tc class的 parent 和classid参数疑问
// 以下是tc class的parent参数取值的说明parent == TC_H_UNSPEC - unspecified parent.
parent == TC_H_ROOT - class is root, which has no parent.
parent == X:0- parent is root class.
parent == X:Y- parent is a node in hierarchy.
parent == 0:Y- parent is X:Y, where X:0 is qdisc.
// 以下是tc class的classid参数取值的说明
handle == 0:0- generate handle from kernel pool.
handle == 0:Y- class is X:Y, where X:0 is qdisc.
handle == X:Y- clear.
handle == X:0- root class.
*/
static int tc_ctl_tclass(struct sk_buff *skb, struct nlmsghdr *n, void *arg)
{
struct tcmsg *tcm = NLMSG_DATA(n);
struct rtattr **tca = arg;
struct net_device *dev;
struct Qdisc *q = NULL;
struct Qdisc_class_ops *cops;
unsigned long cl = 0;
unsigned long new_cl;
u32 pid = tcm->tcm_parent;
u32 clid = tcm->tcm_handle;
u32 qid = TC_H_MAJ(clid);
int err;
if ((dev = __dev_get_by_index(tcm->tcm_ifindex)) == NULL)
return -ENODEV;
/*
parent == TC_H_UNSPEC - unspecified parent.
parent == TC_H_ROOT - class is root, which has no parent.
parent == X:0 - parent is root class.
parent == X:Y - parent is a node in hierarchy.
parent == 0:Y - parent is X:Y, where X:0 is qdisc.
handle == 0:0 - generate handle from kernel pool.
handle == 0:Y - class is X:Y, where X:0 is qdisc.
handle == X:Y - clear.
handle == X:0 - root class.
*/
/* Step 1. Determine qdisc handle X:0 */
if (pid != TC_H_ROOT) {
u32 qid1 = TC_H_MAJ(pid);
if (qid && qid1) {
/* If both majors are known, they must be identical. */
if (qid != qid1)
return -EINVAL;
} else if (qid1) {
qid = qid1;
} else if (qid == 0)
qid = dev->qdisc_sleeping->handle;
/* Now qid is genuine qdisc handle consistent
both with parent and child.
TC_H_MAJ(pid) still may be unspecified, complete it now.
*/
if (pid)
pid = TC_H_MAKE(qid, pid);
} else {
if (qid == 0)
qid = dev->qdisc_sleeping->handle;
}
弄不明白啊。有谁知道的吗
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