在 2023/5/30 11:44, Ratheesh Kannoth 写道:
From: Jackie Liu <liu.yun@xxxxxxxxx>+ + if (!glob_match(sym_name, res->pattern)) + return 0; + + err = libbpf_ensure_mem((void **) &res->syms, &res->cap, + sizeof(const char *), res->cnt + 1); + if (err) + return err; + + name = strdup(sym_name); + if (!name) + return -errno; + + res->syms[res->cnt++] = name; + return 0; +} + +typedef int (*available_kprobe_cb_t)(const char *sym_name, void *ctx); + +static int +libbpf_available_kprobes_parse(available_kprobe_cb_t cb, void *ctx) +{ + char sym_name[256]; + FILE *f; + int ret, err = 0; + const char *available_path = tracefs_available_filter_functions();Dont we need to follow reverse x-mas tree ?+ + f = fopen(available_path, "r"); + if (!f) { + err = -errno; + pr_warn("failed to open %s, fallback to /proc/kallsyms.\n", + available_path); + return err; + } + + while (true) { + ret = fscanf(f, "%255s%*[^\n]\n", sym_name); + if (ret == EOF && feof(f)) + break;why fscanf() is not setting EOF. Why did you use feof() ?
The fscanf function returns EOF (End of File) when one of the following conditions is met:
End of file is reached: When fscanf reaches the end of the file being read, it returns EOF. This indicates that there are no more characters to read from the file.
Input error occurs: If fscanf encounters an error while reading input, such as a format mismatch or inability to read the expected data type, it returns EOF.
Stream error occurs: If an error occurs with the stream itself, such as an error in the underlying file system or I/O error, fscanf may return EOF.
-- Jackie Liu
+ if (ret != 1) { + pr_warn("failed to read available kprobe entry: %d\n", + ret); + err = -EINVAL; + break; + } + + err = cb(sym_name, ctx); + if (err) + break; + } + + fclose(f); + return err; +} + +static void kprobe_multi_resolve_free(struct kprobe_multi_resolve *res) +{ + while (res->syms && res->cnt) + free((char *)res->syms[--res->cnt]); + + free(res->syms); + free(res->addrs);it looks odd to do allocation in libbpf_xxx (libbpf_ensure_mem ) function and freeing in a static function.+ + /* reset to zero, when fallback */ + res->cap = 0; + res->cnt = 0; + res->syms = NULL; + res->addrs = NULL; +} + struct bpf_link * bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog, const char *pattern, @@ -10476,13 +10558,21 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog, return libbpf_err_ptr(-EINVAL); if (pattern) { - err = libbpf_kallsyms_parse(resolve_kprobe_multi_cb, &res); - if (err) - goto error; + err = libbpf_available_kprobes_parse(ftrace_resolve_kprobe_multi_cb, + &res); + if (err) { + /* fallback to kallsyms */ + kprobe_multi_resolve_free(&res); + err = libbpf_kallsyms_parse(kallsyms_resolve_kprobe_multi_cb, + &res); + if (err) + goto error; + } if (!res.cnt) { err = -ENOENT; goto error; } + syms = res.syms; addrs = res.addrs; cnt = res.cnt; } @@ -10511,12 +10601,12 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog, goto error; } link->fd = link_fd; - free(res.addrs); + kprobe_multi_resolve_free(&res); return link; error: free(link); - free(res.addrs); + kprobe_multi_resolve_free(&res); return libbpf_err_ptr(err); } -- 2.25.1
