Sorry for the late review, just one hint here (no changes requested): On Mon, 9 Mar 2026 15:20:10 +0000 Aleksei Oladko <[email protected]> wrote:
> The reuseport_* tests (bpf, bpf_cpu, bpf_numa, dualstack) currently use > a fixed port range. This can cause intermittent test failures when the > ports are already in use by other services: > > failed to bind receive socket: Address already in use > > To avoid conflicts, run these tests in separate network namespaces using > unshare. Each test now has its own isolated network stack, preventing > port collisions with the host services. > > Signed-off-by: Aleksei Oladko <[email protected]> > --- > tools/testing/selftests/net/reuseport_bpf.c | 11 +++++++++++ > tools/testing/selftests/net/reuseport_bpf_cpu.c | 10 ++++++++++ > tools/testing/selftests/net/reuseport_bpf_numa.c | 10 ++++++++++ > tools/testing/selftests/net/reuseport_dualstack.c | 11 +++++++++++ > 4 files changed, 42 insertions(+) > > diff --git a/tools/testing/selftests/net/reuseport_bpf.c > b/tools/testing/selftests/net/reuseport_bpf.c > index b6634d6da3d6..12e48b97b862 100644 > --- a/tools/testing/selftests/net/reuseport_bpf.c > +++ b/tools/testing/selftests/net/reuseport_bpf.c > @@ -23,6 +23,7 @@ > #include <sys/socket.h> > #include <sys/resource.h> > #include <unistd.h> > +#include <sched.h> > > #include "kselftest.h" > > @@ -455,8 +456,18 @@ static __attribute__((destructor)) void main_dtor(void) > setrlimit(RLIMIT_MEMLOCK, &rlim_old); > } > > +static void setup_netns(void) > +{ > + if (unshare(CLONE_NEWNET)) > + error(1, errno, "failed to unshare netns"); > + if (system("ip link set lo up")) > + error(1, 0, "failed to bring up lo interface in netns"); I don't have much against this approach, except that it needs root / UID 0 (but these are BPF tests anyway, and that was also the case for 3/5 before), and that it's a bit ugly to invoke ip-link like that. Anyway, should you or somebody else ever need a snippet that does this as unprivileged user (giving CLONE_NEWUSER at the same time) and without external tools or libraries, I made this a while ago: https://archives.passt.top/passt-dev/20231206160808.3d312733@elisabeth/ It detaches the network namespace, brings up 'lo' with a minimalistic netlink implementation, and lets you do whatever you need there. I guess ideally it could live under selftests/net/lib/ and be used from C programs or as stand-alone tool for shell scripts as well. I don't see myself polishing things up and proposing that in the foreseeable future, but I thought maybe you're interested in it. > +} > + > int main(void) > { > + setup_netns(); > + > fprintf(stderr, "---- IPv4 UDP ----\n"); > /* NOTE: UDP socket lookups traverse a different code path when there > * are > 10 sockets in a group. Run the bpf test through both paths. > diff --git a/tools/testing/selftests/net/reuseport_bpf_cpu.c > b/tools/testing/selftests/net/reuseport_bpf_cpu.c > index 2d646174729f..ddfe92f6597a 100644 > --- a/tools/testing/selftests/net/reuseport_bpf_cpu.c > +++ b/tools/testing/selftests/net/reuseport_bpf_cpu.c > @@ -228,10 +228,20 @@ static void test(int *rcv_fd, int len, int family, int > proto) > close(rcv_fd[cpu]); > } > > +static void setup_netns(void) > +{ > + if (unshare(CLONE_NEWNET)) > + error(1, errno, "failed to unshare netns"); > + if (system("ip link set lo up")) > + error(1, 0, "failed to bring up lo interface in netns"); > +} > + > int main(void) > { > int *rcv_fd, cpus; > > + setup_netns(); > + > cpus = sysconf(_SC_NPROCESSORS_ONLN); > if (cpus <= 0) > error(1, errno, "failed counting cpus"); > diff --git a/tools/testing/selftests/net/reuseport_bpf_numa.c > b/tools/testing/selftests/net/reuseport_bpf_numa.c > index 2ffd957ffb15..8ec52fc5ef41 100644 > --- a/tools/testing/selftests/net/reuseport_bpf_numa.c > +++ b/tools/testing/selftests/net/reuseport_bpf_numa.c > @@ -230,10 +230,20 @@ static void test(int *rcv_fd, int len, int family, int > proto) > close(rcv_fd[node]); > } > > +static void setup_netns(void) > +{ > + if (unshare(CLONE_NEWNET)) > + error(1, errno, "failed to unshare netns"); > + if (system("ip link set lo up")) > + error(1, 0, "failed to bring up lo interface in netns"); > +} > + > int main(void) > { > int *rcv_fd, nodes; > > + setup_netns(); > + > if (numa_available() < 0) > ksft_exit_skip("no numa api support\n"); > > diff --git a/tools/testing/selftests/net/reuseport_dualstack.c > b/tools/testing/selftests/net/reuseport_dualstack.c > index fb7a59ed759e..0eaf739d0c85 100644 > --- a/tools/testing/selftests/net/reuseport_dualstack.c > +++ b/tools/testing/selftests/net/reuseport_dualstack.c > @@ -25,6 +25,7 @@ > #include <sys/types.h> > #include <sys/socket.h> > #include <unistd.h> > +#include <sched.h> > > static const int PORT = 8888; > > @@ -156,10 +157,20 @@ static void test(int *rcv_fds, int count, int proto) > close(epfd); > } > > +static void setup_netns(void) > +{ > + if (unshare(CLONE_NEWNET)) > + error(1, errno, "failed to unshare netns"); > + if (system("ip link set lo up")) > + error(1, 0, "failed to bring up lo interface in netns"); > +} > + > int main(void) > { > int rcv_fds[32], i; > > + setup_netns(); > + > fprintf(stderr, "---- UDP IPv4 created before IPv6 ----\n"); > build_rcv_fd(AF_INET, SOCK_DGRAM, rcv_fds, 5); > build_rcv_fd(AF_INET6, SOCK_DGRAM, &(rcv_fds[5]), 5); -- Stefano
