Re: [PATCH] tracing/uprobe: Fix double perf_event linking on multiprobe uprobe

Peter Zijlstra
2020-01-20T12:40:54Z

On Fri, Jan 10, 2020 at 10:45:39AM +0900, Masami Hiramatsu wrote:

> diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> index 4ee703728aec..03e4e180058d 100644
> --- a/kernel/trace/trace_probe.h
> +++ b/kernel/trace/trace_probe.h
> @@ -230,6 +230,7 @@ struct trace_probe_event {
> struct trace_event_call call;
> struct list_head files;
> struct list_head probes;
> + char data[0];
> };

Would it make sense to make the above:

struct trace_uprobe_filter filter[0];

instead? That would ensure that alignment is respected. While I think
the current code works by accident.

> @@ -264,6 +263,14 @@ process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
> }
> NOKPROBE_SYMBOL(process_fetch_insn)
>
> +static struct trace_uprobe_filter *
> +trace_uprobe_get_filter(struct trace_uprobe *tu)
> +{
> + struct trace_probe_event *event = tu->tp.event;
> +
> + return (struct trace_uprobe_filter *)&event->data[0];
> +}