On 19 Dec 2022, at 13:20, Ilya Maximets wrote:

> AF_XDP functions was deprecated in libbpf 0.7 and moved to libxdp.
> Functions bpf_get/set_link_xdp_id() was deprecated in libbpf 0.8
> and replaced with bpf_xdp_query_id() and bpf_xdp_attach/detach().
>
> Updating configuration and source code to accommodate above changes
> and allow building OVS with AF_XDP support on newer systems:
>
>  - Checking availability of the libxdp in a system by looking
>    for a library providing libxdp_strerror().
>
>  - Checking for xsk.h header provided by libxdp-dev[el] first,
>    fall back to xsk.h from libbpf if not found.
>
>  - Check for the NEED_WAKEUP feature replaced with direct checking
>    in the source code if XDP_USE_NEED_WAKEUP is defined.
>
>  - Checking availability of bpf_xdp_query_id and bpf_xdp_detach
>    and using them instead of deprecated APIs.  Fall back to old
>    functions if not found.

So I guess this requires our build environment to match our runtime 
environment, as these functions are from dynamic libraries, not statically 
linked?

I guess this is find, as long as people understand it.

>
>  - Dropped LIBBPF_LDADD variable as it makes library and function
>    detection much harder without providing any actual benefits.
>    AC_SEARCH_LIBS is used instead and it allows use of AC_CHECK_FUNCS.
>
>  - Header includes moved around to files where they are actually used.
>
>  - Removed libelf dependency as it is not really used.
>
> With these changes it should be possible to build OVS with either:
>
>  - libbpf built from the kernel sources (5.19 or older).
>  - libbpf < 0.7 provided in distributions.
>  - libxdp and libbpf >= 0.7 provided in newer distributions.
>
> libxdp added as a build dependency for Fedora build since all
> supported versions of Fedora are packaging this library.
>
> Signed-off-by: Ilya Maximets <[email protected]>

I have problems building this on my fedora35 system with 
gcc-11.3.1-3.fc35.x86_64:

libtool: link: ( cd "include/openvswitch/.libs" && rm -f "libcxxtest.la" && ln 
-s "../libcxxtest.la" "libcxxtest.la" )
In file included from lib/netdev-linux-private.h:30,
                 from lib/netdev-afxdp.c:19:
In function ‘dp_packet_delete’,
    inlined from ‘dp_packet_delete’ at lib/dp-packet.h:246:1,
    inlined from ‘dp_packet_batch_add__’ at lib/dp-packet.h:775:9,
    inlined from ‘dp_packet_batch_add’ at lib/dp-packet.h:783:5,
    inlined from ‘netdev_afxdp_rxq_recv’ at lib/netdev-afxdp.c:894:9:
lib/dp-packet.h:260:9: error: ‘free’ called on pointer ‘*umem.xpool.array’ with 
nonzero offset [8, 2558044588346441168] [-Werror=free-nonheap-object]
  260 |         free(b);
      |         ^~~~~~~

Guess it does not recognise the (b->source == DPBUF_AFXDP) statement…

This is my build config:

./configure --enable-Werror --enable-usdt-probes --localstatedir=/var 
--prefix=/usr --sysconfdir=/etc --enable-afxdp

Guess this should be fixed before we enable afxdp by default?


Also when I build it without the Werror option I’m not able to start a sandbox:

make[1]: Leaving directory '/home/echaudron/Documents/review/ovs_ilya_afxdp'
ovsdb-tool create conf.db 
/home/echaudron/Documents/review/ovs_ilya_afxdp/vswitchd/vswitch.ovsschema
ovsdb-tool: symbol lookup error: /lib64/libxdp.so.1: undefined symbol: 
silence_libbpf_logging
cat: '/home/echaudron/Documents/review/ovs_ilya_afxdp/tutorial/sandbox/*.pid': 
No such file or directory

