On Thu, Jun 10, 2010 at 10:17:07AM -0700, Sridhar Samudrala wrote: > On Thu, 2010-06-10 at 18:20 +0300, Michael S. Tsirkin wrote: > > virtio net will never try to overflow the TX ring, so the only reason > > add_buf may fail is out of memory. Thus, we can not stop the > > device until some request completes - there's no guarantee anything > > at all is outstanding. > > > > Make the error message clearer as well: error here does not > > indicate queue full. > > > > Signed-off-by: Michael S. Tsirkin <[email protected]> > > --- > > drivers/net/virtio_net.c | 15 ++++++++------- > > 1 files changed, 8 insertions(+), 7 deletions(-) > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > > index 85615a3..e48a06f 100644 > > --- a/drivers/net/virtio_net.c > > +++ b/drivers/net/virtio_net.c > > @@ -563,7 +563,6 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, > > struct net_device *dev) > > struct virtnet_info *vi = netdev_priv(dev); > > int capacity; > > > > -again: > > /* Free up any pending old buffers before queueing new ones. */ > > free_old_xmit_skbs(vi); > > > > @@ -572,12 +571,14 @@ again: > > > > /* This can happen with OOM and indirect buffers. */ > > if (unlikely(capacity < 0)) { > > - netif_stop_queue(dev); > > - dev_warn(&dev->dev, "Unexpected full queue\n"); > > - if (unlikely(!virtqueue_enable_cb(vi->svq))) { > > - virtqueue_disable_cb(vi->svq); > > - netif_start_queue(dev); > > - goto again; > > + if (net_ratelimit()) { > > + if (likely(capacity == -ENOMEM)) > > + dev_warn(&dev->dev, > > + "TX queue failure: out of memory\n"); > > + else > > + dev_warn(&dev->dev, > > + "Unexpected TX queue failure: %d\n", > > + capacity); > > } > > return NETDEV_TX_BUSY; > > } > > It is not clear to me how xmit_skb() can return -ENOMEM. > xmit_skb() calls virtqueue_add_buf_gfp() which can return -ENOSPC. > Even vring_add_indirect() doesn't return -ENOMEM on kmalloc failure. > > Thanks > Sridhar
A separate patch fixes vring_add_indirect to return -ENOMEM. -ENOSPC really means ring is full so nothing to do and no need to retry. -- MST _______________________________________________ Virtualization mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/virtualization
