bpf selftest tc_bpf failed with latest bpf-next

bpf selftest tc_bpf failed with latest bpf-next

[Yonghong Song]

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)
#132 tc_bpf:FAIL

The failure seems due to the commit
    cfdf0d9ae75b ("rtnetlink: use nlmsg_notify() in rtnetlink_send()")

Without the above commit, rtnetlink_send() will return 0 even if
netlink_broadcast() (called by rtnetlink_send())
returns an error. The above commit makes it return
an error code if netlink_broadcast() failed.

Such a rtnetlink_send() return value change impacted the return value
for tfilter_del_notify(), in sched/cls_api.c, in the above test.
Previously return 0, now return -3 (-ESRCH), causing the test failure.

I am not sure what is the proper solution to address this.
Should we just adjust test, or kernel change is also needed?

Kumar, Yajun, could you take a look?

Re: bpf selftest tc_bpf failed with latest bpf-next

[yajun.deng]

July 19, 2021 3:29 AM, "Yonghong Song" <yhs@fb.com> wrote:

> 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)
> #132 tc_bpf:FAIL
> 
> The failure seems due to the commit
> cfdf0d9ae75b ("rtnetlink: use nlmsg_notify() in rtnetlink_send()")
> 
> Without the above commit, rtnetlink_send() will return 0 even if
> netlink_broadcast() (called by rtnetlink_send())
> returns an error. The above commit makes it return
> an error code if netlink_broadcast() failed.
> 
> Such a rtnetlink_send() return value change impacted the return value
> for tfilter_del_notify(), in sched/cls_api.c, in the above test.
> Previously return 0, now return -3 (-ESRCH), causing the test failure.
> 
> I am not sure what is the proper solution to address this.
> Should we just adjust test, or kernel change is also needed?

Thanks report that, I'll route a patch to fix this in next submit.
> 
> Kumar, Yajun, could you take a look?