But this might be something specific to libxdp on my system, and libbpf :(

> ---
>  NEWS                            |  2 ++
>  acinclude.m4                    | 21 +++++++++---------
>  lib/automake.mk                 |  1 -
>  lib/libopenvswitch.pc.in        |  2 +-
>  lib/netdev-afxdp-pool.c         |  2 ++
>  lib/netdev-afxdp-pool.h         |  5 -----
>  lib/netdev-afxdp.c              | 38 ++++++++++++++++++++++++++-------
>  rhel/openvswitch-fedora.spec.in |  2 +-
>  8 files changed, 46 insertions(+), 27 deletions(-)
>
> diff --git a/NEWS b/NEWS
> index 265375e1c..5d39c7d27 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -1,5 +1,7 @@
>  Post-v3.0.0
>  --------------------
> +   - AF_XDP:
> +     * Added support for building with libxdp and libbpf >= 0.7.
>     - ovs-appctl:
>       * "ovs-appctl ofproto/trace" command can now display port names with the
>         "--names" option.
> diff --git a/acinclude.m4 b/acinclude.m4
> index aa9af5506..aed01c967 100644
> --- a/acinclude.m4
> +++ b/acinclude.m4
> @@ -251,7 +251,7 @@ AC_DEFUN([OVS_FIND_DEPENDENCY], [
>
>  dnl OVS_CHECK_LINUX_AF_XDP
>  dnl
> -dnl Check both Linux kernel AF_XDP and libbpf support
> +dnl Check both Linux kernel AF_XDP and libbpf/libxdp support
>  AC_DEFUN([OVS_CHECK_LINUX_AF_XDP], [
>    AC_ARG_ENABLE([afxdp],
>                  [AS_HELP_STRING([--enable-afxdp], [Enable AF-XDP support])],
> @@ -270,23 +270,22 @@ AC_DEFUN([OVS_CHECK_LINUX_AF_XDP], [
>      AC_CHECK_HEADER([linux/if_xdp.h], [],
>        [AC_MSG_ERROR([unable to find linux/if_xdp.h for AF_XDP support])])
>
> -    AC_CHECK_HEADER([bpf/xsk.h], [],
> -      [AC_MSG_ERROR([unable to find bpf/xsk.h for AF_XDP support])])
> +    AC_CHECK_HEADER([xdp/xsk.h],
> +      AC_DEFINE([HAVE_LIBXDP], [1], [xsk.h is supplied with libxdp]),
> +      AC_CHECK_HEADER([bpf/xsk.h], [],
> +        [AC_MSG_ERROR([unable to find xsk.h for AF_XDP support])]))
>
>      AC_CHECK_FUNCS([pthread_spin_lock], [],
>        [AC_MSG_ERROR([unable to find pthread_spin_lock for AF_XDP support])])
>
>      OVS_FIND_DEPENDENCY([numa_alloc_onnode], [numa], [libnuma])
> +    OVS_FIND_DEPENDENCY([libbpf_strerror], [bpf], [libbpf])
> +    AC_SEARCH_LIBS([libxdp_strerror], [xdp])
> +
> +    AC_CHECK_FUNCS([bpf_xdp_query_id bpf_xdp_detach])
>
>      AC_DEFINE([HAVE_AF_XDP], [1],
>                [Define to 1 if AF_XDP support is available and enabled.])
> -    LIBBPF_LDADD=" -lbpf -lelf"
> -    AC_SUBST([LIBBPF_LDADD])
> -
> -    AC_CHECK_DECL([xsk_ring_prod__needs_wakeup], [
> -      AC_DEFINE([HAVE_XDP_NEED_WAKEUP], [1],
> -        [XDP need wakeup support detected in xsk.h.])
> -    ], [], [[#include <bpf/xsk.h>]])
>    fi
>    AM_CONDITIONAL([HAVE_AF_XDP], test "$AF_XDP_ENABLE" = true)
>  ])
> @@ -357,7 +356,7 @@ AC_DEFUN([OVS_CHECK_DPDK], [
>      ], [], [[#include <rte_config.h>]])
>
>      AC_CHECK_DECL([RTE_NET_AF_XDP], [
> -      LIBBPF_LDADD="-lbpf"
> +      OVS_FIND_DEPENDENCY([libbpf_strerror], [bpf], [libbpf])
>      ], [], [[#include <rte_config.h>]])
>
>      AC_CHECK_DECL([RTE_LIBRTE_VHOST_NUMA], [
> diff --git a/lib/automake.mk b/lib/automake.mk
> index a0fabe38f..61bdc308f 100644
> --- a/lib/automake.mk
> +++ b/lib/automake.mk
> @@ -9,7 +9,6 @@ lib_LTLIBRARIES += lib/libopenvswitch.la
>
>  lib_libopenvswitch_la_LIBADD = $(SSL_LIBS)
>  lib_libopenvswitch_la_LIBADD += $(CAPNG_LDADD)
> -lib_libopenvswitch_la_LIBADD += $(LIBBPF_LDADD)
>
>
>  if WIN32
> diff --git a/lib/libopenvswitch.pc.in b/lib/libopenvswitch.pc.in
> index 44fbb1f9f..a5f4d3947 100644
> --- a/lib/libopenvswitch.pc.in
> +++ b/lib/libopenvswitch.pc.in
> @@ -7,5 +7,5 @@ Name: libopenvswitch
>  Description: Open vSwitch library
>  Version: @VERSION@
>  Libs: -L${libdir} -lopenvswitch
> -Libs.private: @LIBS@ @SSL_LIBS@ @CAPNG_LDADD@ @LIBBPF_LDADD@
> +Libs.private: @LIBS@ @SSL_LIBS@ @CAPNG_LDADD@
>  Cflags: -I${includedir}
> diff --git a/lib/netdev-afxdp-pool.c b/lib/netdev-afxdp-pool.c
> index 3386d2dcf..f56a7b29e 100644
> --- a/lib/netdev-afxdp-pool.c
> +++ b/lib/netdev-afxdp-pool.c
> @@ -15,6 +15,8 @@
>   */
>  #include <config.h>
>

