amit Shah <[email protected]> > --- > drivers/char/virtio_console.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c > index 7e9bc1d..410866c 100644 > --- a/drivers/char/virtio_console.c > +++ b/drivers/char/virtio_console.c > @@ -150,6 +150,7 @@ struct ports_device { > > /* To protect the vq operations for the control channel */ > spinlock_t c_ivq_lock; > + spinlock_t c_ovq_lock; > > /* The current config space is stored here */ > struct virtio_console_config config; > @@ -569,11 +570,14 @@ static ssize_t __send_control_msg(struct ports_device > *portdev, u32 port_id, > vq = portdev->c_ovq; > > sg_init_one(sg, &cpkt, sizeof(cpkt)); > + > + spin_lock_irq(&portdev->c_ovq_lock); > if (virtqueue_add_buf(vq, sg, 1, 0, &cpkt, GFP_ATOMIC) == 0) { > virtqueue_kick(vq); > while (!virtqueue_get_buf(vq, &len)) > cpu_relax(); > } > + spin_unlock_irq(&portdev->c_ovq_lock);
While you lock the irq, why don't we need to save and restore the irq flags here? Thanks, Wanlong Gao > return 0; > } > > @@ -1987,6 +1991,7 @@ static int virtcons_probe(struct virtio_device *vdev) > unsigned int nr_added_bufs; > > spin_lock_init(&portdev->c_ivq_lock); > + spin_lock_init(&portdev->c_ovq_lock); > INIT_WORK(&portdev->control_work, &control_work_handler); > > nr_added_bufs = fill_queue(portdev->c_ivq, > _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
