[ovs-dev] [PATCH 2/2] netdev-linux: Simplify get_stats_via_netlink().
Alex Wang
alexw at nicira.com
Mon Dec 23 19:49:40 UTC 2013
Both patches look good to me,
One comment below,
> @@ -4432,57 +4432,38 @@ netdev_stats_from_rtnl_link_stats(struct
> netdev_stats *dst,
> static int
> get_stats_via_netlink(const struct netdev *netdev_, struct netdev_stats
> *stats)
> {
> - /* Policy for RTNLGRP_LINK messages.
> - *
> - * There are *many* more fields in these messages, but currently we
> only
> - * care about these fields. */
> - static const struct nl_policy rtnlgrp_link_policy[] = {
> - [IFLA_IFNAME] = { .type = NL_A_STRING, .optional = false },
> - [IFLA_STATS] = { .type = NL_A_UNSPEC, .optional = true,
> - .min_len = sizeof(struct rtnl_link_stats) },
> - };
> -
> struct ofpbuf request;
> struct ofpbuf *reply;
> - struct ifinfomsg *ifi;
> - struct nlattr *attrs[ARRAY_SIZE(rtnlgrp_link_policy)];
> - int ifindex;
> int error;
>
> - error = get_ifindex(netdev_, &ifindex);
> - if (error) {
> - return error;
> - }
> -
> ofpbuf_init(&request, 0);
> - nl_msg_put_nlmsghdr(&request, sizeof *ifi, RTM_GETLINK,
> NLM_F_REQUEST);
> - ifi = ofpbuf_put_zeros(&request, sizeof *ifi);
> - ifi->ifi_family = PF_UNSPEC;
> - ifi->ifi_index = ifindex;
> + nl_msg_put_nlmsghdr(&request,
> + sizeof(struct ifinfomsg) + NL_ATTR_SIZE(IFNAMSIZ),
> + RTM_GETLINK, NLM_F_REQUEST);
> + ofpbuf_put_zeros(&request, sizeof(struct ifinfomsg));
> + nl_msg_put_string(&request, IFLA_IFNAME, netdev_get_name(netdev_));
>
Why do we do "sizeof(struct ifinfomsg) + NL_ATTR_SIZE(IFNAMSIZ)"
instead of "sizeof(struct ifinfomsg)" or "sizeof(struct ifinfomsg) +
sizeof(struct nlattr) + NL_ATTR_SIZE(IFNAMSIZ) " ?
The "nl_msg_put_string(&request, IFLA_IFNAME, netdev_get_name(netdev_));"
will realloc the "reqest", since we also need to put "struct nlattr".
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