From: Wang Hai wanghai38@huawei.com
[ Upstream commit 2620e92ae6ed83260eb46d214554cd308ee35d92 ]
Execute the following command and exit, then execute it again, the following error will be reported:
$ sudo ./samples/bpf/xdpsock -i ens4f2 -M ^C $ sudo ./samples/bpf/xdpsock -i ens4f2 -M libbpf: elf: skipping unrecognized data section(16) .eh_frame libbpf: elf: skipping relo section(17) .rel.eh_frame for section(16) .eh_frame libbpf: Kernel error message: XDP program already attached ERROR: link set xdp fd failed
Commit c9d27c9e8dc7 ("samples: bpf: Do not unload prog within xdpsock") removed the unloading prog code because of the presence of bpf_link. This is fine if XDP_SHARED_UMEM is disabled, but if it is enabled, unloading the prog is still needed.
Fixes: c9d27c9e8dc7 ("samples: bpf: Do not unload prog within xdpsock") Signed-off-by: Wang Hai wanghai38@huawei.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Magnus Karlsson magnus.karlsson@intel.com Cc: Maciej Fijalkowski maciej.fijalkowski@intel.com Link: https://lore.kernel.org/bpf/20210628091815.2373487-1-wanghai38@huawei.com Signed-off-by: Sasha Levin sashal@kernel.org --- samples/bpf/xdpsock_user.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+)
diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c index 53e300f860bb..33d0bdebbed8 100644 --- a/samples/bpf/xdpsock_user.c +++ b/samples/bpf/xdpsock_user.c @@ -96,6 +96,7 @@ static int opt_xsk_frame_size = XSK_UMEM__DEFAULT_FRAME_SIZE; static int opt_timeout = 1000; static bool opt_need_wakeup = true; static u32 opt_num_xsks = 1; +static u32 prog_id; static bool opt_busy_poll; static bool opt_reduced_cap;
@@ -461,6 +462,23 @@ static void *poller(void *arg) return NULL; }
+static void remove_xdp_program(void) +{ + u32 curr_prog_id = 0; + + if (bpf_get_link_xdp_id(opt_ifindex, &curr_prog_id, opt_xdp_flags)) { + printf("bpf_get_link_xdp_id failed\n"); + exit(EXIT_FAILURE); + } + + if (prog_id == curr_prog_id) + bpf_set_link_xdp_fd(opt_ifindex, -1, opt_xdp_flags); + else if (!curr_prog_id) + printf("couldn't find a prog id on a given interface\n"); + else + printf("program on interface changed, not removing\n"); +} + static void int_exit(int sig) { benchmark_done = true; @@ -471,6 +489,9 @@ static void __exit_with_error(int error, const char *file, const char *func, { fprintf(stderr, "%s:%s:%i: errno: %d/"%s"\n", file, func, line, error, strerror(error)); + + if (opt_num_xsks > 1) + remove_xdp_program(); exit(EXIT_FAILURE); }
@@ -490,6 +511,9 @@ static void xdpsock_cleanup(void) if (write(sock, &cmd, sizeof(int)) < 0) exit_with_error(errno); } + + if (opt_num_xsks > 1) + remove_xdp_program(); }
static void swap_mac_addresses(void *data) @@ -857,6 +881,10 @@ static struct xsk_socket_info *xsk_configure_socket(struct xsk_umem_info *umem, if (ret) exit_with_error(-ret);
+ ret = bpf_get_link_xdp_id(opt_ifindex, &prog_id, opt_xdp_flags); + if (ret) + exit_with_error(-ret); + xsk->app_stats.rx_empty_polls = 0; xsk->app_stats.fill_fail_polls = 0; xsk->app_stats.copy_tx_sendtos = 0;