Messages in this thread Patch in this message | | | Date | Fri, 24 Dec 2021 12:01:06 +0800 | From | Qiang Wang <> | Subject | Fix repeated legacy kprobes on same function |
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If repeated legacy kprobes on same function in one process, libbpf will register using the same probe name and got -EBUSY error. So append index to the probe name format to fix this problem.
And fix a bug in commit 46ed5fc33db9, which wrongly used the func_name instead of probe_name to register.
Fixes: 46ed5fc33db9 ("libbpf: Refactor and simplify legacy kprobe code") Co-developed-by: Chengming Zhou <zhouchengming@bytedance.com> Signed-off-by: Qiang Wang <wangqiang.wq.frank@bytedance.com> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
--- tools/lib/bpf/libbpf.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 7c74342bb668..7d1097958459 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -9634,7 +9634,8 @@ static int append_to_file(const char *file, const char *fmt, ...) static void gen_kprobe_legacy_event_name(char *buf, size_t buf_sz, const char *kfunc_name, size_t offset) { - snprintf(buf, buf_sz, "libbpf_%u_%s_0x%zx", getpid(), kfunc_name, offset); + static int index = 0; + snprintf(buf, buf_sz, "libbpf_%u_%s_0x%zx_%d", getpid(), kfunc_name, offset, index++); }
static int add_kprobe_event_legacy(const char *probe_name, bool retprobe, @@ -9735,7 +9736,7 @@ bpf_program__attach_kprobe_opts(const struct bpf_program *prog, gen_kprobe_legacy_event_name(probe_name, sizeof(probe_name), func_name, offset);
- legacy_probe = strdup(func_name); + legacy_probe = strdup(probe_name); if (!legacy_probe) return libbpf_err_ptr(-ENOMEM);
-- 2.20.1
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