On 4/27/16, 9:18 AM, Nikolay Aleksandrov wrote:
> We can't allow more than one stats attribute which uses the local idx
> since the result will be a mess. This is a simple check to make sure
> only one is being used at a time. Later when the filter_mask's 32 bits
> are over we can switch to a bitmap.
>
> Signed-off-by: Nikolay Aleksandrov <niko...@cumulusnetworks.com>
> ---
> include/net/rtnetlink.h | 6 ++++++
> net/core/rtnetlink.c | 17 +++++++++++++++--
> 2 files changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/include/net/rtnetlink.h b/include/net/rtnetlink.h
> index 2f87c1ba13de..3f3b0b1b8722 100644
> --- a/include/net/rtnetlink.h
> +++ b/include/net/rtnetlink.h
> @@ -150,4 +150,10 @@ int rtnl_nla_parse_ifla(struct nlattr **tb, const struct
> nlattr *head, int len);
>
> #define MODULE_ALIAS_RTNL_LINK(kind) MODULE_ALIAS("rtnl-link-" kind)
>
> +/* at most one attribute which can save a local idx is allowed to be set
> + * IFLA_STATS_IDX_ATTR_MASK has all the idx saving attributes set and is
> + * used to check if more than one is being requested
> + */
> +#define IFLA_STATS_IDX_ATTR_MASK 0
> +
> #endif
> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> index aeb2fa9b1cda..ea03b6cd3d3c 100644
> --- a/net/core/rtnetlink.c
> +++ b/net/core/rtnetlink.c
> @@ -3512,7 +3512,7 @@ static int rtnl_stats_get(struct sk_buff *skb, struct
> nlmsghdr *nlh)
> struct if_stats_msg *ifsm;
> struct net_device *dev = NULL;
> struct sk_buff *nskb;
> - u32 filter_mask;
> + u32 filter_mask, lidx_filter;
> int lidx = 0;
> int err;
>
> @@ -3529,6 +3529,14 @@ static int rtnl_stats_get(struct sk_buff *skb, struct
> nlmsghdr *nlh)
> if (!filter_mask)
> return -EINVAL;
>
> + /* only one attribute which can save a local idx is allowed at a time
> + * even though rtnl_stats_get doesn't save the lidx, we need to be
> + * consistent with the dump side and error out
> + */
> + lidx_filter = filter_mask & IFLA_STATS_IDX_ATTR_MASK;
> + if (lidx_filter && !is_power_of_2(lidx_filter))
> + return -EINVAL;
> +
> nskb = nlmsg_new(if_nlmsg_stats_size(dev, filter_mask), GFP_KERNEL);
> if (!nskb)
> return -ENOBUFS;
> @@ -3556,7 +3564,7 @@ static int rtnl_stats_dump(struct sk_buff *skb, struct
> netlink_callback *cb)
> struct net_device *dev;
> struct hlist_head *head;
> unsigned int flags = NLM_F_MULTI;
> - u32 filter_mask = 0;
> + u32 filter_mask = 0, lidx_filter;
> int err;
>
> s_h = cb->args[0];
> @@ -3570,6 +3578,11 @@ static int rtnl_stats_dump(struct sk_buff *skb, struct
> netlink_callback *cb)
> if (!filter_mask)
> return -EINVAL;
>
> + /* only one attribute which can save a local idx is allowed at a time */
> + lidx_filter = filter_mask & IFLA_STATS_IDX_ATTR_MASK;
> + if (lidx_filter && !is_power_of_2(lidx_filter))
> + return -EINVAL;
> +
>
instead of introducing the restriction at this level, is it possible to use two
args for this
like below and avoid the restriction ?
cb->args[2] = current filter being processed
cb->args[3] = private filter idx (your lidx)
