From: Qiang Wang <wangqiang.wq.frank@bytedance.com>
To: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
kafai@fb.com, songliubraving@fb.com, yhs@fb.com,
john.fastabend@gmail.com, kpsingh@kernel.org,
zhouchengming@bytedance.com, songmuchun@bytedance.com,
duanxiongchun@bytedance.com, shekairui@bytedance.com
Cc: netdev@vger.kernel.org, bpf@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Fix repeated legacy kprobes on same function
Date: Fri, 24 Dec 2021 12:01:06 +0800 [thread overview]
Message-ID: <c84094d2-75c1-a50d-ea9e-9dded5f01fb9@bytedance.com> (raw)
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
next reply other threads:[~2021-12-24 4:01 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-24 4:01 Qiang Wang [this message]
2021-12-24 6:57 ` Fix repeated legacy kprobes on same function Andrii Nakryiko
2021-12-24 7:38 ` [External] " Chengming Zhou
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