Re: [RFC PATCH 0/6] tracing: wprobe: Add wprobe for watchpoint

Masami Hiramatsu
2025-09-10T01:11:33Z

> >> - trigger_data issue:
> >> it appears that the instance being removed is not the same as
> >> the one that was originally set.
> >
> > Did you mean it will free invalid struct event_trigger_data by
> > wprobe_trigger_free(), or hw_breakpoint instance?
> >
> > When trace_event_enable_disable(wprobe_data->file, 1, 1) at
> > wprobe_trigger_cmd_parse(), the trace_wprobe is enabled == call
> > enable_trace_wprobe(), which eventually call register_wide_hw_breakpoint()
> > with dummy address. IOW, the (wide)hw_breakpoint is allocated here.
> >
> > When the trigger is hit, modify_wide_hw_breakpoint_local() is called
> > for updating local target address on the same hw_breakpoint.
> > So latter instance should be the same.
> In wprobe_trigger_cmd_parse(), consider removing:
> echo '!set_wprobe:watch:dentry' >> events/fprobes/truncate/trigger
> The trigger_data passed to event_trigger_unregister() is freshly allocated.

Ah, thanks for pointing it out.
I confused to free newly allocated trigger_data instead of existing
one on the list.
Let me fix that.

Thank you,

--
Masami Hiramatsu (Google) <mhiramat@kernel.org>