Em Mon, Mar 11, 2019 at 10:30:43PM -0700, Song Liu escreveu:
> +static int write_bpf_prog_info(struct feat_fd *ff,
> + struct perf_evlist *evlist __maybe_unused)
> +{
> + struct perf_env *env = &ff->ph->env;
> + struct rb_root *root;
> + struct rb_node *next;
> + int ret;
> +
> + down_read(&env->bpf_progs.lock);
> +
> + ret = do_write(ff, &env->bpf_progs.infos_cnt,
> + sizeof(env->bpf_progs.infos_cnt));
> + if (ret < 0)
> + goto out;
> +
> + root = &env->bpf_progs.infos;
> + next = rb_first(root);
> + while (next) {
> + struct bpf_prog_info_node *node;
> + size_t len;
> +
> + node = rb_entry(next, struct bpf_prog_info_node, rb_node);
> + next = rb_next(&node->rb_node);
> + len = sizeof(struct bpf_prog_info_linear) +
> + node->info_linear->data_len;
> +
> + /* before writing to file, translate address to offset */
> + bpf_program__bpil_addr_to_offs(node->info_linear);
> + ret = do_write(ff, node->info_linear, len);
> + /*
> + * translate back to address even when do_write() fails,
> + * so that this function never changes the data.
> + */
> + bpf_program__bpil_offs_to_addr(node->info_linear);
> + if (ret < 0)
> + goto out;
> + }
> +out:
> + up_read(&env->bpf_progs.lock);
> + return ret;
> +}
The above uses libbpf functions unconditionally, leading to build
failures when NO_LIBBPF=1 is passed or libbpf somehow is not available
or can't be built.
So I added this:
+#else // HAVE_LIBBPF_SUPPORT
+static int write_bpf_prog_info(struct feat_fd *ff __maybe_unused,
+ struct perf_evlist *evlist __maybe_unused)
+{
+ return 0;
+}
+#endif // HAVE_LIBBPF_SUPPORT
And added this committer notes:
Committer notes:
We can't use the libbpf unconditionally, as the build may have been with
NO_LIBBPF, when we end up with linking errors, so provide a dummy
write_bpf_prog_info() wrapped by HAVE_LIBBPF_SUPPORT for that case.
Reading and printing are not affected by this, so can continue as is.
