Thomas Weißschuh
2026-Jan-30 10:34 UTC
[klibc] [PATCH net-next v2 0/4] net: uapi: Provide an UAPI definition of 'struct sockaddr'
On Wed, Jan 21, 2026 at 07:27:29PM -0800, Jakub Kicinski wrote:> On Tue, 20 Jan 2026 15:10:30 +0100 Thomas Wei?schuh wrote: > > Various UAPI headers reference 'struct sockaddr'. Currently the > > definition of this struct is pulled in from the libc header > > sys/socket.h. This is problematic as it introduces a dependency > > on a full userspace toolchain. > > > > Add a definition of 'struct sockaddr' to the UAPI headers. > > Before that, reorder some problematic header inclusions in the selftests. > > > include/linux/socket.h | 10 ---------- > > include/uapi/linux/if.h | 4 ---- > > include/uapi/linux/libc-compat.h | 12 ++++++++++++ > > include/uapi/linux/socket.h | 14 ++++++++++++++ > > samples/bpf/xdp_adjust_tail_user.c | 6 ++++-- > > samples/bpf/xdp_fwd_user.c | 7 ++++--- > > samples/bpf/xdp_router_ipv4_user.c | 6 +++--- > > samples/bpf/xdp_sample_user.c | 15 ++++++++------- > > samples/bpf/xdp_tx_iptunnel_user.c | 4 ++-- > > tools/testing/selftests/landlock/audit.h | 7 ++++--- > > tools/testing/selftests/net/af_unix/diag_uid.c | 9 +++++---- > > tools/testing/selftests/net/busy_poller.c | 3 ++- > > tools/testing/selftests/net/mptcp/mptcp_diag.c | 11 ++++++----- > > tools/testing/selftests/net/nettest.c | 4 ++-- > > tools/testing/selftests/net/tcp_ao/icmps-discard.c | 6 +++--- > > tools/testing/selftests/net/tcp_ao/lib/netlink.c | 9 +++++---- > > tools/testing/selftests/net/tun.c | 5 +++-- > > 17 files changed, 77 insertions(+), 55 deletions(-) > > Are all those selftests / samples getting broken by this patch set?Yes. Some of them get broken by the new 'struct sockaddr', but some others are already broken just by the new transitive inclusion of libc-compat.h. So any header starting to use the compatibility machinery may trigger breakage in code including UAPI headers before libc header, even for completely new type definitions which themselves would not conflict with libc.> I understand that we should avoid libc dependencies in uAPI but at > least speaking for networking - building selftests without libc is.. > not a practical proposition?I am not sure I understand. Some sort of libc will always be necessary. And as the selftests are intended to exercise the low-level kernel APIs, even those not supported by libc, the UAPI headers will also be necessary. There is nolibc (tools/include/nolibc/) which is using the UAPI headers in most cases, and aims to be compatible. And can be and already is used for selftests, but it will be too limited for all of the networking selftests. (Disclaimer: I am maintaining nolibc) My goal is *not* to make the different headers less compatible on purpose. But by removing the existing dependencies we can now enforce the checks in CONFIG_UAPI_HEADER_TEST to prevent any new ones from creeping in. Therefore preventing compatiblity issues in any new UAPI. Thomas
Jakub Kicinski
2026-Jan-30 16:17 UTC
[klibc] [PATCH net-next v2 0/4] net: uapi: Provide an UAPI definition of 'struct sockaddr'
On Fri, 30 Jan 2026 11:34:15 +0100 Thomas Wei?schuh wrote:> > Are all those selftests / samples getting broken by this patch set? > > Yes. > > Some of them get broken by the new 'struct sockaddr', but some others are > already broken just by the new transitive inclusion of libc-compat.h. > So any header starting to use the compatibility machinery may trigger breakage > in code including UAPI headers before libc header, even for completely new type > definitions which themselves would not conflict with libc.Let's split the uAPI header changes from any selftest changes. If you're saying the the selftests no longer build after the uAPI header changes then of course we can't apply the patches.