RE: [patch net-next v8 2/3] net: core: Add offload stats to if_stats_msg

[Nogah Frankel]

> -Original Message-
> From: Nikolay Aleksandrov [mailto:niko...@cumulusnetworks.com]
> Sent: Friday, September 09, 2016 4:39 PM
> To: Nikolay Aleksandrov <niko...@cumulusnetworks.com>
> Cc: Jiri Pirko <j...@resnulli.us>; Linux Kernel Network Developers 
> <netdev@vger.kernel.org>; David S. Miller
> <da...@davemloft.net>; Nogah Frankel <nog...@mellanox.com>; Ido Schimmel 
> <ido...@mellanox.com>; Elad Raz
> <el...@mellanox.com>; Yotam Gigi <yot...@mellanox.com>; Or Gerlitz 
> <ogerl...@mellanox.com>; ro...@cumulusnetworks.com;
> linvi...@tuxdriver.com; tg...@suug.ch; go...@cumulusnetworks.com; 
> sfel...@gmail.com; s...@queasysnail.net; Eran Ben Elisha
> <era...@mellanox.com>; a...@plumgrid.com; eduma...@google.com; 
> han...@stressinduktion.org; f.faine...@gmail.com;
> d...@cumulusnetworks.com
> Subject: Re: [patch net-next v8 2/3] net: core: Add offload stats to 
> if_stats_msg
> 
> 
> > On Sep 9, 2016, at 4:36 PM, Nikolay Aleksandrov 
> > <niko...@cumulusnetworks.com> wrote:
> >
> >>
> >> On Sep 8, 2016, at 9:19 AM, Jiri Pirko <j...@resnulli.us> wrote:
> >>
> >> From: Nogah Frankel <nog...@mellanox.com>
> >>
> >> Add a nested attribute of offload stats to if_stats_msg
> >> named IFLA_STATS_LINK_OFFLOAD_XSTATS.
> >> Under it, add SW stats, meaning stats only per packets that went via
> >> slowpath to the cpu, named IFLA_OFFLOAD_XSTATS_CPU_HIT.
> >>
> >> Signed-off-by: Nogah Frankel <nog...@mellanox.com>
> >> Signed-off-by: Jiri Pirko <j...@mellanox.com>
> >> ---
> >> include/uapi/linux/if_link.h |  9 
> >> net/core/rtnetlink.c | 97 
> >> ++--
> >> 2 files changed, 102 insertions(+), 4 deletions(-)
> >>
> > [snip]
> >> @@ -3655,6 +3725,22 @@ static int rtnl_fill_statsinfo(struct sk_buff *skb, 
> >> struct net_device *dev,
> >>}
> >>}
> >>
> >> +  if (stats_attr_valid(filter_mask, IFLA_STATS_LINK_OFFLOAD_XSTATS,
> >> +   *idxattr)) {
> >> +  attr = nla_nest_start(skb, IFLA_STATS_LINK_OFFLOAD_XSTATS);
> >> +  if (!attr)
> >> +  goto nla_put_failure;
> >> +
> >> +  err = rtnl_get_offload_stats(skb, dev);
> >> +  if (err == -ENODATA)
> >> +  nla_nest_cancel(skb, attr);
> >> +  else
> >> +  nla_nest_end(skb, attr);
> >> +
> >> +  if ((err) && (err != -ENODATA))
> >> +  goto nla_put_failure;
> >> +  }
> >> +
> >
> > Hmm, actually on a second read I think there’s a potential problem here. 
> > Since you don’t set *idxattr and if the space
> > isn’t enough the dump will get restarted and this will lead to an infinite 
> > loop.
> 
> Err, poor choice of words. I meant the loop will be for userspace since the 
> dump will err out at the same spot all the time so it
> won’t be able to ever finish. :-)
> 
> > I.e. if the previous attributes filled the skb and there’s not enough room 
> > for this one, it will return an error
> > but *idxattr will be == 0 from the previous attribute thus the whole dump 
> > will be restarted (this is in case someone
> > requests this attribute with some of the others of course).
> >
> > Cheers,
> > Nik
> >
> >

I'll fix it. Thanks.

