Re: [Xen-devel] Xen-unstable Linux 3.14-rc3 and 3.13 Network troubles "bisected"

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Mar 12, 2014 at 03:49:46PM +0100, Sander Eikelenboom wrote:
> 
> Wednesday, March 12, 2014, 3:48:26 PM, you wrote:
> 
> > On Wed, Mar 12, 2014 at 03:23:36PM +0100, Sander Eikelenboom wrote:
> > [...]
> >> > From the look of the code, 0 looks correct to me. Netback won't complain
> >> > about "bad gref" because it has no idea what a "good gref" looks like.
> >> > Only Xen has the knowledge whether a gref is legit. All netback sees is
> >> > the hypercall fails and it tries to push corresponding response to
> >> > netfront. But you can probably safely assume a gref larger than several
> >> > thousands be bad.
> >> 
> >> OK it's indeed netback setting the status to -1:
> >> 
> >> [  976.431585] vif vif-7-0 vif7.0: ?!? xenvif_rx_action status err? 
> >> status:-1 meta_slots_used:1 flags:3 size:958
> >> [ 1030.855057] vif vif-7-0 vif7.0: ?!? xenvif_rx_action status err? 
> >> status:-1 meta_slots_used:2 flags:7 size:2974
> >> [ 1030.861759] vif vif-7-0 vif7.0: ?!? xenvif_add_frag_responses status 
> >> err? status:-1 i:0 nr_meta_slots:1 flags:0 size:1460
> >> [ 1030.868499] vif vif-7-0 vif7.0: ?!? xenvif_rx_action status err? 
> >> status:-1 meta_slots_used:1 flags:3 size:958
> >> [ 1030.875278] vif vif-7-0 vif7.0: ?!? xenvif_rx_action status err? 
> >> status:-1 meta_slots_used:1 flags:3 size:2974
> >> [ 1068.199650] vif vif-7-0 vif7.0: ?!? xenvif_rx_action status err? 
> >> status:-1 meta_slots_used:8 flags:7 size:1634
> >> [ 1068.206479] vif vif-7-0 vif7.0: ?!? xenvif_add_frag_responses status 
> >> err? status:-1 i:0 nr_meta_slots:7 flags:4 size:2848
> >> [ 1068.213158] vif vif-7-0 vif7.0: ?!? xenvif_add_frag_responses status 
> >> err? status:-1 i:1 nr_meta_slots:7 flags:4 size:4096
> >> [ 1068.219701] vif vif-7-0 vif7.0: ?!? xenvif_add_frag_responses status 
> >> err? status:-1 i:2 nr_meta_slots:7 flags:4 size:4096
> >> [ 1068.226194] vif vif-7-0 vif7.0: ?!? xenvif_add_frag_responses status 
> >> err? status:-1 i:3 nr_meta_slots:7 flags:4 size:4096
> >> [ 1068.232728] vif vif-7-0 vif7.0: ?!? xenvif_add_frag_responses status 
> >> err? status:-1 i:4 nr_meta_slots:7 flags:4 size:4096
> >> [ 1068.239163] vif vif-7-0 vif7.0: ?!? xenvif_add_frag_responses status 
> >> err? status:-1 i:5 nr_meta_slots:7 flags:4 size:4096
> >> [ 1068.245397] vif vif-7-0 vif7.0: ?!? xenvif_add_frag_responses status 
> >> err? status:-1 i:6 nr_meta_slots:7 flags:0 size:1168
> >> [ 1068.251457] vif vif-7-0 vif7.0: ?!? xenvif_rx_action status err? 
> >> status:-1 meta_slots_used:1 flags:3 size:958
> >> 
> >> Now to find out why ..
> >> 
> 
> > -1 is the error code documented in netif.h, XEN_NETIF_RSP_ERROR.
> 
> grant copy fails ->> netback sets response status to -1.
> 
> > Assuming the traffic volumn is quite high both way (TX and RX), probably
> > worth checking if RX ring is overflowed. That is, if consumer pointer(s)
> > advance before producer pointer(s).
> 
> In what function ?
> 

That should be in RX path. Look for "RING_GET_REQUESTS(&vif->rx". That's
the macro to get a slot in RX ring; second argument is consumer index.
You can see if it advances before producer index.

Wei.

> > Wei.
> 

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel