LARTC��hello��
����I want to send a command "tc qdisc add dev eth0 root tbf rate 220kbit latency 50ms
burst 1540" from TC,
I found that a attribute with type of 1 is added to the nlmsg twice:
first time in the function of tc_qdisc_modify() in file of tc_qdisc.c:
"if (k[0])
addattr_l(&req.n, sizeof(req), TCA_KIND, k, strlen(k)+1);"
second time in the function of tbf_parse_opt() in file of q_tbf.c:
"addattr_l(n, 2024, TCA_TBF_PARMS, &opt, sizeof(opt));"
the value of TCA_KIND and TCA_TBF_PARAMS is 1,so the nlmsg consists two
attribute with type of 1.
when this nlmsg is dealed with in the kernel,I found a problem:
in the net/core/rtnetlink.c, function rtnetlink_rev_msg(),when:
"if (nlh->nlmsg_len > min_len) {
int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
struct rtattr *attr = (void*)nlh + NLMSG_ALIGN(min_len);
while (RTA_OK(attr, attrlen)) {
unsigned flavor = attr->rta_type;
if (flavor) {
if (flavor > rta_max[sz_idx])
goto err_inval;
rta[flavor-1] = attr;
}
attr = RTA_NEXT(attr, attrlen);
}
}"
at the begining of these lines, the first attribute(TCA_KIND) can be stored in
rta[1], but when handling
the second attribute, it is stored in the same rta[1]! so the first attribute
disappeared!!
of course the treatment followed will make a mistake.
who can tell me why?
������best regards!
����������������������������Mebius Huang
����������������������������[EMAIL PROTECTED]
����������������������������������2002-03-19
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