[PATCH] Check device status in tx timer

[PATCH] Check device status in tx timer

[Dor Laor]

repository: /home/dor/src/merge/kvm
branch: trunk
commit acdb6d2aa7332179eead306ead17494ae23edbd6
Author: Dor Laor <dor.laor@qumranet.com>
Date:   Tue Mar 4 08:16:06 2008 -0500

    Check device status in tx timer.
    
    The device can be down when the timer pops.
    If it is down it will cause segfault.
    It might happen on migration but also on regular operation
    when the device sends packets and quickly goes down before
    the host timer pops.
    
    Signed-off-by: Dor Laor <dor.laor@qumranet.com>

diff --git a/qemu/hw/virtio-net.c b/qemu/hw/virtio-net.c
index 612cf6b..a05eafb 100644
--- a/qemu/hw/virtio-net.c
+++ b/qemu/hw/virtio-net.c
@@ -280,6 +280,10 @@ static void virtio_net_tx_timer(void *opaque)
 {
     VirtIONet *n = opaque;
 
+    /* Just in case the driver is not ready on more */
+    if (!(n->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK))
+        return;
+
     n->tx_vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY;
     n->tx_timer_active = 0;
     virtio_net_flush_tx(n, n->tx_vq);


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Re: [PATCH] Check device status in tx timer

[Dor Laor]

On Tue, 2008-03-04 at 09:42 -0600, Anthony Liguori wrote:
> > diff --git a/qemu/hw/virtio-net.c b/qemu/hw/virtio-net.c
> > index 612cf6b..a05eafb 100644
> > --- a/qemu/hw/virtio-net.c
> > +++ b/qemu/hw/virtio-net.c
> > @@ -280,6 +280,10 @@ static void virtio_net_tx_timer(void *opaque)
> >  {
> >      VirtIONet *n = opaque;
> >
> > +    /* Just in case the driver is not ready on more */
> > +    if (!(n->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK))
> > +        return;
> > +
> >   
> 
> You probably want to set tx_timer_active = 0 here too.
> 

yap, thanks.

> Regards,
> 
> Anthony Liguori
> 
> >      n->tx_vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY;
> >      n->tx_timer_active = 0;
> >      virtio_net_flush_tx(n, n->tx_vq);
> >
> >   
> 


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