Re: [PATCH v2] tracing/uprobe: Add missing PID filter for uretprobe

[Oleg Nesterov <oleg@redhat.com>]

Sorry for another reply, I just noticed I missed one part of your email...

On 08/27, Jiri Olsa wrote:
>
>    ->     uretprobe-hit
>             handle_swbp
>               uprobe_handle_trampoline
>                 handle_uretprobe_chain
>                 {
>
>                   for_each_uprobe_consumer {
>
>                     // consumer for task 1019
>                     uretprobe_dispatcher
>                       uretprobe_perf_func
>                         -> runs bpf program
>
>                     // consumer for task 1018
>                     uretprobe_dispatcher
>                       uretprobe_perf_func
>                         -> runs bpf program
>
>                   }
>                 }
>
> and I think the same will happen for perf record in this case where instead of
> running the program we will execute perf_tp_event

Hmm. Really? In this case these 2 different consumers will have the different
trace_event_call's, so

	// consumer for task 1019
	uretprobe_dispatcher
	  uretprobe_perf_func
	    __uprobe_perf_func
	      perf_tp_event

won't store the event because this_cpu_ptr(call->perf_events) should be
hlist_empty() on this CPU, the perf_event for task 1019 wasn't scheduled in
on this CPU...

No?

Ok, looks like I'm totally confused ;)

Oleg.