Re: [PATCH] IPROUTE: correct nla nested message generated by netem_parse_opt

[Stephen Hemminger <shemminger@vyatta.com>]

On Thu, 21 Aug 2008 17:50:11 -0700
Jeff Kirsher <jeffrey.t.kirsher@intel.com> wrote:

> From: Alexander Duyck <alexander.h.duyck@intel.com>
> 
> netem_parse_opt was generating a malformed nested compat message.  This patch
> corrects it so that the nested arguments are contained within a nested nla
> header.
> 
> Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
> ---
> 
>  tc/q_netem.c |    9 +++------
>  1 files changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/tc/q_netem.c b/tc/q_netem.c
> index d06932e..a3365c1 100644
> --- a/tc/q_netem.c
> +++ b/tc/q_netem.c
> @@ -128,7 +128,7 @@ static int netem_parse_opt(struct qdisc_util *qu, int argc, char **argv,
>  			   struct nlmsghdr *n)
>  {
>  	size_t dist_size = 0;
> -	struct rtattr *tail;
> +	struct rtattr *nest;
>  	struct tc_netem_qopt opt;
>  	struct tc_netem_corr cor;
>  	struct tc_netem_reorder reorder;
> @@ -257,8 +257,6 @@ static int netem_parse_opt(struct qdisc_util *qu, int argc, char **argv,
>  		argc--; argv++;
>  	}
>  
> -	tail = NLMSG_TAIL(n);
> -
>  	if (reorder.probability) {
>  		if (opt.latency == 0) {
>  			fprintf(stderr, "reordering not possible without specifying some delay\n");
> @@ -277,8 +275,7 @@ static int netem_parse_opt(struct qdisc_util *qu, int argc, char **argv,
>  		return -1;
>  	}
>  
> -	if (addattr_l(n, 1024, TCA_OPTIONS, &opt, sizeof(opt)) < 0)
> -		return -1;
> +	nest = addattr_nest_compat(n, 1024, TCA_OPTIONS, &opt, sizeof(opt));
>  
>  	if (present[TCA_NETEM_CORR] &&
>  	    addattr_l(n, 1024, TCA_NETEM_CORR, &cor, sizeof(cor)) < 0)
> @@ -299,7 +296,7 @@ static int netem_parse_opt(struct qdisc_util *qu, int argc, char **argv,
>  			return -1;
>  		free(dist_data);
>  	}
> -	tail->rta_len = (void *) NLMSG_TAIL(n) - (void *) tail;
> +	addattr_nest_compat_end(n, nest);
>  	return 0;
>  }
>  
> 

The kernel ABI can not change? The nested attribute order should not change.