> >>nlmsg_end(skb, nlh);
> >>
> >>return 0;
> >> @@ -3712,6 +3798,9 @@ static size_t if_nlmsg_stats_size(const struct 
> >> net_device *dev,
> >>}
> >>}
> >>
> >> +  if (stats_attr_valid(filter_mask, IFLA_STATS_LINK_OFFLOAD_XSTATS, 0))
> >> +  size += rtnl_get_offload_stats_size(dev);
> >> +
> >>return size;
> >> }
> >>
> >> --
> >> 2.5.5

Re: [patch net-next v8 2/3] net: core: Add offload stats to if_stats_msg

[Nikolay Aleksandrov]

> On Sep 8, 2016, at 9:19 AM, Jiri Pirko  wrote:
> 
> From: Nogah Frankel 
> 
> Add a nested attribute of offload stats to if_stats_msg
> named IFLA_STATS_LINK_OFFLOAD_XSTATS.
> Under it, add SW stats, meaning stats only per packets that went via
> slowpath to the cpu, named IFLA_OFFLOAD_XSTATS_CPU_HIT.
> 
> Signed-off-by: Nogah Frankel 
> Signed-off-by: Jiri Pirko 
> ---
> include/uapi/linux/if_link.h |  9 
> net/core/rtnetlink.c | 97 ++--
> 2 files changed, 102 insertions(+), 4 deletions(-)
> 
[snip]
> @@ -3655,6 +3725,22 @@ static int rtnl_fill_statsinfo(struct sk_buff *skb, 
> struct net_device *dev,
>   }
>   }
> 
> + if (stats_attr_valid(filter_mask, IFLA_STATS_LINK_OFFLOAD_XSTATS,
> +  *idxattr)) {
> + attr = nla_nest_start(skb, IFLA_STATS_LINK_OFFLOAD_XSTATS);
> + if (!attr)
> + goto nla_put_failure;
> +
> + err = rtnl_get_offload_stats(skb, dev);
> + if (err == -ENODATA)
> + nla_nest_cancel(skb, attr);
> + else
> + nla_nest_end(skb, attr);
> +
> + if ((err) && (err != -ENODATA))
> + goto nla_put_failure;
> + }
> +

Hmm, actually on a second read I think there’s a potential problem here. Since 
you don’t set *idxattr and if the space
isn’t enough the dump will get restarted and this will lead to an infinite loop.
I.e. if the previous attributes filled the skb and there’s not enough room for 
this one, it will return an error
but *idxattr will be == 0 from the previous attribute thus the whole dump will 
be restarted (this is in case someone
requests this attribute with some of the others of course).

Cheers,
 Nik


>   nlmsg_end(skb, nlh);
> 
>   return 0;
> @@ -3712,6 +3798,9 @@ static size_t if_nlmsg_stats_size(const struct 
> net_device *dev,
>   }
>   }
> 
> + if (stats_attr_valid(filter_mask, IFLA_STATS_LINK_OFFLOAD_XSTATS, 0))
> + size += rtnl_get_offload_stats_size(dev);
> +
>   return size;
> }
> 
> -- 
> 2.5.5
> 

Re: [patch net-next v8 2/3] net: core: Add offload stats to if_stats_msg

[Nikolay Aleksandrov]

