> -----Original Message----- > From: Eric Dumazet [mailto:eric.dumazet@xxxxxxxxx] > Sent: Monday, March 19, 2012 1:12 PM > To: Haiyang Zhang > Cc: KY Srinivasan; davem@xxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx > Subject: Re: [PATCH 1/1] net/hyperv: Fix the code handling tx busy > > On Mon, 2012-03-19 at 10:02 -0700, Haiyang Zhang wrote: > > Instead of dropping the packet, we keep the skb buffer, and return > > NETDEV_TX_BUSY to let upper layer retry send. This will not cause > > endless loop, because the host is taking data away from ring buffer. > > > > Signed-off-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx> > > Reviewed-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx> > > --- > > drivers/net/hyperv/netvsc_drv.c | 5 +---- > > 1 files changed, 1 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/net/hyperv/netvsc_drv.c > > b/drivers/net/hyperv/netvsc_drv.c index 2517d20..dd29478 100644 > > --- a/drivers/net/hyperv/netvsc_drv.c > > +++ b/drivers/net/hyperv/netvsc_drv.c > > @@ -223,13 +223,10 @@ static int netvsc_start_xmit(struct sk_buff *skb, > struct net_device *net) > > net->stats.tx_bytes += skb->len; > > net->stats.tx_packets++; > > } else { > > - /* we are shutting down or bus overloaded, just drop packet > */ > > - net->stats.tx_dropped++; > > kfree(packet); > > - dev_kfree_skb_any(skb); > > } > > > > - return NETDEV_TX_OK; > > + return ret ? NETDEV_TX_BUSY : NETDEV_TX_OK; > > } > > > > /* > > Thats simply not true at all. > > A start_xmit() cannot do that. > > TX_BUSY should never be returned at all, its a deprecated code, for pretty > good reasons. (assuming queue is not stopped) We actually stop queue when the ring buffer is busy, see the code in netvsc.c > Try this on a machine with one CPU, I am pretty sure this can trigger > complete freezes. I have tested with one CPU. After NETDEV_TX_BUSY is returned, the Linux guest OS continues to respond without any problem. Thanks, - Haiyang _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
