On 2017年01月16日 08:01, John Fastabend wrote:
Add support for XDP adjust head by allocating a 256B header region
that XDP programs can grow into. This is only enabled when a XDP
program is loaded.
In order to ensure that we do not have to unwind queue headroom push
queue setup below bpf_prog_add. It reads better to do a prog ref
unwind vs another queue setup call.
At the moment this code must do a full reset to ensure old buffers
without headroom on program add or with headroom on program removal
are not used incorrectly in the datapath. Ideally we would only
have to disable/enable the RX queues being updated but there is no
API to do this at the moment in virtio so use the big hammer. In
practice it is likely not that big of a problem as this will only
happen when XDP is enabled/disabled changing programs does not
require the reset. There is some risk that the driver may either
have an allocation failure or for some reason fail to correctly
negotiate with the underlying backend in this case the driver will
be left uninitialized. I have not seen this ever happen on my test
systems and for what its worth this same failure case can occur
from probe and other contexts in virtio framework.
Signed-off-by: John Fastabend <john.r.fastab...@intel.com>
---
drivers/net/virtio_net.c | 110 ++++++++++++++++++++++++++++++++++------------
1 file changed, 82 insertions(+), 28 deletions(-)
[...]
- vi->xdp_queue_pairs = xdp_qp;
netif_set_real_num_rx_queues(dev, curr_qp + xdp_qp);
for (i = 0; i < vi->max_queue_pairs; i++) {
@@ -1746,6 +1789,21 @@ static int virtnet_xdp_set(struct net_device *dev,
struct bpf_prog *prog)
}
return 0;
+
+virtio_reset_err:
+ /* On reset error do our best to unwind XDP changes inflight and return
+ * error up to user space for resolution. The underlying PCI reset hung
+ * on us so not much we can do here.
It should work with other transport, so let's remove "PCI" here.
+ */
+ dev_warn(&dev->dev, "XDP reset failure and queues unstable\n");
+ vi->xdp_queue_pairs = oxdp_qp;
+virtio_queue_err:
+ /* On queue set error we can unwind bpf ref count and user space can
+ * retry this is most likely an allocation failure.
+ */
+ if (prog)
+ bpf_prog_sub(prog, vi->max_queue_pairs - 1);
+ return err;
}
static bool virtnet_xdp_query(struct net_device *dev)
@@ -2373,7 +2431,6 @@ static void virtnet_remove(struct virtio_device *vdev)
free_netdev(vi->dev);
}
-#ifdef CONFIG_PM_SLEEP
static int virtnet_freeze(struct virtio_device *vdev)
{
struct virtnet_info *vi = vdev->priv;
@@ -2430,7 +2487,6 @@ static int virtnet_restore(struct virtio_device *vdev)
return 0;
}
-#endif
If you do want to use virtio_device_reset(), it's better to squash this
into patch 5/6.
Other looks good.
Thanks
