Re: [PATCH bpf-next v2 1/8] selftests/bpf: Add unshare_netns helper

On 5/15/24 6:13 PM, Geliang Tang wrote:

From: Geliang Tang tanggeliang@kylinos.cn

Many BPF selftests create new test network namespaces by using CLONE_NEWNET flag to unshare the network namespace, so that the calling process is moved into a new network namespace which is not shared with any previously existing process. So this patch adds a new helper in network_helpers.c named unshare_netns(), which create a new network namespace and set the net device lo up.

Signed-off-by: Geliang Tang tanggeliang@kylinos.cn

tools/testing/selftests/bpf/network_helpers.c | 19 +++++++++++++++++++ tools/testing/selftests/bpf/network_helpers.h | 1 + 2 files changed, 20 insertions(+)

diff --git a/tools/testing/selftests/bpf/network_helpers.c b/tools/testing/selftests/bpf/network_helpers.c index 35250e6cde7f..919bb2a0c6a6 100644 --- a/tools/testing/selftests/bpf/network_helpers.c +++ b/tools/testing/selftests/bpf/network_helpers.c @@ -670,3 +670,22 @@ int send_recv_data(int lfd, int fd, uint32_t total_bytes) return err; }

+int unshare_netns(void) +{

• int err;
• err = unshare(CLONE_NEWNET);
• if (err) {

• log_err("unshare netns failed");
  

• return err;
  

• }
• err = SYS_NOFAIL("ip link set dev lo up");

Losing useful error output is not good. Please find a way to keep them available such that it is easier to debug. The same goes for similar cases in this patch set. I think the only exception could be the "ip netns del" during cleanup.

Also, bpf CI reports a crash (should be the test #18 bpf_ip_check_defrag). Not sure how this set indirectly triggered it more easily:

https://github.com/kernel-patches/bpf/actions/runs/9290828674/job/2556900264...

pw-bot: cr

• if (err) {

• log_err("set dev lo up failed");
  

• return err;
  

• }
• return 0;

+} diff --git a/tools/testing/selftests/bpf/network_helpers.h b/tools/testing/selftests/bpf/network_helpers.h index 883c7ea9d8d5..b087330f2861 100644 --- a/tools/testing/selftests/bpf/network_helpers.h +++ b/tools/testing/selftests/bpf/network_helpers.h @@ -82,6 +82,7 @@ struct nstoken; struct nstoken *open_netns(const char *name); void close_netns(struct nstoken *token); int send_recv_data(int lfd, int fd, uint32_t total_bytes); +int unshare_netns(void); static __u16 csum_fold(__u32 csum) {