Zhengchao Shao <[email protected]> writes:
> Before detach the prog, we should check detach prog exist or not.
>
> Signed-off-by: Zhengchao Shao <[email protected]>
> ---
> samples/bpf/xdp_fwd_user.c | 59 ++++++++++++++++++++++++++++++++------
> 1 file changed, 50 insertions(+), 9 deletions(-)
>
> diff --git a/samples/bpf/xdp_fwd_user.c b/samples/bpf/xdp_fwd_user.c
> index 1828487bae9a..03a50f64e99a 100644
> --- a/samples/bpf/xdp_fwd_user.c
> +++ b/samples/bpf/xdp_fwd_user.c
> @@ -47,17 +47,58 @@ static int do_attach(int idx, int prog_fd, int map_fd, const char *name)
> return err;
> }
>
> -static int do_detach(int idx, const char *name)
> +static int do_detach(int ifindex, const char *ifname, const char *app_name)
> {
> - int err;
> + LIBBPF_OPTS(bpf_xdp_attach_opts, opts);
> + struct bpf_prog_info prog_info = {};
> + char prog_name[BPF_OBJ_NAME_LEN];
> + __u32 info_len, curr_prog_id;
> + int prog_fd;
> + int err = 1;
> +
> + if (bpf_xdp_query_id(ifindex, xdp_flags, &curr_prog_id)) {
> + printf("ERROR: bpf_xdp_query_id failed (%s)\n",
> + strerror(errno));
> + return err;
> + }
> +
> + if (!curr_prog_id) {
> + printf("ERROR: flags(0x%x) xdp prog is not attached to %s\n",
> + xdp_flags, ifname);
> + return err;
> + }
>
> - err = bpf_xdp_detach(idx, xdp_flags, NULL);
> - if (err < 0)
> - printf("ERROR: failed to detach program from %s\n", name);
> + info_len = sizeof(prog_info);
> + prog_fd = bpf_prog_get_fd_by_id(curr_prog_id);
This fd is never closed again; you'll need to replace the 'return err'
statement below with a 'goto err' and add a label at the end that closes
the fd before returning - see comments below.
> + if (prog_fd < 0) {
> + printf("ERROR: bpf_prog_get_fd_by_id failed (%s)\n",
> + strerror(errno));
> + return err;
err is not actually set here; you could either 'return prog_fd' or
'return -errno'.
> + }
> +
> + err = bpf_obj_get_info_by_fd(prog_fd, &prog_info, &info_len);
> + if (err) {
> + printf("ERROR: bpf_obj_get_info_by_fd failed (%s)\n",
> + strerror(errno));
> + return err;
make this 'goto err'...
> + }
> + snprintf(prog_name, sizeof(prog_name), "%s_prog", app_name);
> + prog_name[BPF_OBJ_NAME_LEN - 1] = '\0';
> +
> + if (strcmp(prog_info.name, prog_name)) {
> + printf("ERROR: %s isn't attached to %s\n", app_name, ifname);
> + err = 1;
> + } else {
> + opts.old_prog_fd = prog_fd;
> + err = bpf_xdp_detach(ifindex, xdp_flags, &opts);
> + if (err < 0)
> + printf("ERROR: failed to detach program from %s (%s)\n",
> + ifname, strerror(errno));
> + /* TODO: Remember to cleanup map, when adding use of shared map
> + * bpf_map_delete_elem((map_fd, &idx);
> + */
> + }
>
> - /* TODO: Remember to cleanup map, when adding use of shared map
> - * bpf_map_delete_elem((map_fd, &idx);
> - */
...and add something like:
err:
close(prog_fd);
> return err;
> }
>
> @@ -169,7 +210,7 @@ int main(int argc, char **argv)
> return 1;
> }
> if (!attach) {
> - err = do_detach(idx, argv[i]);
> + err = do_detach(idx, argv[i], prog_name);
> if (err)
> ret = err;
> } else {
> --
> 2.17.1