Remove new line here?

> +#include <errno.h>
> +
>  #include "dp-packet.h"
>  #include "netdev-afxdp-pool.h"
>  #include "openvswitch/util.h"
> diff --git a/lib/netdev-afxdp-pool.h b/lib/netdev-afxdp-pool.h
> index f929b9489..6681cf539 100644
> --- a/lib/netdev-afxdp-pool.h
> +++ b/lib/netdev-afxdp-pool.h
> @@ -19,12 +19,7 @@
>
>  #ifdef HAVE_AF_XDP
>
> -#include <bpf/xsk.h>
> -#include <errno.h>
> -#include <stdbool.h>
> -
>  #include "openvswitch/thread.h"
> -#include "ovs-atomic.h"
>
>  /* LIFO ptr_array. */
>  struct umem_pool {
> diff --git a/lib/netdev-afxdp.c b/lib/netdev-afxdp.c
> index ca3f2431e..6ced8a2b6 100644
> --- a/lib/netdev-afxdp.c
> +++ b/lib/netdev-afxdp.c
> @@ -21,6 +21,11 @@
>  #include "netdev-afxdp.h"
>  #include "netdev-afxdp-pool.h"
>
> +#ifdef HAVE_LIBXDP
> +#include <xdp/xsk.h>
> +#else
> +#include <bpf/xsk.h>
> +#endif
>  #include <errno.h>
>  #include <inttypes.h>
>  #include <linux/rtnetlink.h>
> @@ -29,6 +34,7 @@
>  #include <numa.h>
>  #include <numaif.h>
>  #include <poll.h>
> +#include <stdbool.h>
>  #include <stdlib.h>
>  #include <sys/resource.h>
>  #include <sys/socket.h>
> @@ -44,6 +50,7 @@
>  #include "openvswitch/list.h"
>  #include "openvswitch/thread.h"
>  #include "openvswitch/vlog.h"
> +#include "ovs-atomic.h"
>  #include "ovs-numa.h"
>  #include "packets.h"
>  #include "socket-util.h"
> @@ -72,7 +79,7 @@ static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 
> 20);
>  #define PROD_NUM_DESCS      XSK_RING_PROD__DEFAULT_NUM_DESCS
>  #define CONS_NUM_DESCS      XSK_RING_CONS__DEFAULT_NUM_DESCS
>
> -#ifdef HAVE_XDP_NEED_WAKEUP
> +#ifdef XDP_USE_NEED_WAKEUP
>  #define NEED_WAKEUP_DEFAULT true
>  #else
>  #define NEED_WAKEUP_DEFAULT false
> @@ -169,7 +176,7 @@ struct netdev_afxdp_tx_lock {
>      );
>  };
>
> -#ifdef HAVE_XDP_NEED_WAKEUP
> +#ifdef XDP_USE_NEED_WAKEUP
>  static inline void
>  xsk_rx_wakeup_if_needed(struct xsk_umem_info *umem,
>                          struct netdev *netdev, int fd)
> @@ -201,7 +208,7 @@ xsk_tx_need_wakeup(struct xsk_socket_info *xsk_info)
>      return xsk_ring_prod__needs_wakeup(&xsk_info->tx);
>  }
>
> -#else /* !HAVE_XDP_NEED_WAKEUP */
> +#else /* !XDP_USE_NEED_WAKEUP */
>  static inline void
>  xsk_rx_wakeup_if_needed(struct xsk_umem_info *umem OVS_UNUSED,
>                          struct netdev *netdev OVS_UNUSED,
> @@ -215,7 +222,7 @@ xsk_tx_need_wakeup(struct xsk_socket_info *xsk_info 
> OVS_UNUSED)
>  {
>      return true;
>  }
> -#endif /* HAVE_XDP_NEED_WAKEUP */
> +#endif /* XDP_USE_NEED_WAKEUP */
>
>  static void
>  netdev_afxdp_cleanup_unused_pool(struct unused_pool *pool)
> @@ -351,7 +358,7 @@ xsk_configure_socket(struct xsk_umem_info *umem, uint32_t 
> ifindex,