> On Sep 9, 2016, at 4:36 PM, Nikolay Aleksandrov  
> wrote:
> 
>> 
>> On Sep 8, 2016, at 9:19 AM, Jiri Pirko  wrote:
>> 
>> From: Nogah Frankel 
>> 
>> Add a nested attribute of offload stats to if_stats_msg
>> named IFLA_STATS_LINK_OFFLOAD_XSTATS.
>> Under it, add SW stats, meaning stats only per packets that went via
>> slowpath to the cpu, named IFLA_OFFLOAD_XSTATS_CPU_HIT.
>> 
>> Signed-off-by: Nogah Frankel 
>> Signed-off-by: Jiri Pirko 
>> ---
>> include/uapi/linux/if_link.h |  9 
>> net/core/rtnetlink.c | 97 
>> ++--
>> 2 files changed, 102 insertions(+), 4 deletions(-)
>> 
> [snip]
>> @@ -3655,6 +3725,22 @@ static int rtnl_fill_statsinfo(struct sk_buff *skb, 
>> struct net_device *dev,
>>  }
>>  }
>> 
>> +if (stats_attr_valid(filter_mask, IFLA_STATS_LINK_OFFLOAD_XSTATS,
>> + *idxattr)) {
>> +attr = nla_nest_start(skb, IFLA_STATS_LINK_OFFLOAD_XSTATS);
>> +if (!attr)
>> +goto nla_put_failure;
>> +
>> +err = rtnl_get_offload_stats(skb, dev);
>> +if (err == -ENODATA)
>> +nla_nest_cancel(skb, attr);
>> +else
>> +nla_nest_end(skb, attr);
>> +
>> +if ((err) && (err != -ENODATA))
>> +goto nla_put_failure;
>> +}
>> +
> 
> Hmm, actually on a second read I think there’s a potential problem here. 
> Since you don’t set *idxattr and if the space
> isn’t enough the dump will get restarted and this will lead to an infinite 
> loop.

Err, poor choice of words. I meant the loop will be for userspace since the 
dump will err out at the same spot all the time so it
won’t be able to ever finish. :-)

> I.e. if the previous attributes filled the skb and there’s not enough room 
> for this one, it will return an error
> but *idxattr will be == 0 from the previous attribute thus the whole dump 
> will be restarted (this is in case someone
> requests this attribute with some of the others of course).
> 
> Cheers,
> Nik
> 
> 
>>  nlmsg_end(skb, nlh);
>> 
>>  return 0;
>> @@ -3712,6 +3798,9 @@ static size_t if_nlmsg_stats_size(const struct 
>> net_device *dev,
>>  }
>>  }
>> 
>> +if (stats_attr_valid(filter_mask, IFLA_STATS_LINK_OFFLOAD_XSTATS, 0))
>> +size += rtnl_get_offload_stats_size(dev);
>> +
>>  return size;
>> }
>> 
>> -- 
>> 2.5.5

Re: [patch net-next v8 2/3] net: core: Add offload stats to if_stats_msg

[Nikolay Aleksandrov]

> On Sep 8, 2016, at 9:19 AM, Jiri Pirko  wrote:
> 
> From: Nogah Frankel 
> 
> Add a nested attribute of offload stats to if_stats_msg
> named IFLA_STATS_LINK_OFFLOAD_XSTATS.
> Under it, add SW stats, meaning stats only per packets that went via
> slowpath to the cpu, named IFLA_OFFLOAD_XSTATS_CPU_HIT.
> 
> Signed-off-by: Nogah Frankel 
> Signed-off-by: Jiri Pirko 
> ---
> include/uapi/linux/if_link.h |  9 
> net/core/rtnetlink.c | 97 ++--
> 2 files changed, 102 insertions(+), 4 deletions(-)
> 
[snip]
> 
> + if (stats_attr_valid(filter_mask, IFLA_STATS_LINK_OFFLOAD_XSTATS,
> +  *idxattr)) {
> + attr = nla_nest_start(skb, IFLA_STATS_LINK_OFFLOAD_XSTATS);
> + if (!attr)
> + goto nla_put_failure;
> +
> + err = rtnl_get_offload_stats(skb, dev);
> + if (err == -ENODATA)
> + nla_nest_cancel(skb, attr);
> + else
> + nla_nest_end(skb, attr);
> +
> + if ((err) && (err != -ENODATA))
> + goto nla_put_failure;

Hi,
Sorry I’m a little late to the party, one minor nit though - could you please 
drop the extra braces here.
Overall the set looks good to me and you can add my

Reviewed-by: Nikolay Aleksandrov 

Thanks,
 Nik

> + }
> +
>   nlmsg_end(skb, nlh);
> 
>   return 0;
> @@ -3712,6 +3798,9 @@ static size_t if_nlmsg_stats_size(const struct 
> net_device *dev,
>   }
>   }
> 
> + if (stats_attr_valid(filter_mask, IFLA_STATS_LINK_OFFLOAD_XSTATS, 0))
> + size += rtnl_get_offload_stats_size(dev);
> +
>   return size;
> }
> 
> -- 
> 2.5.5
>