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xdp-forward-queueing: Update outstanding bytes #497

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8fae438
xdp-forward: add state update on packet egress
luisjira Mar 25, 2025
4847583
xdp-forward: attach return function to tracepoint
luisjira Mar 25, 2025
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57 changes: 57 additions & 0 deletions xdp-forward/xdp-forward.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,8 @@
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>

#include <bpf/libbpf.h>
#include <xdp/libxdp.h>
Expand Down Expand Up @@ -140,7 +142,10 @@ static int do_load(const void *cfg, __unused const char *pin_root_path)
{
struct xdp_program *xdp_prog = NULL, *init_prog = NULL;
DECLARE_LIBBPF_OPTS(xdp_program_opts, opts);
struct bpf_program *return_prog = NULL;
const struct load_opts *opt = cfg;
struct bpf_link *link = NULL;
char pin_link_path[PATH_MAX];
struct xdp_forward *skel;
int ret = EXIT_FAILURE;
struct iface *iface;
Expand Down Expand Up @@ -217,6 +222,34 @@ static int do_load(const void *cfg, __unused const char *pin_root_path)
pr_info("Loaded on interface %s\n", iface->ifname);
}

/* Attach xdp_check_return to xdp_frame_return tracepoint and
* pin the link to pin_root_path/xdp_check_return.
*/

return_prog = bpf_object__find_program_by_name(skel->obj,"xdp_check_return");
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@tohojo tohojo Mar 31, 2025

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The program is available in the skeleton as skel->progs.xdp_check_return - no need to use bpf_object__find_program_by_name()

if (!return_prog) {
pr_warn("Failed to find xdp_check_return program\n");
goto end_detach;
}

link = bpf_program__attach_raw_tracepoint(return_prog, "xdp_frame_return");
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@tohojo tohojo Mar 31, 2025

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It should be possible to just call bpf_program__attach(), since the target is specified in the section definition in the BPF source file.

if (libbpf_get_error((const void *) link)) {
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@tohojo tohojo Mar 31, 2025

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It should be possible to just pass the pointers to libbpf_get_error() without the cast...

pr_warn("Couldn't attach to xdp_frame_return: %s\n",
strerror(libbpf_get_error((const void *) link)));
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@tohojo tohojo Mar 31, 2025

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...same here

goto end_detach;
}
skel->links.xdp_check_return = link;

snprintf(pin_link_path, sizeof(pin_link_path), "%s/%s", pin_root_path,
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@tohojo tohojo Mar 31, 2025

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This should use the try_snprintf() function (from lib/util), and check the return code. We should probably also disambiguate the pin path right now, with this path bad things will happen if multiple instances of xdp-forward are loaded at the same time.

"xdp_check_return");
ret = bpf_link__pin(link, pin_link_path);
if (ret) {
pr_warn("Failed to pin link: %s\n",
strerror(errno));
goto end_detach;
}
pr_info("Pinned xdp_check_return to %s\n", pin_link_path);
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@tohojo tohojo Mar 31, 2025

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This should probably be pr_debug()


end_destroy:
xdp_forward__destroy(skel);
end:
Expand All @@ -225,6 +258,10 @@ static int do_load(const void *cfg, __unused const char *pin_root_path)
end_detach:
for (iface = opt->ifaces; iface; iface = iface->next)
xdp_program__detach(xdp_prog, iface->ifindex, opt->xdp_mode, 0);

bpf_link__unpin(link);
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@tohojo tohojo Mar 31, 2025

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bpf_link__unpin() will crash if link is NULL

bpf_link__destroy(link);

goto end_destroy;
}

Expand All @@ -246,6 +283,8 @@ struct prog_option unload_options[] = {
static int do_unload(const void *cfg, __unused const char *pin_root_path)
{
const struct unload_opts *opt = cfg;
struct bpf_link *link = NULL;
char pin_link_path[PATH_MAX];
int ret = EXIT_SUCCESS;
struct iface *iface;

Expand All @@ -258,6 +297,24 @@ static int do_unload(const void *cfg, __unused const char *pin_root_path)
pr_info("Unloaded from interface %s\n", iface->ifname);
}

snprintf(pin_link_path, sizeof(pin_link_path), "%s/%s", pin_root_path,
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@tohojo tohojo Mar 31, 2025

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See above wrt using try_snprintf()

"xdp_check_return");

link = bpf_link__open(pin_link_path);
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@tohojo tohojo Mar 31, 2025

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Instead of going through this open/unpin/destroy dance, just unlink the pin file?

ret = bpf_link__unpin(link);
if(ret){
pr_warn("Couldn't unpin link\n");
} else {
pr_info("Unpinned link from %s\n", pin_link_path);
}

ret = bpf_link__destroy(link);
if(ret){
pr_warn("Couldn't destroy link\n");
} else {
pr_info("Destroyed link\n");
}

return ret;
}

Expand Down
1 change: 1 addition & 0 deletions xdp-forward/xdp_forward.bpf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -94,6 +94,7 @@ static int xdp_timer_cb(struct bpf_map *map, __u64 *key, struct bpf_timer *timer

bpf_printk("xdp_timer_cb: Sending to ifindex %d\n", tgt_ifindex);
xdp_packet_send(pkt, tgt_ifindex, 0);
state->outstanding_bytes += pkt->len;
}

xdp_packet_flush();
Expand Down