>      cfg.bind_flags = xdp_modes[mode].bind_flags;
>      cfg.xdp_flags = xdp_modes[mode].xdp_flags | XDP_FLAGS_UPDATE_IF_NOEXIST;
>
> -#ifdef HAVE_XDP_NEED_WAKEUP
> +#ifdef XDP_USE_NEED_WAKEUP
>      if (use_need_wakeup) {
>          cfg.bind_flags |= XDP_USE_NEED_WAKEUP;
>      }
> @@ -377,7 +384,11 @@ xsk_configure_socket(struct xsk_umem_info *umem, 
> uint32_t ifindex,
>      }
>
>      /* Make sure the built-in AF_XDP program is loaded. */
> +#ifdef HAVE_BPF_XDP_QUERY_ID
> +    ret = bpf_xdp_query_id(ifindex, cfg.xdp_flags, &prog_id);
> +#else
>      ret = bpf_get_link_xdp_id(ifindex, &prog_id, cfg.xdp_flags);
> +#endif
>      if (ret || !prog_id) {
>          if (ret) {
>              VLOG_ERR("Get XDP prog ID failed (%s)", ovs_strerror(errno));
> @@ -630,9 +641,9 @@ netdev_afxdp_set_config(struct netdev *netdev, const 
> struct smap *args,
>      }
>
>      need_wakeup = smap_get_bool(args, "use-need-wakeup", 
> NEED_WAKEUP_DEFAULT);
> -#ifndef HAVE_XDP_NEED_WAKEUP
> +#ifndef XDP_USE_NEED_WAKEUP
>      if (need_wakeup) {
> -        VLOG_WARN("XDP need_wakeup is not supported in libbpf.");
> +        VLOG_WARN("XDP need_wakeup is not supported in libbpf/libxdp.");
>          need_wakeup = false;
>      }
>  #endif
> @@ -742,7 +753,11 @@ xsk_remove_xdp_program(uint32_t ifindex, enum afxdp_mode 
> mode)
>      uint32_t ret, prog_id = 0;
>
>      /* Check whether XDP program is loaded. */
> +#ifdef HAVE_BPF_XDP_QUERY_ID
> +    ret = bpf_xdp_query_id(ifindex, flags, &prog_id);
> +#else
>      ret = bpf_get_link_xdp_id(ifindex, &prog_id, flags);
> +#endif
>      if (ret) {
>          VLOG_ERR("Failed to get XDP prog id (%s)", ovs_strerror(errno));
>          return;
> @@ -753,7 +768,14 @@ xsk_remove_xdp_program(uint32_t ifindex, enum afxdp_mode 
> mode)
>          return;
>      }
>
> -    bpf_set_link_xdp_fd(ifindex, -1, flags);
> +#ifdef HAVE_BPF_XDP_DETACH
> +    if (bpf_xdp_detach(ifindex, flags, NULL) != 0) {
> +#else
> +    if (bpf_set_link_xdp_fd(ifindex, -1, flags) != 0) {
> +#endif
> +        VLOG_ERR("Failed to detach XDP program (%s) at ifindex %d",
> +                 ovs_strerror(errno), ifindex);
> +    }
>  }
>
>  void
> diff --git a/rhel/openvswitch-fedora.spec.in b/rhel/openvswitch-fedora.spec.in
> index 4a3e6294b..6564d5252 100644
> --- a/rhel/openvswitch-fedora.spec.in
> +++ b/rhel/openvswitch-fedora.spec.in
> @@ -75,7 +75,7 @@ BuildRequires: dpdk-devel >= 22.11
>  Provides: %{name}-dpdk = %{version}-%{release}
>  %endif
>  %if %{with afxdp}
> -BuildRequires: libbpf-devel numactl-devel
> +BuildRequires: libxdp-devel libbpf-devel numactl-devel
>  %endif
>  BuildRequires: unbound unbound-devel
>
> -- 
> 2.38.1

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