Re: [PATCH 2/2] libbpf: Support repeated legacy kprobes on same function

[Hengqi Chen <hengqi.chen@gmail.com>]

On 2021/12/25 4:32 PM, Qiang Wang wrote:
> 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.
> 
> 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 | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index b7d6c951fa09..0c41a45ffd54 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -9634,7 +9634,9 @@ 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;

Add empty line after variable declaration.

> +	snprintf(buf, buf_sz, "libbpf_%u_%s_0x%zx_%d", getpid(), kfunc_name, offset

Missing a comma after offset.

> +		 __sync_fetch_and_add(&index, 1));
>  }
>  
>  static int add_kprobe_event_legacy(const char *probe_name, bool retprobe,