Messages in this thread | | | Date | Tue, 20 Jul 2021 02:47:01 +0000 | From | yajun.deng@linux ... | Subject | Re: [PATCH] netlink: Deal with ESRCH error in nlmsg_notify() |
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July 19, 2021 10:47 PM, "Yonghong Song" <yhs@fb.com> wrote:
> On 7/18/21 10:18 PM, Yajun Deng wrote: > >> Yonghong Song report: >> The bpf selftest tc_bpf failed with latest bpf-next. >> The following is the command to run and the result: >> $ ./test_progs -n 132 >> [ 40.947571] bpf_testmod: loading out-of-tree module taints kernel. >> test_tc_bpf:PASS:test_tc_bpf__open_and_load 0 nsec >> test_tc_bpf:PASS:bpf_tc_hook_create(BPF_TC_INGRESS) 0 nsec >> test_tc_bpf:PASS:bpf_tc_hook_create invalid hook.attach_point 0 nsec >> test_tc_bpf_basic:PASS:bpf_obj_get_info_by_fd 0 nsec >> test_tc_bpf_basic:PASS:bpf_tc_attach 0 nsec >> test_tc_bpf_basic:PASS:handle set 0 nsec >> test_tc_bpf_basic:PASS:priority set 0 nsec >> test_tc_bpf_basic:PASS:prog_id set 0 nsec >> test_tc_bpf_basic:PASS:bpf_tc_attach replace mode 0 nsec >> test_tc_bpf_basic:PASS:bpf_tc_query 0 nsec >> test_tc_bpf_basic:PASS:handle set 0 nsec >> test_tc_bpf_basic:PASS:priority set 0 nsec >> test_tc_bpf_basic:PASS:prog_id set 0 nsec >> libbpf: Kernel error message: Failed to send filter delete notification >> test_tc_bpf_basic:FAIL:bpf_tc_detach unexpected error: -3 (errno 3) >> test_tc_bpf:FAIL:test_tc_internal ingress unexpected error: -3 (errno 3) >> The failure seems due to the commit >> cfdf0d9ae75b ("rtnetlink: use nlmsg_notify() in rtnetlink_send()") >> Deal with ESRCH error in nlmsg_notify() even the report variable is zero. >> Reported-by: Yonghong Song <yhs@fb.com> >> Signed-off-by: Yajun Deng <yajun.deng@linux.dev> > > Thanks for quick fix. This does fix the bpf selftest issu. > But does this change have negative impacts on other > nlmsg_notify() callers, below 1-3 items? > > 0 net/core/rtnetlink.c rtnetlink_send 714 return nlmsg_notify(rtnl, skb, pid, group, echo, > GFP_KERNEL);
This is exactly what we need. > > 1 net/core/rtnetlink.c rtnl_notify 734 nlmsg_notify(rtnl, skb, pid, group, report, flags); > It doesn't matter because there is no return value.
> 2 net/netfilter/nfnetlink.c nfnetlink_send 176 return nlmsg_notify(nfnlnet->nfnl, skb, portid, > group, echo, flags); > It only ctnetlink_conntrack_event() use the return value when call nfnetlink_send() in net/netfilter/nf_conntrack_netlink.c, but it doesn't matter when the return value is ESRCH or zero.
> 3 net/netlink/genetlink.c genl_notify 1506 nlmsg_notify(sk, skb, info->snd_portid, group, report, > flags); > It doesn't matter because there is no return value.
I think the caller for nlmsg_notify() doesn't need deal with the ESRCH. It also deal with ESRCH when report variable is not zero.
>> --- >> net/netlink/af_netlink.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c >> index 380f95aacdec..24b7cf447bc5 100644 >> --- a/net/netlink/af_netlink.c >> +++ b/net/netlink/af_netlink.c >> @@ -2545,13 +2545,15 @@ int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 portid, >> /* errors reported via destination sk->sk_err, but propagate >> * delivery errors if NETLINK_BROADCAST_ERROR flag is set */ >> err = nlmsg_multicast(sk, skb, exclude_portid, group, flags); >> + if (err == -ESRCH) >> + err = 0; >> } >>> if (report) { >> int err2; >>> err2 = nlmsg_unicast(sk, skb, portid); >> - if (!err || err == -ESRCH) >> + if (!err) >> err = err2; >> } >>>
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