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samples/bpf: xdp_redirect load XDP dummy prog on TX device

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For supporting XDP_REDIRECT, a device driver must (obviously)
implement the "TX" function ndo_xdp_xmit().  An additional requirement
is you cannot TX out a device, unless it also have a xdp bpf program
attached. This dependency is caused by the driver code need to setup
XDP resources before it can ndo_xdp_xmit.

Update bpf samples xdp_redirect and xdp_redirect_map to automatically
attach a dummy XDP program to the configured ifindex_out device.  Use
the XDP flag XDP_FLAGS_UPDATE_IF_NOEXIST on the dummy load, to avoid
overriding an existing XDP prog on the device.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jesper Dangaard Brouer 2017-08-29 16:38:06 +02:00 committed by David S. Miller
parent 59a3089675
commit 306da4e685
4 changed files with 50 additions and 15 deletions
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11
samples/bpf/xdp_redirect_kern.c
View File

@ -26,6 +26,9 @@ struct bpf_map_def SEC("maps") tx_port = {
.max_entries = 1,
};
/* Count RX packets, as XDP bpf_prog doesn't get direct TX-success
* feedback. Redirect TX errors can be caught via a tracepoint.
*/
struct bpf_map_def SEC("maps") rxcnt = {
.type = BPF_MAP_TYPE_PERCPU_ARRAY,
.key_size = sizeof(u32),
@ -33,7 +36,6 @@ struct bpf_map_def SEC("maps") rxcnt = {
.max_entries = 1,
};
static void swap_src_dst_mac(void *data)
{
unsigned short *p = data;
@ -78,4 +80,11 @@ int xdp_redirect_prog(struct xdp_md *ctx)
return bpf_redirect(*ifindex, 0);
}
/* Redirect require an XDP bpf_prog loaded on the TX device */
SEC("xdp_redirect_dummy")
int xdp_redirect_dummy(struct xdp_md *ctx)
{
return XDP_PASS;
}
char _license[] SEC("license") = "GPL";

11
samples/bpf/xdp_redirect_map_kern.c
View File

@ -26,6 +26,9 @@ struct bpf_map_def SEC("maps") tx_port = {
.max_entries = 100,
};
/* Count RX packets, as XDP bpf_prog doesn't get direct TX-success
* feedback. Redirect TX errors can be caught via a tracepoint.
*/
struct bpf_map_def SEC("maps") rxcnt = {
.type = BPF_MAP_TYPE_PERCPU_ARRAY,
.key_size = sizeof(u32),
@ -33,7 +36,6 @@ struct bpf_map_def SEC("maps") rxcnt = {
.max_entries = 1,
};
static void swap_src_dst_mac(void *data)
{
unsigned short *p = data;
@ -80,4 +82,11 @@ int xdp_redirect_map_prog(struct xdp_md *ctx)
return bpf_redirect_map(&tx_port, vport, 0);
}
/* Redirect require an XDP bpf_prog loaded on the TX device */
SEC("xdp_redirect_dummy")
int xdp_redirect_dummy(struct xdp_md *ctx)
{
return XDP_PASS;
}
char _license[] SEC("license") = "GPL";

22
samples/bpf/xdp_redirect_map_user.c
View File

@ -16,6 +16,7 @@
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <unistd.h>
#include <libgen.h>
@ -26,17 +27,18 @@
static int ifindex_in;
static int ifindex_out;
static bool ifindex_out_xdp_dummy_attached = true;
static __u32 xdp_flags;
static void int_exit(int sig)
{
set_link_xdp_fd(ifindex_in, -1, xdp_flags);
if (ifindex_out_xdp_dummy_attached)
set_link_xdp_fd(ifindex_out, -1, xdp_flags);
exit(0);
}
/* simple per-protocol drop counter
*/
static void poll_stats(int interval, int ifindex)
{
unsigned int nr_cpus = bpf_num_possible_cpus();
@ -70,7 +72,6 @@ static void usage(const char *prog)
prog);
}
int main(int argc, char **argv)
{
const char *optstr = "SN";
@ -112,14 +113,21 @@ int main(int argc, char **argv)
return 1;
}
signal(SIGINT, int_exit);
signal(SIGTERM, int_exit);
if (set_link_xdp_fd(ifindex_in, prog_fd[0], xdp_flags) < 0) {
printf("link set xdp fd failed\n");
printf("ERROR: link set xdp fd failed on %d\n", ifindex_in);
return 1;
}
/* Loading dummy XDP prog on out-device */
if (set_link_xdp_fd(ifindex_out, prog_fd[1],
(xdp_flags | XDP_FLAGS_UPDATE_IF_NOEXIST)) < 0) {
printf("WARN: link set xdp fd failed on %d\n", ifindex_out);
ifindex_out_xdp_dummy_attached = false;
}
signal(SIGINT, int_exit);
signal(SIGTERM, int_exit);
printf("map[0] (vports) = %i, map[1] (map) = %i, map[2] (count) = %i\n",
map_fd[0], map_fd[1], map_fd[2]);

21
samples/bpf/xdp_redirect_user.c
View File

@ -16,6 +16,7 @@
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <unistd.h>
#include <libgen.h>
@ -26,17 +27,18 @@
static int ifindex_in;
static int ifindex_out;
static bool ifindex_out_xdp_dummy_attached = true;
static __u32 xdp_flags;
static void int_exit(int sig)
{
set_link_xdp_fd(ifindex_in, -1, xdp_flags);
if (ifindex_out_xdp_dummy_attached)
set_link_xdp_fd(ifindex_out, -1, xdp_flags);
exit(0);
}
/* simple per-protocol drop counter
*/
static void poll_stats(int interval, int ifindex)
{
unsigned int nr_cpus = bpf_num_possible_cpus();
@ -112,14 +114,21 @@ int main(int argc, char **argv)
return 1;
}
signal(SIGINT, int_exit);
signal(SIGTERM, int_exit);
if (set_link_xdp_fd(ifindex_in, prog_fd[0], xdp_flags) < 0) {
printf("link set xdp fd failed\n");
printf("ERROR: link set xdp fd failed on %d\n", ifindex_in);
return 1;
}
/* Loading dummy XDP prog on out-device */
if (set_link_xdp_fd(ifindex_out, prog_fd[1],
(xdp_flags | XDP_FLAGS_UPDATE_IF_NOEXIST)) < 0) {
printf("WARN: link set xdp fd failed on %d\n", ifindex_out);
ifindex_out_xdp_dummy_attached = false;
}
signal(SIGINT, int_exit);
signal(SIGTERM, int_exit);
/* bpf redirect port */
ret = bpf_map_update_elem(map_fd[0], &key, &ifindex_out, 0);
if (ret) {