mirror of
https://github.com/xdp-project/bpf-examples.git
synced 2024-05-06 15:54:53 +00:00
25acd99b58
Minimal example to show that the close() operation on a bpf_link can hang indefinitely if the kernel is loaded (for example by traffic on an interface with an XDP program loaded). Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
66 lines
2.0 KiB
C
66 lines
2.0 KiB
C
#include <string.h>
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#include <errno.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <signal.h>
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#include <time.h>
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#include <net/if.h>
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#include <linux/if_link.h>
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#include <bpf/libbpf.h>
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#include <bpf/bpf.h>
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static inline int64_t timespec_ns(struct timespec* a)
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{
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return ((int64_t) a->tv_sec * 1000000000) + a->tv_nsec;
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}
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int main()
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{
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struct bpf_object *obj_target, *obj_prog;
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struct bpf_program *target, *prog;
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struct timespec start_time, end_time;
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int err = EXIT_FAILURE, lfd;
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obj_target = bpf_object__open_file("xdp-pass.o", NULL);
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obj_prog = bpf_object__open_file("xdp-pass.o", NULL);
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if (libbpf_get_error(obj_target) || libbpf_get_error(obj_prog))
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goto out;
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if (bpf_object__load(obj_target))
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goto out;
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target = bpf_object__find_program_by_title(obj_target, "xdp/pass");
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prog = bpf_object__find_program_by_title(obj_prog, "xdp/pass");
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if (!target || !prog)
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goto out;
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bpf_program__set_type(prog, BPF_PROG_TYPE_EXT);
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bpf_program__set_expected_attach_type(prog, 0);
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if (bpf_program__set_attach_target(prog, bpf_program__fd(target), "xdp_pass"))
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goto out;
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if (bpf_object__load(obj_prog))
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goto out;
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lfd = bpf_raw_tracepoint_open(NULL, bpf_program__fd(prog));
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if (lfd < 0)
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goto out;
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printf("\nClosing link fd (%d) - this should hang if the system is loaded...\n", lfd);
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clock_gettime(CLOCK_REALTIME, &start_time);
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close(lfd);
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clock_gettime(CLOCK_REALTIME, &end_time);
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printf("Link fd closed in %lu ms!\n", (timespec_ns(&end_time) - timespec_ns(&start_time)) / 1000000);
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err = 0;
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out:
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if (obj_target && !libbpf_get_error(obj_target))
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bpf_object__close(obj_target);
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if (obj_prog && !libbpf_get_error(obj_prog))
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bpf_object__close(obj_prog);
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printf(err ? "An error occurred!\n" : "Exited successfully\n");
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return err;
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}
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