2021-07-19 05:19:57

by Yajun Deng

[permalink] [raw]
Subject: [PATCH] netlink: Deal with ESRCH error in nlmsg_notify()

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 <[email protected]>
Signed-off-by: Yajun Deng <[email protected]>
---
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;
}

--
2.32.0


2021-07-19 14:49:02

by Yonghong Song

[permalink] [raw]
Subject: Re: [PATCH] netlink: Deal with ESRCH error in nlmsg_notify()



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 <[email protected]>
> Signed-off-by: Yajun Deng <[email protected]>

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);

1 net/core/rtnetlink.c rtnl_notify 734 nlmsg_notify(rtnl, skb,
pid, group, report, flags);

2 net/netfilter/nfnetlink.c nfnetlink_send 176 return
nlmsg_notify(nfnlnet->nfnl, skb, portid, group, echo, flags);

3 net/netlink/genetlink.c genl_notify 1506 nlmsg_notify(sk, skb,
info->snd_portid, group, report, flags);

> ---
> 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;
> }
>
>

2021-07-20 02:58:24

by Yajun Deng

[permalink] [raw]
Subject: Re: [PATCH] netlink: Deal with ESRCH error in nlmsg_notify()

July 19, 2021 10:47 PM, "Yonghong Song" <[email protected]> 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 <[email protected]>
>> Signed-off-by: Yajun Deng <[email protected]>
>
> 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;
>> }
>>>

2021-07-20 04:31:42

by Cong Wang

[permalink] [raw]
Subject: Re: [PATCH] netlink: Deal with ESRCH error in nlmsg_notify()

On Sun, Jul 18, 2021 at 10:19 PM Yajun Deng <[email protected]> wrote:
> 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.

Looks like the tc-testing failure I saw is also due to this...

Why not just revert the above commit which does not have
much value? It at most saves some instructions.

Thanks.

2021-07-20 10:03:18

by patchwork-bot+netdevbpf

[permalink] [raw]
Subject: Re: [PATCH] netlink: Deal with ESRCH error in nlmsg_notify()

Hello:

This patch was applied to netdev/net-next.git (refs/heads/master):

On Mon, 19 Jul 2021 13:18:16 +0800 you 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)
>
> [...]

Here is the summary with links:
- netlink: Deal with ESRCH error in nlmsg_notify()
https://git.kernel.org/netdev/net-next/c/fef773fc8110

You are awesome, thank you!
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